May 24, 2001

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: We wish to plant a couple tomato plants on the east side of our garage. We realize this is not an ideal area for tomatoes since they will only get full sun in the morning but do not have yard on the south or west side to plant in. What would you suggest we add to the soil to prepare it as best we can for the young plants? Peat moss? (E-mail reference, Aberdeen, S.D.)

A: Not to worry. Tomatoes will do well with east sunlight against a home. I have seen it at least a half-dozen times. The early morning sun dries the foliage, the sun light and heat reflect from the side of the building, the plants get at least six hours of direct sunlight most of the summer, and they are spared the destructive heat of the late afternoon sun. Working sphagnum peat moss into the soil each year prior to planting can do nothing but improve the growth and production of your plants.

Q: I have trouble with my poplar trees’ roots being above ground (we bend more lawn mower blades). Do they have to be above, or can we have dirt brought in to cover them? Would it be wise to cut them down or top them? (E-mail reference)

A: If you can, convert the area that is "rooty" in your lawn area to a flower bed. If this is too extensive, you can cover the roots with a couple of inches of topsoil, but the roots will simply migrate to the surface again in a few years. If you don't like the trees, take them out. Life is too short to suffer because of obnoxious roots. You can plant many other trees that will not give you such a problem.

Q: I have a problem with borers in my lilacs. I plant a lilac every year, but every year I lose one to borers. What can I use for preventative measures so I don't lose any more? The borers are always at the base. (E-mail reference)

A: Spray the base of your lilacs with either Dursban (chlorpyrifos), Lindane, or permethrin (Astro), beginning in mid-May at three week intervals, three times. Try to grow your lilacs in such a way that they are not stressed.

Q: I have access to several bags of "decorative" redwood bark. Can I use it as mulch (raking it off at the end of the season) without harming the soil or vegetables? (E-mail reference)

A: It shouldn't hurt anything as long as it isn't placed around the plants in excess. Two to 3 inches should be all right. Don't put it directly against the stems of the plants. Leave about a 1-inch clearing to prevent disease girdling the stem from continuous moist contact.

Q: I have a beautiful lilac bush I want to get a start from and add more lilacs around my 5 acre yard. What do I take from the plant to make a start? Can I mix lavender and white lilacs? How long does it take a start to root? I have a green thumb in the garden with seeds, but this is a challenge for me. (E-mail reference)

A: Lilacs can be started by digging suckers early in the spring before leaf out, or after the leaves have matured. They do not root well from cuttings, so I do not suggest that. They are usually very accommodating about sending up sucker growth, so you should have lots of material to select from. Color mixing makes no difference, so go according to your interest and taste.

Q: My in-laws have a number of chokecherry bushes on their farm. Last year they noticed some type of black "growth" forming on the branches of the bushes. The affected branches die and eventually the entire bush dies. I love my mother-in-law's choke cherry jelly and I don't want to sit by and let the bushes die. Do you have any idea what the disease is and how we can treat it? (E-mail reference, Nebraska)

A: The disease is a fungus known as black knot that is sweeping across the prairie states. Pruning it out and spraying with lime-sulfur while still dormant will help. If the trees are in leaf/bloom now, then get right on them with a product known as Cavalier. Spray several times and keep the knots pruned out. Good luck. Once this disease gets a foothold it is often hard to control.

Q: I have quite a large iris flower bed. I seem to be losing a battle with the dandelions taking over. Is there anything I can use to get rid of the dandelions that will not affect the Iris? We get our lawn sprayed each year for dandelions and it is pretty well clear of them. My husband thinks we should spray the iris with the same type of weed killer late this fall and see if it would stop the dandelions from growing. I am afraid it will kill the iris. What do you suggest we do? (E-mail reference, Geneva, Iowa)

A: I'm afraid that the only post-emergence herbicides I am aware of that can be used in an iris bed are for grassy weeds, not broadleaf ones like dandelions. Goal is a restricted use pesticide (RUP) that is cleared for iris. Find out if your lawn care operator is qualified to make such an application.

Q: I was wondering what I am doing wrong with my cala lily. About two months ago I brought two cala lilies out of dormancy. They have been thriving until recently when the leaves on one cala lily started getting yellow tips and now some of the leaves are all yellow, but the other one is doing just fine. They get treated the same and get the same amount of light. Neither one has bloomed yet. Could I be overwatering?

A: I doubt the problem is overwatering with these plants, as their media needs to be kept constantly moist. If they are both in free-draining containers, then I suspect that the problem could be that one is salt sensitive, and is showing it, while the other is not as sensitive to the salts. You might try watering the one showing the symptoms with some distilled water to see if it begins producing growth that is not burnt or yellow on the ends. If that doesn't change things, then I suspect root rot, and you might as well dump it.

Q: In late spring and summer the most incredible fragrance comes from these trees down the block. I took a branch with flowers to a florist to find out what kind of tree it was. He said linden. A quick search on the Internet revealed that there are different kinds of linden trees. Can you point me in the right direction to find out exactly what type of linden tree these are and how I might someday be able to fill a backyard with them? The scent is so addictive I have become obsessed. (E-mail reference, Chicago, Ill.)

A: Linden blossom fragrance can create a fantastic environment. You'll make all kinds of points by planting a little leaf linden. Some of the cultivars to consider are Greenspire, Norlin and Shamrock. American linden cultivars to consider are Legend, Redmond, and Sentry. I suggest visiting a local garden center to see what they have available and make a selection. You cannot go wrong with any of these that I mentioned. They simply have different forms of growth and vary in eventual height and spread.

Q: I have a chenille hanging plant and would like to know if I can bring it into the house when the weather starts to get cold to keep it all year around. What would be the care for that? Does this plant go to seed in the fall so I could collect them? (E-mail reference)

A: Yes, chenille plants make excellent houseplants. They need strong light through a filtered shade. If the light is inadequate, then the plant will become spindly and not flower. Keep it in a warm location away from cold drafts. During winter, cut back on the watering, keeping it just wet enough to prevent the soil from drying out. Chenille plants do not age gracefully, so begin taking tip cuttings in the spring and rooting them. Discard the parent plant when it no longer produces decent flowers or looks poorly.

Q: I have a 3-year-old Meadowlark forsythia that is blooming very nicely at the moment. I am wondering about its growth habit and how I should prune it. It is about 3 to 4 feet tall now. does this shrub sucker or does the growth emerge from the common trunk? I have plenty of space and would be able to accommodate a very large plant. What is the best way to prune to encourage growth in width as well as height? (E-mail reference, Bismarck, N.D.)

A: The Meadowlark forsythia can be pruned right after it is finished blooming. I suggest cutting out the largest two or three canes, right back to the base of the plant. This will get to be a large, spreading shrub 6 to 7 feet tall and about 4 feet wide. Don't worry, it will fill in a pretty big space.

Q: I'm planning on moving in the next few months and am wondering if it's possible for me to dig up my peonies, pot them, and then transplant them in my new garden. From everything I've read, peonies don't like to be moved, but my peonies are so gorgeous I can't bear to part with them. (E-mail reference)

A: Assuming you live somewhere in the temperate zone of North America, and considering the time of year, I would say no. Try and work out a deal with the new homeowner (good luck!) to come back this fall after a few frosts to dig them up. Perhaps you could offer to give them a division of some of your clumps.

Q: I have a problem with worms getting into my onions and radishes and destroying them. Is there anything I can do? (Edgeley, N.D.)

A: Radish and onion maggots can be controlled a number of ways: Don’t plant either crop close together or in rows. Mix heaping teaspoonfuls of wood ashes 1 inch into the soil where the radishes and onions will be growing. Spread an agricultural barrier (Remay or fleece) over the seeded area.

Q: I have four Spring Snow crabapple trees (about 8 to 10 years old) planted in a line about 10 feet apart in a flower bed. Three of the trees have always been good with flowers and leaves. One tree (a middle tree) is not growing as vigorously, and although it blooms, it gets very few leaves in the summer. It has been doing this for about four years. What should I check for to determine why this tree is not thriving like the others? The trees are intermixed with burning bush, which is doing fine as well. (E-mail reference)

A: It sounds like it could be a canker, root rot or borer problem. My first suspicion is canker. Look for a darkening or ring around the affected branches. Cankers (dead tissue) are often caused by fungal organisms and gradually girdle the branch, killing it completely. In the meantime, the vigor of the tree declines as yours is doing. Having said that, it is unusual for a crabapple tree to be afflicted with such a disease. Another possibility is root rot. If you can, dig down around the base of the tree and see if you can find any decay. In either case, there is not much one can do. If the tree doesn't pull out of this funk this year, then I suggest replacing it ASAP to keep the disparity between the established trees and the new planting from being too great. Borers attack mostly stressed trees starting with small branches. If branch tips seem to be dying back, follow the dead parts back to see if you can find small holes in the stems. If you do, then remove it and slice into the stem around the hole. You will find galleys where the borer has fed and likely girdled the branch, killing it. They are difficult to control once they get started, and I would rather see you replace the tree than to put a lot of pesticide into the environment attempting to control them.

Q: I need to put in a new lawn. What mixes do you recommend? I have a 2-acre rural lot and plan on putting in sprinklers about 50 feet around the house. I would like a nice looking lawn but know it won’t be as nice as a smaller lot in town. Do you have a nice looking rural mix or do you recommend blue grass around the house? Also, can I harrow my lot to get about half an inch loose soil, use a spreader on the tractor and then harrow it again? Or do I need to hire someone with a grass seeder to get it deeper in the ground? (E-mail reference, Bismarck, N.D.)

A: I would suggest a "Boulevard Mix" for your property. This is a unique mixture that contains Fairway crested wheatgrass, Fults alkali grass, common Kentucky bluegrass, fine fescue, and perennial ryegrass. This specific mixture can be obtained from a local landscaper. The price should be around $2.25 per pound. You would want to sow it at about 3 to 4 pounds per 1000 square feet. This mix is an exercise in Darwinism. If you decide to water and fertilize close to the house, the Kentucky bluegrass will likely dominate. If you choose to let the rest of your property go "natural" then the crested wheatgrass and fescue will dominate. You can apply the seed after it has been cultivated, then simply drag it into the loosened soil; don't bury it. Light is need for germination to be successful.

Q: I am having a basement put under my house, and I have a lilac bush that I will have to move. What would be the best way to do this? I will be putting it back but it will take about a month to do the basement. Also, what can you do when you cut the flowers and put them in a vase to make them last more than a day? (E-mail reference)

A: Don't bet on your lilac surviving a move at this time of year, just as it is starting to leaf out and bloom. Depending on the size, if you can dig a big enough root ball so as to not disturb the roots, then it may survive. Otherwise, forget it and replant. There are commercial preparations that you can use to extend the life of flowers in a vase; otherwise, lime or lemon juice, unbuffered aspirin, clear vinegar or anything else that mildly acidifies will help. You need to still change the water every day.

Q: How much loose dirt do I need to plant new grass? If I put some weight on my drag and get the top half inch loose, is that enough? Also, do you recommend spreading fertilizer before the seed, or how long after? What kind and how much? (E-mail reference, Bismarck, N.D.)

A: About half an inch of loose soil would be plenty. I would suggest fertilizing after the seeds have sprouted and you have mowed the lawn at least three times at 2.5 to 3 inches high. You want to apply a high nitrogen fertilizer, like 28-4-6, at a rate of about 3-4 lbs per 1000 square feet. Be sure that at least a third of the N in that analysis is from WIN (Water Insoluble Nitrogen) sources to prevent burning.

Do you have a gardening or houseplant question? Write to Hortiscope, Box 5051, NDSU Extension Service, Fargo, ND 58105 or e-mail to Ron Smith at ronsmith@ndsuext.nodak.edu. Note to e-mail correspondents: please identify your location (city and state) for most accurate recommendations.

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Source: Ron Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Editor: Gary Moran, (701) 231-7865, gmoran@ndsuext.nodak.edu