Questions on: Arborvitae
Ron Smith, Horticulturist, NDSU Extension Service
Q: I have what I believe is nigra arborvitae as a natural fence around my home. A neighbor told me that it's too bad that arborvitae dies after 20 or so years. Is this true? (Bellingham, Wash.)
A: That might be wishful thinking on your neighbor's part, so keep an eye on him! There are many arborvitaes that are more than 50 years old in my old neighborhood where I grew up. I can tell you the plants received no special treatment in Buffalo, N.Y., which is famous for its winters and other irrational, unpredictable weather.
Q: Two years ago I planted 25 arborvitae trees. This year they are starting to turn brown. They are greener toward the outside of the tree. I used Miracle-Gro arborvitae tree stakes about two weeks ago. I was hoping to see improvement, but nothing so far. Any ideas? Everything else in my yard is doing well. The trees are getting about two hours of soaker hose watering every other day. They are shaded in the morning and have full light for most of the day. (Long Island, N.Y.)
A: You are watering too much, so back off on that. Don't expect to see any significant results from the fertilizer spikes. You may see some improvement through the summer after you allow the trees to dry down. A good soaking no more than once a week should be more than enough.
Q: I live in the northern part of Ontario. We purchased 70 emerald green arborvitaes and planted them this past weekend. Because of where we live, I would like to know if I should wrap them with burlap this winter. Also, should I use an anti-desiccant spray for foliage so they remain green? I am using the arborvitae as a hedge for privacy. Our winters here can go to minus 40 in the winter. (Timmins, Ontario)
A: Wrap them in burlap, but avoid using any anti-desiccants. We have had mixed results with the material. With a planting this large, I would hate to see you lose all of them because you used an anti-desiccant. Be sure they go into winter well hydrated. Don't fertilize because this will cause soft, lush growth that looks beautiful, but is vulnerable to winter burn. After about three winters, you should not need to continue with the wrapping. Your winters are no worse than ours here in North Dakota!
Q: I have had it with my arborvitae. For the past three years, I have replaced the three I had next to the west side of my house. They grew well during the summer. In winter, I sprayed them with Wiltpruf and covered them with burlap, but they turned brown in the spring. Could you recommend something hardier that can handle the afternoon heat and a fair amount of water from my sprinkler system? Maybe I just can't grow trees! (e-mail reference)
A: Not too many evergreens can take the direct impact of lawn sprinklers. Why not try a deciduous evergreen? The Larix decidua is hardy for this area. It resembles a spruce when in needle, provides fresh, new growth every spring and is not subject to winter damage due to dropping of the needles in the fall. To check out the characteristics of this species, go to http://www.mobot.org/gardeninghelp/plantfinder/Plant.asp?Code=A163.
Q: We are installing an above-ground pool in early May. We have a privacy fence that will be approximately 8 feet away from the pool. It provides some privacy, but not enough because the house behind us is quite tall. I was interested in possibly planting some arborvitaes against the fence to increase privacy. My neighbor has these trees against our fence. They have done well for years. What is your opinion about the idea? (Rochester, N.Y.)
A: Sounds like a good plan. Go for it!
Q: After looking at a number of nurseries, I've found none that have techny in stock. They all say that they can get them, but I'd prefer to see what I'm getting before I buy. It seems that there are lots of emeralds available. One nursery had a bunch of them available at what looked to be a reasonable price. Do you have any problem with emeralds? Emeralds have less spread, so I probably would have to buy more of them. (Pittsburgh, Pa.)
A: Go for the emeralds because there is no point in ordering something else when these beauties are available. Send some to me! Ask when they were dug from the nursery because I'm curious.
Q: I am not sure what type of arborvitae would give me the results I'm looking for. I have a retaining wall behind my property. The wall needs to be repaired in several sections. Above the retaining wall there are a number of old evergreen trees, which we plan to have removed. We would like to replace these trees with nice looking border shrubs, so we are considering some type of arborvitae. Some people have suggested green giant, but I think these would get too big. Your column mentions emerald, techny and Brandon. Since the wall slopes downward north to south into the primary privacy impact zone, we would like to have taller shrubs on the lower end than on the higher end. I think we would need a full-grown height of 12 feet or more at the lower end. The ground also slopes from the neighbor's driveway toward the wall, so those shrubs also would be planted on a grade. Could you suggest a variety that would be appropriate for this project and the sizes of shrubs you would plant? Although this is a suburban area, deer are a concern. Since I am investing $4,000 in fixing the retaining wall and $2,000 to remove the trees, I'd like my investment in arborvitae to be a sound one. (Pittsburgh, Pa.)
A: In another life, I used to live in the Pittsburgh area near the airport and had a view of the beginning of the Ohio River. I would advise purchasing the techny cultivar of arborvitae and a smaller-sized arborvitae as well. Of greater issue to me are the problem trees you have. As for the amount of dollars you are going to spend, be sure to check the pedigree of the people you are going to hire to do the work. They should be able to provide you with good references, which I advise checking on. Be sure they are adequately insured for any property damage that may occur.
Q: We have arborvitae screening our entire backyard. I don't think the prior owners watered very well. However, the arborvitae that borders another neighbor's yard is doing well, presumably because they were able to utilize water from his watered lawn. On another side, though, the neighbor installed a gravel strip several years ago along his side of the fence. These arborvitae have become thin on the lower half. The top 3 feet are thick and bushy (maybe because that is relatively new growth and we have been doing a good job of watering). Is there any way, even with meticulous pruning, that the lower half of the sparse arborvitae can be made to bush out or at least to branch out to the left and right sides (which would provide more screening) versus branches/foliage growing right toward the house (which doesn’t provide much screening)? If so, any details on how exactly to prune would be much appreciated! (e-mail reference)
A: You are an ambitious man, but save it for something that will reward your efforts! Unless these trees get generous amounts of sunlight, water and nutrients, chances are they will remain wimpy, thin plants in those respective areas. Sorry! You might be better off digging them out, reworking the soil to support better growth and planting some fresh arborvitaes.
Q: Landscapers planted 6-feet-tall emerald arborvitae. The plants are spaced at 6-foot intervals. I did it to screen the view of my neighbor's house. Did they plant the trees too far apart? Should I plant something between the arborvitae? Are there any plants I should avoid planting near the arborvitae that would hurt their growth? I was thinking of planting grasses near or between them to complete the screen. I live in Missouri. Thanks for any help you can provide. (e-mail reference)
A: No need to plant anything in between because they eventually will spread to form a solid screen. If the distance is too much for you to bear, then plant some mug pines between them. However, you probably will end up having to cut them out in six or so years. They don't like being shaded too much, so don't plant any deciduous trees that will form a canopy over them.
Q: I live in Boston. I would like a wall of some form (arborvitae) that is tall and thick. The wall would be 100 feet long. I also would like to find trees that would get to 8 feet in two years, with no cropping of the tops. The area gets above average to average sunlight. The soil is excellent and the moisture and drainage is very good. I would like the space between the trees to fill in within two years to a maximum width of 4 feet. If the width is going be greater, I'd like to be able to trim the trees without losing coverage. The trees will be planted against a chain link fence. What is your suggested arborvitae, distance between plantings and distance from the fence? What type of ivy or plant would you recommend planting along the fence to act as filler on the lower side. (e-mail reference)
A: You need to find what arborvitae cultivars are available on the local market. Emerald, nigra, pyramidalis or techny (aka Mission) would all do the job for you. Techny is the most popular. I would suggest planting 4 feet from the fence and the same distance between plants because they will spread 4 feet or more and reach at least 15 feet in height. As to the vine, the vines I know of would become a problem because of rampant growth. You might want to check with your Extension Service to see if a horticulturist could make some "safe" suggestions.
Q: Can you suggest a pyramidal arborvitae variety that will be useful for a hedgerow in an area that sees light to medium shade from large oaks nearby? (e-mail reference)
A: No, I can't because I have no idea what part of the country you are talking about. It also is very unlikely that the shade from the oaks will remain light to medium, which will cause the arborvitae to decline and possibly die. If where you live will support them, Canadian hemlocks may be the better choice.
Q: Last fall, one of my arborvitae trees was infested with cabbage worms. Before I could get some Sevin spray on it, the entire tree turned brown. I decided to leave it for the winter before pulling it out and throwing it away. Is it too late? What causes cabbage worms? We have lived here seven years. The worst insect problem I have had was Japanese beetle, which the Sevin spray took care of. I don't want to lose any more of my evergreens to this pest. Any help you can give me will be much appreciated. (e-mail reference)
A: They say there is a first time for everything and this is one of them. Who diagnosed the insect larvae as cabbage worms? I am not an expert entomologist, but in the decades of my long life, I never have heard of or seen this pest anywhere near arborvitae plants. Are you sure the insects aren’t bagworms? This is a common pest on arborvitae and easily controlled with systemic insecticides. It also could be sawfly larvae, which are voracious feeders on many species of evergreens. Sawfly larvae usually concentrate in masses around the tender growth at the ends of the branches. This problem also can be controlled with systemic insecticides. These and many insects are controlled with systemics that have contact and systemic activity. Orthene is used a lot for this sort of problem.
A: A major part of the nursery stock sold in America comes from Pacific Northwest nurseries and settles in quite well in varying landscapes. Generally, these nurseries are wholesale nurseries. They require that the purchaser be a licensed nursery stock handler and that the plants be purchased in larger quantities to obtain the prices that look tempting to you. Any nursery that would retail from Oregon or Washington to a homeowner in Chicago would be open to suspicion to me. I would advise you to go for smaller stock plants because they will establish very quickly and save you money as well. Smaller plants equal less loss of roots during transplanting and quicker establishment and growth. Insist on a guarantee of the stock the landscaper installs. Ask for a couple of references for the Brandon arborvitae that he has planted in your area. If, for any reason, you doubt the integrity of this landscaper, don't do business with him. There are plenty of reputable firms out there that you can do business with. The biggest problem with importing from out of state is that you end up accepting what is shipped to you - with little control over the handling of the stock. In transport, they could be subjected to wind or heat desiccation that would not be apparent at the time of planting, but resulting in the gradual death of the plants in several months or years.
A: The deer will thank you for planting arborvitae! I would suggest contacting the local Department of Natural Resources for suggestions and possible contributions of deer- resistant plant material for you to use.
I read and enjoy your answers to arborvitae questions in Hortiscope. I
planted two rows of emerald greens 12 years ago. They are doing fairly
well. The plants are about 15 feet tall. I am thinking of trimming the
tops so they will be more stable during winter snows. How many feet can
I safely take off the top? Will the arborvitae grow back after
trimming? (e-mail reference)
A: From a rule of thumb standpoint, cut back about 2
feet off the top.
Cut near to a lateral branch. Yes, they will regrow after pruning. I
would suggest doing the pruning in early spring before new growth
begins. You could avoid pruning by tying a cotton cloth about 2 to 3
feet from the top to keep the snow from splaying the branches apart.
Q: You mention using burlap to protect arborvitae from heavy snow. Can I leave it on for the winter or do I just put it on when heavy snow is in the forecast? (e-mail reference)
A: Most people find it easier to leave it on through the worst part of the winter. The middle of the winter, as harsh as it may get, often is not the hardest on trees. It is the spring weather. The ground freezes in late fall or early winter and still is frozen in March. We might have air temperatures and sunshine that gets the evergreen plant tissue physiologically active by transpiring moisture through stomata openings. With the roots in frozen soil, it is not possible to get the lost moisture moved to the foliage, which causes desiccation to take place or possibly foliage death. Typically, this occurs on the south and west exposures, so make sure those two sides are protected with burlap. The burlap doesn't protect the arborvitae from heavy snows. If a heavy snowfall is in the forecast, I suggest getting oak stakes and tying the stakes on the main stems using twist ties or cotton twine. This will keep them from bending out of shape or possibly breaking.
Q: I was reading your information on arborvitaes and noticed many people fertilize with Miracid. You mentioned fertilizing once in the spring with Miracle-Gro. The label on the arborvitaes I purchased says they prefer slightly alkaline soil. I'm wondering now whether to fertilize with Miracle-Gro or Miracid? (e-mail reference)
A: Sterns, the company that makes these products, has solved the problem by no longer making Miracid. Arborvitaes are widely used across a wide spectrum of landscape situations and soil types because of how easily they adapt to conditions. I have seen them thrive alongside azaleas and rhododendrons in the acid soils of the eastern U.S. I also have seen arborvitaes doing well in the alkaline soils of the upper Midwest. In either location, arborvitae vigor and growth will be aided by using Miracle-Gro annually. Just don't use fertilizer spikes.
Q: I have five-globe arborvitae. Every time we get a heavy, wet snow, the branches droop to the ground. Should I wrap them in burlap or is there something else I should do? (e-mail reference)
A: Go for the burlap when heavy snows are in the forecast. This practice has been carried out for decades because it works!
Q: I have four, small arborvitae. I assume it is too late to plant them this fall. Would I be better off to try to keep them in the garage and water them through the winter? (e-mail reference)
A: Plant them as soon as possible because the soil is still warm. As long as it remains above 40 degrees in the roots, they will function in getting the trees established by picking up some water and nutrients and growing somewhat. Protect them from exposure with coarse burlap before freeze-up takes place.
Q: Do you recommend Wilt-Pruf for arborvitaes? Last year, they died after winter. They are not very protected from the wind and snow. Would burlap work better? (Sioux Falls, S.D.)
A: Burlap would be better. The Wilt-Pruf label says, "When spraying on arborvitae, cypress, juniper, and cedar; be aware that if these species have not sufficiently hardened off for the winter whereby moisture retreats to the root system, moisture in plant cells could freeze and burst if early severe freezing weather should occur." We've had problems with arborvitae in the past because it sometimes doesn’t harden off sufficiently, resulting in winter damage.
Q: I have several emerald green arborvitaes that I would like to propagate. I doubt I would ever find this specific genetic tree again. I've been looking through your Web site and others, but can't find anything on how to propagate arborvitaes. Can you help? (e-mail reference)
A: Look again, but this time go to www.ext.nodak.edu/extpubs/plantsci/landscap/h1257.pdf. The site doesn't address the emerald green or other arborvitaes specifically, but the generic information also applies to this plant.
Q: I have three evergreen trees bushes or shrubs (I don't know what to call them) close to the house. They were here when we bought the house 25 years ago. Two have flat, soft needle formations spread out, such as a hand. The trees are producing some sort of seed on their sunny side. The other tree has short, spike needles and small, dark-blue berries. It also is bare on the side next to the house. One tree has grown taller than the eaves, so I want to trim it. Can this be done in the heat of the summer or should I wait until fall or spring? (Williston, N.D.)
A: It sounds like you are talking about junipers and arborvitaes. Pruning now, with the hot temperatures, is not the best time. You are better off trimming in early spring to give the cuts a chance to heal quickly.
Q: I have a question concerning arborvitae. We sold and installed 10 super-nice techny pyramidal arborvitaes last fall. The plants looked green and lush at the time. The client called me to take a look at the plants today. The arborvitaes look haggard. The plants have a lot of browning, especially on the south side. I suspect sun damage, although he sprayed them with Wilt-Pruf late in the fall. This problem seems to occur every year. What can be done about it? Is there a chemical, fertilizer or some product that could be sprayed on the trees to bring the plants back? Is it going to take wrapping them in burlap to protect them during the winter? (e-mail reference)
A: This is the most commonly asked question about arborvitae. It is winter desiccation that is causing the discoloration. For now, this is a problem your client will have to accept. In nearly every case, the arborvitae recovers. I would stay away from using Wilt-Pruf in the future because the product doesn’t seem to do arborvitae any good for some reason. A couple of tricks can be used before winter to help minimize winter damage. Don't baby these plants with perpetual watering right up to freeze-up and do not fertilize the plants any more than absolutely necessary. The objective is to get them "conditioned" for the winter by slowing or stopping cell growth, getting the cell protoplasm more viscous and less apt to be lost to winter desiccation.
Also, take some wooden stakes and build an open-top tepee around the arborvitae. In this case, build it along the south side of the plants to intercept the direct rays of the sun from raising the foliage temperature to the point of causing transpiration. These plants are native to North America and established ones put up with the continent's worst weather and barely shed a single bit of foliage. It is the overly cautious action with good intentions that we pursue the establishment and growth of these trees. We simply keep them too soft. I would advise that after August, additional water should not be applied. If it rains, so be it. By that time, the plant is reading the shortening days and beginning to close down physiologically for winter. We "confuse" the plants by attempting to overwater and using those blasted fertilizer spikes! I hope this explanation (tirade?) helps!
Q: I am getting brown spots on my arborvitae. These bushes have a gold tip on the end. (e-mail reference)
A: Based on the information provided, I cannot advise you. I suggest visiting my Web site on arborvitae at www.ext.nodak.edu/extnews/hortiscope/tree/arbrvtae.htm to see if you can find information about your problem.
Q: I've researched, with no luck, to find out if it is safe to have arborvitae in a horse pasture. (e-mail reference)
A: It isn't listed in any of my poisonous plant references as being toxic. Besides, the deer feast on arborvitae anytime they can find it!
Q: We are trying to decide if we should plant a thuja green giant or an arborvitae (can't decide on American or emerald). We're looking for a privacy screen from our neighbors. We have a fair amount of mild winds that tend to blow through. We have clay soil for the most part, but with some sogginess after heavy rains due to runoff. (e-mail reference)
A: Both of your choices are of the arborvitae species. Thuja plicata (green giant) is a cultivar of the giant western arborvitae. It grows quickly and has a broad spread. During the winter, the green color becomes a bronze. It regreens with the advent of warm, spring/summer weather. The green giant grows to a height of 30 to 40 feet and half as wide. What is being sold to you as an American arborvitae is probably the dark green American, also known as nigra. It supposedly will retain good color through the winter months, get 20 to 30 feet tall and 5 to 10 feet in width, and have a nice pyramidal form. The emerald arborvitae originated in Denmark. It grows to about 15 feet, with a 4-foot spread. It stays green all winter, tolerates cold in winter and heat through the dog days of July and August. Your choice depends on what you are trying to achieve, other than as a screen between properties. In my opinion, the nigra (dark green American) would be the best fit, but only you can make that determination.
Q: I have a row of arborvitae approximately 12 to 15 feet tall. My dogs chewed-off the bottom growth on several trees two years ago. I have since fenced off the trees and started nursing them with tree food. The trees are still alive, but look sickly and have produced no new growth. Is there anything I can do to bring them back to their original strength and stature? (e-mail reference)
A: If the dogs chewed off all the green foliage at that level, then nothing will grow back at that height. The trees should survive because of their size, but the chewed off stubs will remain just that. Sorry! Fertilizer will not restore the trees, so save your money.
Q: We planted arborvitae across a section of the yard close to a wooden fence. The plants did great for a few years, but last summer they began to thin. We fertilize the plants with Hollytone twice a year. At this point, they are extremely thin and no longer offer the privacy we want. Can you offer any advice to revive the plants? (e-mail reference)
A: Thinning of evergreen arborvitae foliage, without any visible disease or insect problems, is usually associated with environmental conditions, such as too much shade. If that is the case, you need to move the plants to improve sunlight penetration or pull them out because they will not improve under the present conditions. If shade is not a problem, then examine the planting depth. If they are planted too deeply or covered with too much mulch, then pull some of the soil or mulch back to the crown, which is where the stem meets the roots. Fertilizing twice a year is not necessary. Save yourself money and time.
Q: We have five emerald arborvitae that have been diagnosed with phomopsis twig blight and alternaria as a secondary infection. Do you know of any arborvitae varieties that are not susceptible to these diseases? (e-mail reference)
A: The Nigra (dark green American) and Techny (mission) are noted for their cold hardiness and disease resistance. Keep in mind that it is not entirely the fault of the host that it became infected. Environmental conditions and planting quality play major roles in increasing susceptibility to pathogens. Be sure the soil is well drained, the plants get as much direct sunlight as possible and the area has good air circulation. Whatever you do, do not allow the foliage to be impacted by water from an automatic irrigation system!
Q: I have several arborvitae that need to be cut down a bit. Would it be OK to cut them in half? If so, what is the best way to do it so they will survive and look nice? (e-mail reference)
A: Do it in the spring, before new growth appears. Cut them back without leaving a bare stub. As for looking nice, try to remember your boot camp GI haircut. Not too many of us thought it looked nice, but the hair grew back and did look nice! In other words, don't expect it to look like a silk purse upon finishing. However, with flushes of new growth, it should look decent by midsummer and continue to improve from that point on.
Q: I have several arborvitae I use as a hedge. Deer ate them and now there is nothing left but a tuft on top. Do they have a chance to survive? If so, what should I do to nurse them back to health? Should I fertilize now or wait for spring? Also, should I put up protection for the remainder of the winter, even though there is nothing left to eat? I hate to replace them because they were very expensive. (e-mail reference)
A: You want to purchase a material known as Plantskydd, which is the best deer repellant on the market. It is a powder that needs to be mixed with warm water and then applied. It will keep the deer from continuing to feed on what is left. Other than this, there is nothing you can do right now. In the spring, see if any new growth breaks out. If it does, will the form be what you want in your landscape? Probably not, so you likely will need to replace these trees. Knowing what you do now, take proper protective action next fall.
Q: Could you please help me with a problem? Last year I planted six midget arborvitae bushes. They looked great for several months. Last fall I noticed the side of one turning a rustlike color. Later that side became brittle and died. This spring I noticed several other bushes with scattered areas of the same thing. What can I do? I have heard about using Epsom salt. Please help! (e-mail reference)
A: I don’t know of a rust fungus that hits arborvitae. Cedar apple rust refers to the “cedar” as being a juniper, not a thuja (arborvitae). What your plants might have is juniper blight (Phomopsis blight). To control it, prune out the infected branches and spray with a fungicide such as Benomyl, Funginex or Cleary’s 3336. To apply the fungicide, use a sticker-spreader.
Q: I recently put in a privacy fence that at the sloping end of my property does not give much privacy. My plan is to plant a row of arborvitae along the back fence line. The lawn where these will go is well-established and I have read that a couple of inches of mulch is a good bed covering for these trees. What should I do to the grass before planting and mulching? Should I lay down plastic to keep the grass from growing through the mulch? Should I use a sod cutter to remove the grass? The bed for these trees will be about 5 feet off the fence. Is this far enough away from the fence for healthy growth? (e-mail reference)
A: A 5-foot spacing away from the fence is very adequate for normal, healthy growth. As for the turf area where they are to be planted, the best procedure is to kill the grass with Roundup. Dig the holes for the trees and cover the entire area with 2 to 3 inches of mulch. Don’t cover anything with plastic or any other weed barrier before putting the mulch down. The fact that the turf area was killed and not disturbed, other than for planting, will result in a good weed barrier. Weed seeds blow in and are deposited by birds anyway, so there is no such thing as being 100 percent weed-free.
Q: My husband recently transplanted 16 arborvitae trees to underneath our deck. He had to trim the trees significantly to make them fit. Because they are almost touching the underside of the deck, I don’t see any room for growth. Will this kill them or can we keep them trimmed? (e-mail reference)
A: Under the deck is a bad idea for these plants - sorry! If you want to keep any plants under a deck, they should be adapted to shade conditions and be selected for maintaining a size that is desirable for the space. Continuous pruning under such conditions is not the best treatment for these plants, either.
Q: Two years ago, I activated a well, hoping to cut down on the water bill. Instead of saving, we lost big time. The water tested 2,300 parts sodium chloride and 100 parts sodium. You can imagine what happened. We lost 38 of the 89 arborvitae trees and close to 30 flowering plants. I replaced all the badly burned shrubs. Is there any help for the remaining arborvitae? I’ve been giving them Miracle-Gro. They are coming back, but the bottoms are still bare (where the water was hitting them). (e-mail reference)
A: There is always hope, if they are showing signs of response. Keep up the treatments, but don’t overdo it!
Q: I have several arborvitae lining my patio that have been decimated by deer. It there anything I can do to restore them? (e-mail reference)
A: Just try to keep them healthy. If they are going to recover, they will. Next year spray a deer repellant such as Hinder or Plantskydd to keep away the deer.
Q: I have a row of emerald arborvitae on my property line. After a bad ice storm this winter, I noticed several were bent over nearly to the ground. Should I try to straighten them or give up and have them replaced? (e-mail reference)
A: Go ahead and straighten them as long as the trunk is not broken or frozen. If you are staking the arborvitae to straighten them, remove the stakes after new growth is observed. They should stay upright after that.
Q: We have two arborvitae next to our front door. They are about 8 feet high and look very out of place because of their height and location. Is it possible to cut them down significantly? (e-mail reference)
A: It is done all the time! If done properly, no one will ever know that the plants were a lot taller.
Q: I planted several arborvitae trees in 2003 that are doing fine. I now want to replant some of them to make more room for a pit greenhouse. I’ll be using 4 feet of banked soil. Can I plant these trees up to the banked soil and trim the south side of the trunks as they grow? My concern is that the tree will suffer if it is up against the banked soil. My plan is to have an underground path from my basement to the greenhouse with about 2 feet or more of soil on top. How big is an arborvitae root system? How deep do they grow? How close can I plant these trees to my underground path or pit greenhouse? (e-mail reference)
A: “Up against” anything, such as a wall of soil, wood, brick, etc., can cause problems. Like any other plant, arborvitae need and better thrive when given breathing room. I don’t know the architecture of your dirt wall. If the wall is a straight vertical, it will cause problems. If the dirt wall is sloped sufficiently, it may not cause any problems. In fact, you could plant the small trees into the lower part of the bank.
Q: I’m landscaping my front yard. I have a large arborvitae as a foundation plant that my husband loves, so I want to make it work with the new plan. The plant is in good health, but I think it’s ugly and can’t see any way that it’s going to work with other perennials in any kind of landscaping plan. Can I trim the lower branches to give it a different shape, or would that leave me with an ugly mess? How close to the foundation can I plant an amur maple? I’m concerned that the roots and branches have enough room for proper growth, but want it as close as possible to the house. (e-mail reference)
A: Arborvitae easily can be pruned. Whether it will be an ugly mess is something only you and your husband can decide. Amur maple does not have an aggressive root system, so you can plant it fairly close to the house. Keep in mind that the tree will form a nice canopy at around 20 feet, so you want to give it room to do so without you having to do a lot of lopsided pruning to keep it from affecting the side of your house or dropping a lot of leaves into the rain gutter. Mine is planted about 12 feet from the house. We have had to do occasional pruning to keep the branches from damaging the shingles.
Q: My husband and I planted over 20 techny arborvitaes two summers ago. They have been doing just great and gave us the privacy we needed for our backyard and pool area. This past spring we have noticed that the trees have produced mini-like pinecone looking nuggets, which are bronze in color, all over its branches. Some of them dried up and fell off, but most have remained. Could it be they are lacking acid? What can we do if this is not the normal growth process? We have noticed that there is plenty of new growth, despite the problem. We would hate to lose them because it was a very costly project. (e-mail reference)
A: You are worrying needlessly. The fruiting bodies are an indication of the plant’s maturity. Some are more prolific at producing (think hamsters versus pandas) than others. As long as the plants are maintaining their rich green color and new growth, you have nothing to worry about.
Q: I have 15 arborvitae that were planted 10 years ago. Suddenly, most of them turned brown halfway up and appear dead. Amazingly, only one side of the trees turned brown and the other side (facing my neighbor’s house) is green! My tree company says they did not spray anything harmful. Only 10 of the 15 trees are brown. If they did spray something, I would think all the trees would be brown. I don’t know if our rough winter had anything to do with it. Is there anything I can do? (e-mail reference)
A: The tree company may not have intentionally sprayed the trees with anything harmful, but there could have been some residue from another client where they did use something that would have been toxic. It may have been used up by the time they got to the eleventh tree. Also, do you have a lawn care service? Are the unaffected ones in the shade and the affected ones in direct southwest sunlight? These are all only guesses. Don't give up on the trees. I've seen some that I didn’t think would make it, only to be pleasantly surprised at their total recovery.
Q: We are in the process of planting emerald green arborvitae. What kind of mulch would you recommend? (e-mail reference)
A: A bark or peat mulch no more than four inches thick. Never use stone mulch and do not put plastic over the roots to keep the weeds down.
Q: We want to purchase arborvitae to screen a storage area and would like some advice as to the best type. We would like it to grow wide, but not terribly high. One store has emerald and techny, but the techny costs slightly more. Is there another variety you would recommend? We have one on the other side of the yard, but don't know what it is. We would like to match it if possible. (Minneapolis, Minn.)
A: What you have and probably want is the techny arborvitae. The emerald is noted for its narrow upright growth, while the techny is noted for its broader growth.
Q: I have seven global arborvitae shrubs growing in my yard. Half of them are about 20 years old. The shrubs have gotten really shabby looking in the last few years. I water them in the summer. I used fertilizer spikes last spring and this spring, but there doesn't seem to be much growth. I trimmed the shrubs two years ago. Now the bottoms look very thin. A snow plow broke the top off one plant two years ago. It has never grown back. Is there any hope for these shrubs or should I dig them up and replant? What do you suggest for fertilizer and winter support against ice and snow? (e-mail reference)
A: Never use fertilizer spikes on any plants. Spikes are a waste of money and don't do the job. There are better and more economical ways to fertilize plants. Fertilizing should be done if needed, during the beginning phase of active growth using a product like Miracle-Gro. Based on what you have told me, it doesn't sound too good for the trees. If they don't respond to basic care and they are not complimenting your property, get rid of them. For winter protection, use a strong oak stake tied in to keep the tops from being crushed under a heavy snow load.
Q: Two years ago, I planted six pygmy globe arborvitae in front of our church. They are spaced about seven feet apart. It is 36 inches between the church and sidewalk and they are on the east side of the building. Last year one started turning brown. I replaced it a few days ago. Now the other five are starting to turn brown. I have tried to water about every 10 days. I sprayed with Malathion and applied Miracle-Gro twice last summer. The ground is covered with plastic with small rock on top. (Kathryn, N.D.)
A: Your problem is the plastic/rock cover. Take it off as soon as possible and leave the soil bare. Mulch with bark (2-3 inches) if you have to. The rock/plastic combination deprives the root system of air and causes a gradual plant decline and death.
Q: I just planted a row of six foot emerald arborvitae trees. A few of the trees are turning brown at the top. Is this something to be worried about? The landscaper fertilized them and I water them once a week or so. (E-mail reference)
A: That discoloration you are seeing could be the result of transporting the plants to your site for planting. Many times the landscape crews (I used to be on one!) will drive too fast, and the plants lose moisture. If new growth doesn't cover it up, I would contact your nursery to see if some replacement options can be worked out.
Q: My husband and I are going to be planting five emerald green arborvitaes in our backyard. We have never planted trees like this before, so we are not sure what we need to do. Our soil is somewhat sandy, but while digging I found many huge earthworms, which makes me believe that the soil is good. Any information and help would be greatly appreciated. (E-mail reference)
A: Plant them in the soil you describe. Do not use fertilizer and water in well. The top of the rootball should be just below the surrounding soil surface. The burlap and twine should be cut off the stem after the trees are placed in their planting site. Mulch with peat moss and water once a week unless you get adequate rainfall.
Q: I am moving into a new home that has arborvitaes around the patio for privacy. There are some areas that are dead and no longer green. Can I cut it just below the dead zone or should I just cut into a green area in late spring? (E-mail reference)
A: At your earliest convenience, cut back to where there is some green. Never leave a stub.
Q: We have some type of arborvitae on the south side of our home which was here when we came. They are about 18 years old. They are about three feet from the foundation and are five to six feet tall with trunks about five to six inches in diameter. We are concerned about damage to the foundation of the house. Should they be removed? If not, should they be pruned? (Corsica, S.D.)
A: Arborvitae will not cause any damage unless you have a wet, leaky foundation. If they are complimenting the architecture of the house or providing some function, there is no need to remove them. Remove them if they are overpowering the house or looking ratty. They can be pruned in the early spring, prior to new growth.
Q: We have some emerald green arborvitaes standing by themselves at several corners of our home. We planted them about five or six years ago when they were four to five feet tall. They are now about seven feet tall and have filled out nicely. We have never trimmed them but probably should. This winter we had some heavy snowfalls. During one storm, the weight of the snow caused the branches to separate so they now flop to the side. Needless to say, they are not holding the tall slender shape they previously did. I used twist-tie wires to pull the branches back together with the hope they will strengthen and hold their previous shape. Did I do the right thing? Is there something more I should do to correct the problem? (E-mail reference)
A: You did the right thing. Eventually they will pull themselves up again provided the wood is not broken. You can also trim them lightly to lessen some of the weight.
Q: I have a row of arborvitae on my property line that is now as tall as the power line above. Should the tops be trimmed? Will it improve the growth below? Growth on the bottom has been dying as the trees have aged. Is it because of the height of the trees or a natural occurrence? If there is no way to bring this growth back, would it be harmful if I heaped up the lower area with mulch and wood chips? What is the best fertilizer for these plants? (E-mail reference)
A: The thinning out is a natural process of this species. Under cultivation, they usually top out at about 30 feet. In their native environment, they top out at 50 to 60 feet. The tops can be trimmed which often results in better growth below, depending on how close together they are planted. More thinning occurs if they are planted close together. If you bury the roots in mulch, you will very likely kill the trees by cutting off the air supply. It may also cause them to re-orient their roots upward into the mulch, which reduces the stability of the plant. These trees seldom need fertilization. If you think they do, an annual application of Miracle-Gro when new growth is just beginning will suffice.
Q: We have a 50-foot row of 20-foot high arborvitae that we use as a hedge along the south border of our property. They predated our arrival here so are likely about 30 years old. They were planted very close together. During our 15-year tenure we have taken a fairly laissez-faire approach to them. We trim back the tops to keep them away from wires and fertilize every two or three years. We have greatly enjoyed the privacy they provide. About ten years ago our neighbors to the south planted some evergreen trees about six to eight feet south of the hedge. They are now about the height of the hedge. Our problem is that the hedge now seems to be thinning out, particularly at the two to eight foot level. Is the shade produced by the evergreens affecting the arborvitae? Would trimming the hedge (top or sides) help renew its thickness? Would it help if we fertilized more often?
A: It is very likely the shade from the adjacent evergreens is causing the thinning out problem. Fertilizing and pruning the top will not help in thickening up the lower portion of the hedge. If you have the space, I would suggest getting a shade tolerant species such as mugo pine or Canadian hemlock (depending on where you live) to plant in front of the arborvitae to help provide some privacy for you.
Q: When is the best time of year to trim arborvitae globes to keep them from growing out of shape? (E-mail reference)
A: The best time to prune arborvitaes is just before new growth begins in the late spring but do not cut it back beyond the green foliage. Doing so will condemn that spot to be bare forever. This is perhaps one instance where an electric hedge shear could be put to good use!
Q: My wife and I recently planted eight emerald green arborvitaes. After three weeks all eight appear to be dying. They are browning in some spots and look stressed. We watered each of them for about 10 minutes after planting and about the same for three of the next seven days. The nursery where we bought them said the effects of overwatering are identical to underwatering. That sounds crazy to me but I don't want to kill what should be a beautiful tree. We have since cut back and let nature provide the water. It's rained about three times in the last two weeks. Should we water more than this or continue to let nature provide the moisture? Should we fertilize? (E-mail reference)
A: The nursery is right. The symptoms of overwatering are identical to underwatering. More trees, shrubs, and houseplants are killed from overwatering than all other problems combined.
Effective communication from the nursery to the customer should be: "water thoroughly upon planting then water thereafter as needed depending on soil and environmental conditions. At no time should the soil/rootball be kept soggy. The plant should be dried to the point of dampness to the touch before a complete re watering takes place. This regime should be carried out at least through the first year. Soil moisture should be monitored closely for the next two years with corrective action taken as needed." Fertilizer will not correct the problem. There is a chance the arborvitaes will recover if you manage the soil moisture as I have outlined.
Q: I have four arborvitae planted around the front of my house. They have turned brown from the bottom to almost the middle. They looked fine before winter set in. We have a little mutt and I believe he has made a habit of urinating on them. Is it possible my dog has affected my plants or are they shedding? (E-mail reference)
A: There is no return from foliage browned by dog urine. Either accept the condition or train your pooch to go somewhere else.
Q: I'd really appreciate it if you could help me find a cure to my ailing emerald arborvitae. There are some spots that have turned literally black (as if it's burning) and some that are brown. Why are the leaves turning black and how can I prevent it? Also, you mentioned that spikes are not good for the roots. Does that mean I have to dig out the roots? (E-mail reference)
A: The blackening is likely due to a bacterial slime from too much watering or too wet a season. Some of the browning could be due to normal needle decline on the older growth. It could be winter burn if it is on the outer growth. It depends on how long you have had the spikes in. If you just put them in this spring, then you can remove them. If they have been in since last year, then it isn't worth it.
Q: I have a row of 30 emerald green arborvitae. They are planted along my property line about five feet from the edge of a paved parking lot. The tips on several of the trees are beginning to sag and look wilted. The trees look like they are being bent over from the weight of heavy snow weight but without the snow. Some of the tips of the needles have browned but that might be from a winter kill. There is new growth evident at the tips on top. Could my problem be salt damage or a fungus? (E-mail reference)
A: Thanks for the good description. From what you describe, it appears you have a high soil salt problem. To confirm, take a sandwich-bag sample of soil from the base of the plantings and send it to the Land Grant university in your state asking for a salt level test. I'm willing to bet it will come back very high in soluble salts. About the only thing you can do is try and leach the salts out with high quality water. Try to do that a couple of times a week for a month.
Q: I would like to plant an evergreen hedge for privacy. The two-story house directly behind me is quite a bit higher than my house and appears to look down on my deck and house. I don’t have a lot of space to work with between properties. Spruce and pines would be too large and would hang on my neighbors’ property. A local landscaper recommends techny arborvitae. What would you recommend? Does Arborvitae attract a large number of flies? Does this occur all growing season? This would be close to my deck and outdoor eating area and I don't want to create a problem. I've read where nigra arborvitae are taller than techny. Are they just as durable? (Bismarck, N.D.)
A: Nigra arborvitae does get taller, reportedly up to 30 feet and are said to be very durable. Fly attraction should not be a problem but insects will naturally gravitate to any shrub or hedge for shelter and food, so you will not be bug free.
Q: I planted five arborvitae in mid-August of last summer. We had an unusually hot and dry summer, so I watered the plants frequently. They seemed to be doing okay, but toward fall the leaves closest to the truck turned brown and died. The plants seem to have survived our harsh winter. I don't know if they are just dying a slow death and I should start over or if I should give them more time. If they are worth saving, should I pull off all of the dead foliage and branches closest to the trunk then apply some Miracid? (E-mail reference)
A: The dropping of the dead foliage nearest the trunk is normal, just like us shedding our old hair. Don't pull any of the foliage off because it will defoliate at its own pace. In the meantime, it would not hurt if you want to apply some Miracid a couple of times this summer.
Q: We are planning on planting 100 feet of American arborvitae along our property line this year. How much growth can we expect each year? Can they survive in our area which is zone 3 in Canada? What is the best time of year to plant? ( Edmonton, Alberta, Canada)
A: The American arborvitae cultivars techny and Brandon are the hardiest, showing the most resistance to winter burn. They should do all right in your area, as long as you spray the foliage with an anti-desiccant prior to winter's arrival. Both are hardy down to -40 degrees F. (zone3).
Spring is best time to plant them -- whenever that arrives in your part of North America.
Q: My husband and I planted six arborvitae last summer that looked great. This spring we have noticed that the bottom foliage has turned black. It almost looks like black spray paint or tar. It is on most of them and goes up the tree about 12 inches. They are planted right next to a field where corn and beans are planted and fertilizer is sprayed. I wouldn't think that would be the problem. (E-mail reference)
A: I would suggest taking a sample to a plant diagnostic lab at your local land grant university. There are just too many things that could be causing your problem for me to try to answer in this column.
Q: I have a 150 inch long wall of arborvitae along my property. They are approximately 80 inches tall. I would like to trim the height back to 72 inches. Can I do this without harming the shrub and when is the best time of year do it? . (E-mail reference)
A: The arborvitae can be pruned anytime - spring, summer or fall, as long as all of the wispy green growth is not removed. If you cut back and remove all the foliage in a spot, that spot will be there forever! These are one of the few woody plants that respond well to shearing. Just be sure to try and maintain the natural shape.
Q: The front of my lawn is shielded by what I am told are arborvitae. I live along a major road so they hide my view of the traffic and cut down the noise. I got a local tree trimmer to give me an estimate for trimming them into shape. I was surprised when he said that he wouldn't do it! He says he'd kill sections of the tree or he wouldn't be able to shape them enough. He said that arborvitae only likes to be trimmed in the sections that are growing. Is this true? (E-mail reference)
A: I am glad to hear about honest tree trimmers whenever I can. There are too many individuals out there with chain saws and pickup trucks who incorrectly call themselves by that name. The beauty of arborvitae plants is that they need little pruning. They should never be cut back beyond their green leaves. A bare spot created by pruning is a bare spot forever and your tree trimmer knew that. Good for him!
Q: I have a slightly overgrown arborvitae under the corner of my roof but it gets damaged every year from ice run-off. I'm wonder if I should wrap it in burlap or tie it in some manner so it doesn't get beat down by the run-off. How long should I leave it wrapped? Is there some better or easier way? (E-mail reference)
A: Try to locate some 6 foot one-inch by one-inch oak stakes and tie them to the trunk of the arborvitae with rage to give it benign support. That should take care of the problem. Complete wrapping is not suggested.
Q: I have a question about pyramidial arborvitae. I'd like to put several of them between my house and the neighbor’s. However, there is only about 10 feet between the houses and he is concerned about the root system finding its way into the plumbing. He had some overgrown mountain laurels removed from the same location for those very fears. Was he right? What are the chances of that happening with pyramidial arborvitae? And what type of root system do they normally have? (E-mail reference)
A: Unless the plumbing is leaking, no one has anything to worry about. Roots will not develop where there isn't a good balance of air and water, and arborvitae are used as "foundation plants" in basic landscape projects because they do not have roots that cause problems. Plant without fear.
Q: A lady has a big evergreen but she calls it an overgrown arborvitae. It is red inside and the foliage is red. She watered it all summer. What's happening and can it be saved? (Linton, N.D.)
A: It sounds like rust. Just a guess but I believe it can, if all else is healthy. Spray next spring with Bordeaux mix. It should keep the pathogen in check.
Q: This spring I planted 100 feet of 6-foot arborvitae trees to hedge my yard. It has been a dry hot summer but I have watered them weekly. I have also applied fertilizer for acid-loving evergreens. From August through now, a large amount of foliage has turned brown. There’s lots of new growth. I cannot see any evidence of insects (i.e. brown spots). What is the problem? (E-mail reference)
A: The dead foliage you are witnessing is from the interior part of the plant and is simply the oldest foliage going through normal senescence. This takes place in the autumn months and is sometimes more noticeable than at other times. You have nothing to worry about, just don't let the planting go into the winter dry. Keep up your watering regime!
Q: I just read your response to a reader about not using fertilizer spikes for arborvitae bushes. You mentioned that they are a bad investment. You said she should use Miracle-Gro. Is that your feeling for evergreens or arborvitae in general or her situation only? I have used spikes in the past on small evergreens but am wondering if I should stop doing so. (Fargo, N.D.)
A: Here is my take on fertilizer spikes. Years ago I conducted a study on spikes and found them to be more damaging to the immediate roots then a benefit. Also, they were losers when calculating the value received compared to the price paid. I tell many people, if what you have been doing is working well for you, then stay with it no matter what I believe or say.
Q: I have a couple of aborvitaes in front of the house and they are just loaded with flies. Could you tell me why and what I can do to get rid of the flies? (E-mail reference)
A: The flies are getting some nectar or exudate from your tree. You can get rid of them with a spray of Sevin insecticide.
Q: I was wondering how I could propagate arborvitae trees from either seed or cuttings. I have heard they are easy to grow from cuttings taken in winter and potted up indoors. Is this true? How hard are they to grow from seed? (E-mail reference)
A: Growing arborvitae from cuttings is so sinfully easy that it simply doesn't pay to try to grow them from seed. Just take cuttings about 6 to 9 inches long, stick them in sand under a mist system (or mist them frequently by hand) and in six weeks there should be an abundance of roots.
A: Unless you have very sandy soil, every other day is way too much water. Once a week until they become established is ample except under the worst conditions of heat, wind, or drought. Once established, they should get along nicely on whatever Mother Nature provides, unless it goes 30 days without any appreciable rainfall.
A: I suggest either the Emerald or the Brandon; both are more resistant to winter burn, and extremely hardy to -40 degrees F. Both get about 15 feet tall and a spread of 3 to 4 feet. You would want to space them about that distance apart (main stem to main stem) if you want complete coverage. Arborvitae are not fussy, being a standard landscape plant. They will grow well in your Wisconsin soil. I would simply give them a shot of Miracle-Gro at planting time, and keep them watered--not soaked - for the rest of the growing season.
A: The only mistake you made was in the order of operations. First of all, I have no idea why your landscape company told you to wait a year before adding mulch. I had my own business, plus I worked for four other contracting companies, and our policy was to always mulch upon completion of the plantings, with no negative effects. But first, we watered down every planting before applying the mulch. What you are experiencing now is the mulch's ability to shed water. I suggest pulling the mulch away from each plant, laying a soaker hose along the whole row and allowing it to run for an hour or so, then covering it with your shredded mulch, no more than 3 inches thick.
A: The pyramidal arborvitae may grow in your part of the country, but here are the caveats: Deer relish arborvitae, so make sure you do something to protect them if deer are common in your area, which I suspect they may be. Winter burn can be a problem if planted in an exposed location. For foundation plantings, an east or northern exposure--if not entirely shaded--will do well. Select cultivars that have proven to be more resistant to winter burn and are dependably hardy in zone 3, such as Brandon, Gold Cargo, Hetz Midget, Techny and Wareana.
A: I wouldn't advise doing what you are thinking of for a couple of reasons: The roots of the ash trees are going to be extremely competitive with those evergreens, which are going to have about a third to half of their root system left behind when they are spaded. Smaller plants grown in containers will have 100 percent of their roots and grow much faster than those that have been severed. Second, you are right about the expense! Save your money for something better. Just what I'll let you decide. For a "natural" look, why not plant some sub-canopy species like dogwood or honeysuckle shrubs? They will grow nicely, providing flowers and fruit which will attract the birds and butterflies and will not be subject to winter burn as evergreens would.
A: Based on the sample you sent, that is what the trees are--arborvitaes.
Q: I'm concerned with the arborvitae shrubs around our house. I soaked the roots pretty well around the first or middle of October and used a sprinkler can mixed with Miracid soaking the entire shrub. I was hoping that would take care of them until spring.
Due to the dry weather conditions, no snow or much moisture of any sort since, the plants seem to be turning rather dull looking. Sort of turning brown. What do you suggest I do? I've thought maybe about getting the water hose out and washing them off real good again, but don't know if that would be wise either. I've also been noticing that many of the red Cedars around town are sort of turning that color also. (Gettysburg, S.D.)
A: The late fall weather has been frustrating for many horticulturists because most plants are entering winter with inadequate moisture, but temperatures have been too low to effectively irrigate.
But, let's be optimistic! I recall several years ago that spring played a nasty trick by sending a Chinook wind through the state leaving all the evergreens fried. Everyone thought there would be wholesale losses, but there were no more than what normally occurs. Most recovered and looked good going into summer.
I suggest that the same will likely hold true for your evergreens. They have been around a long time and are fairly well adapted to our weather crazies (like we have become). Basically, you've done all you can. With our current light snow cover, this may provide the protection needed.
Q: I would like to grow a natural wall using North Privet or American Arborvitae. Would either of these grow well in Fargo? I would like them to be about 5 feet tall within five to six years. I am planning to purchase them from the Arbor Day Foundation and am assuming they will be 1 foot to 2 feet tall at the time of purchase.
Also, I planted gladiolas and
dahlias in my garden. How can I save these bulbs over the
winter? Will they survive in an insulated
cooler between dry peat moss in the garage? (Fargo, N.D., e-mail)
A: Both the privet and arborvitae cultivars would likely do well in Fargo. If you are getting them from the National Arbor Day Foundation, they are likely not going to be 2 feet in height, more like about 1 foot high. But once established, either should grow quickly.
The dahlias would likely make it insulated in your garage, but I'm not sure of the glads. You might be better off keeping them dry in a 55 F location. Dust them with sulfur powder to keep diseases and insects from getting to them.
Q: At what time of the year does one trim global arborvitae? Should Potentilla be cut back and when? Does one cut back Clematis in the fall, spring or not at all? (Grenville, S.D.)
A: The best time to trim your arborvitae is in the spring when active growth can take place. Cut the potentilla back in early spring prior to leaf-out. Most clematis varieties bloom on new growth produced in the spring. Cut back in early spring to about 6 inches of old growth remaining.
Q: I'm having a problem with my arborvitae. What do you advise? (Hoven, S.D.)
A: Your arborvitae leaf has a minor infestation of scale, an insect whose mouth parts allow it to pierce and suck. In low numbers it presents no problem, but I'd suggest you monitor their population and prune off any branch tips where you find them getting started. Resist spraying for now, as natural predators may do the job for you.
Q: I have a problem and am enclosing a photo. We have some arborvitae that look bad. When we moved here several years ago, they looked nice and green (they had been shaped round) .
We gave them a little fertilizer each summer, and I did a little trimming. (Munich, N. D)
A: From a photo only, it is very difficult to tell. It could be winter desiccation or saltburn from deicers.
Arborvitae are fairly durable plants for our region. I suggest waiting 30 days to see if you get a positive response to your fertilization. The plant often outgrows the problem.
If it doesn't look any better by the end of the month, then send me a sample.
Q. Enclosed is a sample of an arborvitae that is 20 years old. Pictures are also enclosed. There is a certain amount of natural needle cast that is taking place now, but there seems to be something else involved with this specimen. The lower portion of the plant is completely void of any needles at all. Could it be needle and twig blight?
As usual, I would appreciate any help and/or information you can supply on the subject. (Sidney, Mont.)
A. The major problem is crowding, causing low light and, therefore, defoliation. The plants have become grossly overgrown, burying the house. They should be removed and the landscape rejuvenated.
Q.I am writing again! I have sent a sample from a perennial flower plant. It has done well for two years. Now this summer I noticed one plant was all brown and gone seemed like overnight. Now, I see another plant is doing the same thing. What is the problem?
I also seem to have trouble with petunias. The larger sample has light green on the leaves. I am afraid they are going to dry up again. The smaller sample is from a plant that just seems to sit there. What is the problem?
I have sent a sample from our arborvitae bush. We have other bushes in front of the house. This is the only one that has the "seeds." Why? Also, when is the best time to trim arborvitaes?
I really appreciate your column in the paper. Thank you. (Munich, N.D.)
A.Your samples arrived along with your questions, but the first one had rotted and was beyond identifying or diagnosing.
Try fertilizing your petunias with a water-soluble material like Miracle-Gro. If that doesn't color them up and stimulate growth, nothing will.
Since arborvitae are monoecious (separate sexes on the same plant) I suspect that the one you are concerned with had an over-abundance of female flowers to produce so many cones. It could also be that the other plants are dominated by male flowers, which do not produce cones.
Prune arborvitaes anytime in spring, summer or early fall. Just be sure to leave some wisps of green shoots with each pruning cut to avoid permanent bare spots.
Q. I have a Globe Arborvitae that has a brown bud-like growth which has been present for the second year. The plant looks sickly and is turning yellowish-brown, although there are still some healthy looking branches left. It appears to be some type of disease. I have been on the verge of digging it up and starting from scratch again. Do you have any suggestions as to what the problem is and what can be done with it?
I have enclosed a couple samples for you to examine. Thanks for any help you can give. (Center, N.D.)
A. Nothing to worry about--that is just the arborvitae "fruit" or seeds.
If it is producing heavily, that is often a sign of plant stress, not at all unusual in North Dakota. You might try fertilizing with Miracle-Gro. If you are using plastic mulch in your planting beds, remove it--the roots need air.
Consider relandscaping with something different. Refer to the circular H-958, "Landscape Ideas for North Dakota Homeowners," available from any office of the NDSU Extension Service.
Thanks for writing.
Q: I have a row of 35
arborvitae (emerald I think). Upon inspection I have noticed that
they turned brown within the middle leaving piles of dead needles.
have noticed that some of the exterior tips have started to turn brown as well. I fertilized using a common brand called Woodacre. I then proceeded to apply a layer
of cedar mulch. Unfortunately this is the extent of my knowledge. I am lover of all trees and flora and such and would hate to see these once beautiful trees wither
and die, especially if there is a simple remedy. I am aware that there are many afflictions that can harm these trees, from over/under watering to diseases and insects.
I am hoping that I might have a common problem such as watering habits. Sorry for the limited information but I am hoping you can give me some insight to the
health and care of my trees. They have been in place for three years now and have grown to about 7 feet. (Long Island, N.Y., e-mail)
A: You probably have nothing to worry about. First, the accumulation of dead foliage in the middle is normal. "Evergreens" also lose their needles;
some over a period of several weeks, others over a much shorter period, depending on the current environmental conditions.
Second, the tip burns could be the result of some esterification of volatiles from the cedar mulch. If the cedar had not sufficiently aged before being used
as a mulch, that could be the problem. If it appears to progress, I'd suggest removing the mulch and stockpiling it for another season, then spread it
Q: I have several questions for you in regard to trimming and transplanting my 2- year- old Techny arborvitae and some other plants. Can you tell me when and how to trim them so that they are not too high or big around? Can I transplant my daisies this fall, and also my dianthus? Should they be cut down after blooming and if cut off will they bloom again in the same season? Can I move my aster now and transplant them? How do I go about digging up my bleeding heart and transplanting it and when? When can I trim my Vanhoutte spirea hedge? If I do it this fall will it hurt or delay their blooming in the spring? When should potentilla be trimmed or transplanted? (Hannaford, N.D.)
A: Wow! I suggest a course or two in horticultural practices. You asked a lot of questions so I’ll be brief to get all the responses in a reasonable space:
1.Arborvitae -- prune in spring before new growth emerges. You can use a hedge shear (most people do!) or you can trim them by hand.
2.Yes, on both the dasies and dianthus.
3.Cutting them back after initial blooming will work with dianthus to give a repeat bloom; it may or may not with dasies.
4.Move the asters in the early spring.
5.Go ahead and transplant your bleeding heart. Locate the crown, dig carefully around it, lift and divide the crown into logical sections (two to four).
6.Pruning the VanHoutte hedge now will eliminate most of the flowers next spring. Pruning right after they flower will not. Woody shrubs are best pruned selectively in the early spring to reduce stress and enjoy the flowers.
7.Early spring on the Potentillas.
Q: I purchased eight arborvitae trees a year ago last spring. These trees were about 4 feet tall. What I noticed shortly after the landscaper planted them was that the root ball was exposed to about 4 to 6 inches on most of the trees. I have lost three of them so far, and when I complained to the landscaper he claimed there is nothing wrong with the root ball being exposed. Common sense tells me that the roots would dry out and the tree would die. What do you think? When a new tree is planted should the entire rootball be below the soil? (E-mail reference, Chicago, Ill.)
A: Your common sense is correct. B&B (balled and burlaped) trees and shrubs are dug from a nursery where the roots are not exposed. The top of the rootball is the top of the root system, and should be planted at grade level -- certainly not above it, and not below it. I don't know the value of what you had planted, but it should be worth a small claims court action. Document everything as carefully as possible -- take photographs, seek a consulting arborist or horticulturist, and if necessary, a lawyer. Arborvitaes are usually crowbar tough, bread and butter plants to use in the landscape, usually with no problems. A loss of almost 40 percent of the plant material is not acceptable in a landscape job. Something wasn't done right.
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