Questions on: Roses
Ron Smith, Horticulturist, NDSU Extension Service
Q: I found your address on the Web. Can you tell me the probability of bringing back a wild rose bush? I found a rose bush growing in an area with very poor lighting and a lot of overgrown weeds and trees. I moved it last year to our garden. It has healthy leaves and stems, but has shown no signs of producing flowers. (Kalamazoo, Mich.)
A: Many times wild roses are so vigorous in producing vegetation that they fail to flower during the normal growing season. If they do, it is very sparse or of little notice. Because it is in your garden, it probably is in good soil that receives regular fertilizing. If you can back off on that somewhat, it may come around to producing flowers.
Q: What causes a rosebush to loose its leaves at the bottom of the bush? Is there anything that I can do to get them to grow back? (e-mail reference)
A: This is likely black spot fungus. Once the leaves have dropped, they are gone for the season. Do some pre-emptive spraying with a systemic fungicide next spring. There are many systemic fungicides on the market to select from.
Q: I have a small growth on my young hansa rose. I have a much older one that has galls, but these bumps are different. They are quite small and located on the branches. The galls are in groups. I pulled one off, which left behind a powdery substance on the branch. The growth was hollow, but, when I pinched it between my fingers, it oozed. Is it a bug of some sort? (e-mail reference)
A: There are insect galls and bacterial galls on roses. Since the gall started to ooze when you broke it open, my guess is that this is an insect gall. Bacterial infections typically ooze without pinching. As a sweeping generalization, galls typically do not cause problems other than to worry the owner needlessly. If the rose is performing to your expectations, I wouldn't worry about these galls because they naturally come and go each year.
Q: Last fall I asked your advice on cutting back my rose bush. I cut it back, covered it with leaves and bought a Styrofoam cone to cover the bush. I put a weight on the cone to anchor it against the wind. I need to know when to uncover it so the bush can get some sunshine and fresh air. As always, your valuable advice will be greatly appreciated. (Bordulac, N.D.)
A: Uncover it on a day there is sunshine and the temperature is above freezing. I wouldn't go too far with the Styrofoam cone in case the weather takes a sudden nasty turn, which will happen. Thank you for the nice compliment!
Q: I have a few red intuition roses left from Christmas. There are new sprouts coming up on the stems, so I would like to know how to graft them and start new plants. (e-mail reference)
A: Sorry, what you are asking is illegal. This is a licensed, patented plant cultivar that is protected from propagation.
Q: I called you a few weeks ago to ask about a florist rose that had leaf sprouts on the stem. You said to make cuts, put rooting hormone at the end and stick them in damp sand. I have some chicken grit and perlite. Can I use one of those instead? Also, is now an OK time to trim some lilac branches or is early spring better? (Dickinson, N.D.)
A: Chicken grit or perlite will work, but you need to have well-aerated and moist support. Lilacs should be pruned in the spring right after blooming.
Q: We have a hedge of dogwoods that are overgrown, so we need to prune them to the ground. Can we do it this fall or should we wait until spring? Also, I need to move some rhubarb. Can I do that this fall or is it advisable to wait until spring? What kind of soil amendments should we use? I have a morden sunset rose that had a bad case of black spot this summer and now has very few leaves. Can I cut all the canes down to about 6 inches and clean up all the mulch and leaves or is it a lost cause? (Cooperstown, N.D.)
A: You can cut the hedge back in late fall or early spring, but before new growth begins. Fall usually is preferred because the working conditions are better. The same holds true for rhubarb. Always add sphagnum peat moss because it will never hurt and always helps. For your rose, do the cleanup and next year use a systemic fungicide to control black spot.
Q: I put in a row of simplicity roses last year. I covered the root area with flax straw just before freeze-up and uncovered the plants in the spring. I mulched with bark. Do I need to use the flax straw again or would they be fine just using mulch? This fall I've noticed black spots on the leaves and some light gray to white discoloration. I thought the problem might be black spot and mildew, so I cut away the affected leaves and stems and burned it. Then I sprayed with Daconil. I see by your column that I should not have sprinkled it right on the plants. Someone told me that roses need lots of water and it's good to keep the plants and soil damp, but water early in the day. (Munich, N.D.)
A: If you want to practice "safe gardening," I would suggest mulching with straw every year. Why take chances? Keep the roots moist, but not the foliage. There are systemic fungicides out there that will keep the plant protected through the growing season.
Q: I purchased a rosebush last year. It bloomed, but only had a few flowers. Should I prune the bush every year? If so, how do I prune it? What can I do to get the bush to grow more roses? Also, I have a flower garden in the front yard, but the flowers didn’t grow. My husband placed peat moss in the garden, watered on days it didn’t rain and used Miracle-Gro once a month. (e-mail reference)
A: Hybrid tea, multiflora and grandiflora roses produce flowers on new growth. The general recommendation is to prune the rosebush back in the fall, if winter temperatures are relatively mild, such as temperatures rarely falling below zero. In colder climates, prune in the spring while the plants are dormant. In both cases, the roses should be mulched before the onset of winter weather. If your husband merely "placed" peat moss in the garden and did not till it in, the treatment will be of little use. Annually tilling in sphagnum peat moss is one of the best universal treatments for any flower or vegetable garden.
Q: I have a sample of a Hanson hedge rose that appears to have cankerworms on the leaves. It's green in color with a dark head. It does not loop as a normal cankerworm does. There also is a large, brown gall along the side of the rose. The gall appears to be attached to a stem. Also, what are the miniature flies called that I've seen on this and other indoor plants? (e-mail reference)
A: There are two types of galls that typically form on rose bushes. One is a wasp gall and the other is a bacterium gall. The difference is fairly easy to tell. The wasp gall is thin-skinned, while the bacterium has a corky growth. Both galls can be removed or left alone. The plant will survive with them in most cases. The larvae could be a species of sawfly, which is easily controlled by spraying with Orthene or another insecticide. The miniature flies are fungus gnats or fruit flies. They are controlled by using a knock-down insecticide spray.
Q: I have a wild rose bush that is getting out of control in both width and height (12 or so feet high). How and when should I cut it back? Can I take my chainsaw and lop the whole thing down each spring or fall? Can I safely dig out some of the base of the plant? If so, could I possibly even replant the portions I dig out? (e-mail reference)
A: Go ahead and do some cutting on this monster. I promise it won't hurt anything. Every spring, cut it to the size you want and then some. Take into consideration the surge of new growth that will follow. Always cut just above a leaf or lateral branch.
Q: I have two rose bushes, a Morden centennial and a William Baffin. They are hardy and winter well. During the growing season, the roses are plagued by insects and fungus. They bloom in the spring, but then disease takes over. I have used Bayer Advanced Garden Rose, Flower Insect Killer and Garden Safe Fungicide. The leaves are just beginning to come out. Is there anything I can do with the pests and fungus to stay ahead of the game? Maybe I didn't start early enough last year. I have used Miracle-Gro rose food about every two weeks as directed. The fungus produces black spots on the leaves that then turn yellow and drop off. The county agent said the insects were alfalfa bugs. (Jamestown, N.D.)
A: It should do the job if you stay ahead of the arrival of insects or pests and apply protective sprays every 10 to 14 days.
Q: I have six hybrid roses that I planted along the fence of my front yard. I tried to use a plant screen to keep the grass down, but it got infested with ants, so I took it out and mulched it. Now the grass is really growing around the roses. I need a suggestion as to what will kill the grass, but not hurt the roses. (e-mail reference)
A: Visit a local garden center and look for a product called "Grass Killer" put out by the Hi-Yield company. The active ingredient is sethoxydim, so if the company name is not easily found, look on the label of other grass killers to see if the active ingredient is the same. Follow the directions on the label and you will get selective control of the grass without hurting your roses.
Q: I received a minirosebush this Christmas that was full of blossoms. All the blooms have fallen off and are not growing. Do roses only bear blooms at a certain time of year? When should I plant it outside? (e-mail reference)
A: The rose will flower again when it has enough energy. You can plant it outside when the danger of a killing frost is past.
Q: I need your advice on what fertilizers I should use for my rose and lilac bushes. I planted them in July. I am going to mulch them before winter sets in and I wasn't sure if I should give them some food before I put the mulch down. (e-mail reference)
A: There is nothing needed, so go ahead and mulch. When they begin growing next spring, fertilize the bushes with any commercially available product that is labeled for flowering shrubs.
Q: I have decided that I need to move my morden blush rose because it doesn’t get enough sun in its present location. Do you have any suggestions about transplanting roses? (e-mail reference)
A: Allow it to go dormant this fall, cut it back hard, and dig it out and move it to the new location. Replant at the same depth. Water it well and mulch just before freeze-up.
Q: This year I was looking forward to the blooms that I thought would come out on my Madame hardy rosebush. The buds were plentiful, but they wilted, went yellow and fell off. Please help. (e-mail reference)
A: Look for cane borer, thrips or cane girdler damage. If the rest of the plant is healthy, it has to be an insect-caused problem.
Q: I have a fairy rose that appears healthy and produces many buds, but will not produce flowers. What do you think is the problem? (e-mail reference)
A: It could be thrips or aphids feeding at the base of the buds or within the fold of the buds that keep the flowers from opening. Check the flowers closely. I’ll bet you will find evidence of one or the other.
Q: I have had a lot of landscaping done by a local nursery. The yellow carpet roses that were put in 10 days ago looked beautiful, but now all the interior leaves are yellow with black spots. The roses receive partial sun. What can I do? (e-mail reference)
A: The local nursery should have known better than to plant them in a partial sun location. Get them moved to a full sun location and stop watering from overhead. Overhead watering sets the stage for black spot fungus to move in and defoliate the plant. In the meantime, spray the roses with a fungicide, such as Funginex or a rose specific fungicide that will control black spot.
Q: I am trying to find out how to extract seeds from rose hips. (e-mail reference)
A: It’s a piece of cake. Allow the hips to mature on the plant, cut them off and when dry, simply cut or break them open to extract the seeds.
Q: I have a rosebush I had to relocate and now some of the leaves have a yellow line on them. Could you please tell me what to do? The bush has blooms on it and everything else looks OK. (e-mail reference)
A: Those lines could be the result of damage to the root system, which could be limiting the uptake of nutrients. Apply a fertilizer, such as Miracle-Gro, once a month during the growing season to help get the plant established.
Q: In a store, I found one of the most perfect and beautiful roses I have ever seen. I have been trying to find where I can purchase the bush. The name of the rose is red intuition. The House of Del Bard bred it in 1999 in France. It is a descendent of the red painter rose. (e-mail reference)
A: This is a florist rose and may not be available to the gardening public. It can be grown anywhere from Oregon to South America or even in Holland greenhouses! While it may be a majestic, drop-dead beauty in an arrangement, as a garden rose bush under typical conditions, it may be a loser. I don’t know. I would suggest attempting to contact the Society of American Florists or the American Rose Society to see if they can lead you anywhere. They should be able to give you a definite answer.
Q: I have heard there are certain types of plants that like to grow with rose bushes and actually help them grow better. Any ideas? (e-mail reference)
A: Yes, supposedly there are. What you are referring to is companion planting. This is the principle that one species of plant will attract either beneficial insects that will aid in controlling plant-destructive ones or will provide a scent so that the destructive insect cannot locate the crop to be preyed upon. I would suggest reading “Roses Love Garlic” by Louise Riotte. It is a very interesting and educational read. The book contains useful information for any serious gardeners who are looking to reduce pesticide use in their garden.
Q: I was just on your Web site to find out if I could start a rose bush from a clipping. You said that it was easy, but you didn’t say how. Is there a certain area on the rose where I should take the clipping? The bush I want to take a clip from has been doing well for years. I’m new at trying my hand at starting new roses, so any help is a big plus. (e-mail reference)
A: It’s a piece of cake. Take cuttings from wood that is not in flower. The cuttings should be at least 6 inches long. Stick the cuttings in a sand/peat mix (50/50) that you can keep moist. The cuttings should be kept away from direct sunlight. Mist several times a day to keep the cuttings hydrated. They should set roots in six weeks or less. If the cuttings wilt, then wait until the plants go dormant this fall and then take the cuttings sometime before they leaf out the following spring. Rooting hormone powder will help push things along. To learn more about plant propagation, go to my Web site at
www.ext.nodak.edu/extpubs/plantsci/landscap/h1257w.htm. You will find all kinds of information on the Web site about starting plants from cuttings, grafting, budding, seed and tissue culture.
Q: I bought a house with yellow roses behind the house. I want to keep them, but they are spreading like wildfire all over the yard. How can I stop the roses from spreading? (e-mail reference)
A: A physical barrier inserted into the soil is probably your best bet. A plastic barrier can be purchased that goes down about 6 inches. In some cases, Ryerson steel edging is used. The plants are beautiful, but also invasive!
Q: I had someone call this morning who has miniature roses, begonias and hibiscus in pots. She has moved them into her house. How does she care for these plants so that they make it through the winter? Does she need to prune the plants or do something else? If these plants are normally dormant during the winter, does there need to be some “neglect” to allow dormancy? (Carson, N.D.)
A: All three plants, the miniature roses, hibiscus and begonias, can make it as houseplants. Generally, the roses will need to go through a little dormancy/chilling period, so if they have not been treated to the fall weather, allow them to stay outside for a few more nips by Jack Frost and they should be in sufficient dormancy. As to the hibiscus, she can cut it back somewhat to set it up for some new growth. Place the rose and hibiscus in as sunny a location as possible in the house. The begonia will do OK under a plant light and probably will flower sometime during the winter.
Q: I have a man looking for information on starting roses from seed. If you have any suggestions regarding what information I should pass along to him, I would really appreciate it. (e-mail reference)
A: The seeds need to be extracted from the hips (fruit). To break the tough seed coat, stratify the seeds in moist sand at 80 to 90 degrees for about three weeks. I would then suggest storing them in an airtight jar. Place the jar in a cool and dark location until spring. Sow them in a sunny location when the frost is out of the soil.
Q: I have a client who is wondering about the possibility of propagating hybrid roses. Is this possible? Do you need a root starter? Should you put the clippings in water or directly into soil to root? If this works, how long would it take until a new rose plant would be ready to plant in the garden? (Cando, N.D.)
A: Hybrid roses are usually protected by a patent number. If this is the case, then any propagation would be considered illegal. If they are not protected or the patent has run out, then stem cuttings are the easiest way to go. Semi-hardwood cuttings root easily in a sand/peat mixture. There is a downside to using this method. The rootstock may lose hardiness, dwarfness or disease resistance.
Q: Can I move a rose bush at this time of year? If not, when is the best time? (LaMoure, N.D.)
A: A rose, or any plant, can be moved whenever needed, but the best time is in the spring followed by early fall.
Q: A producer planted a rose bush some years ago. The first two years it blossomed profusely. In the last two years, the buds have only opened partway. (Beach, N.D.)
A: It could be thrip activity. Look closely at the buds and peel the outer petals back to see if there is any evidence of feeding activity or the dirty bounders themselves. If not, then cut the stem off and check for borer activity. The stem should be hollow and empty, or if you are lucky, hollow with the culprit caught in the act! You know what to do then.
Q: My roses have orange stuff all over them. We have had them for 32 years, but this is the first year this has happened. I figure it is a fungus, but would like to know what to do about it. (e-mail reference)
A: You are right; it is a rust fungus. At the first sign of this malady, pick off and destroy the affected leaves. If it is too late for that, spray with a fungicide appropriate for rust on roses such as lime/sulfur or one of the many other products on the market. Repeat the treatment according to label directions, which is generally every 10-14 days or when new growth emerges. In the fall, pick up all fallen leaves and prune back as you normally would. Next spring, prior to new growth, spray again with lime-sulfur. Hopefully the wind and moisture sources will be in your favor.
Q: I have a question that I'm sure you'll find easy to answer. I found some galls on a bunch of rose bushes. They have tiny holes in them, which I assume are insect holes. I hope removing them was the right thing to do. (Bowman, N.D.)
A: You are correct! This is a gall caused by the larval stage of a small wasp. Removing them was the right thing to do. Galls act as a nutrient sink and can pull sufficient levels of nutrients away from the plant to cause deficiency problems. There are no insecticides that can control them, so removing them is the only solution.
Q: My son got me three miniature rose plants for Mother's Day. They had several blooms on each of them that have since turned dark and died. Do I cut the dead roses off? How far down do I cut? I am going to repot them as they are in very small pots. (e-mail reference)
A: Cut the dead blooms off back to just above a leaf attachment. Repot, water and fertilize. You should get more blooms in a few weeks.
Q: I have a yellow tame rose that has lots of dead branches in it. Can it be cut down to the ground this fall or should I just cut out the dead parts? How can I start new bushes from the old? There are lots of sprouts coming up around it. (Redfield, S.D.)
A: Cut it back to the green wood to clean it up. This fall, cut the branches back to about 12 inches and cover with soil and leaves. Those sprouts are from the roots, not the scion or budwood. Take green cuttings this summer or collect the fruits if any form after the flowers are faded and allow them to dry. Remove the seed and see what happens when you sow them.
Q: I have a
yellow rose bush that has always produced beautiful yellow roses.
This year it is beginning to bloom but the buds are all scarlet
red! What in the world is going on? I have not touched this bush
since last fall when I pruned it. Any explanation?
A: Unless the new growth is coming from below the graft union, I have no explanation. Sometimes the buds are a different color than the open flower. Sorry I cannot help you more!
Q: My rose bushes bud, but only a few bloom. They then turn brown and never fully open up. (E-mail reference)
A: It sounds like a very common disease known as botrytis. Try spraying them with a systemic fungicide this spring as new growth begins.
Q: A friend of mine has a rose bush that I’d like to take a cutting from. Where should I cut the bush and what do I need to do to plant it? (Email reference)
A: Cut a piece about six to nine inches long from just below a leaf node, which is where the leaf is attached to the stem. Remove the leaf and make a slanted cut just below the node. Place the cutting in a sand/peat mix (50/50) and keep it moist. The cutting should be kept in the shade to prevent wilting. If you are lucky, in about six weeks, roots should form. You can plant it in a protected location for the remainder of the summer after the roots get to about four inches or so in length. The following spring, while still dormant, you should be able to move it to a permanent location, assuming it survived the winter.
Q: I planted 25 rose bushes and half seem to be wilting. I put fertilizer in the holes before I planted and sprinkled some on the ground. Someone told me the roots were burning and I need to put a soaker hose on them to try and wash out the fertilizer. The plants do perk up after they are watered for an hour or two. Would it hurt to put a soaker hose on them to flush the fertilizer or is there another problem? (E-mail reference)
A: You are doing the correct thing by attempting to leach the fertilizer salts out of the root zone. I suggest spraying the foliage with an anti desiccant to keep them from transpiring water through their leaves, which should keep them from wilting. Some of the wilting is probably due to the tenderness of some new growth. Once the plants have adapted to their new environment, in a week or two, the wilting should stop. Just be sure to keep the water off the foliage.
Q: Are you supposed to wait until the ground freezes before you mound roses with dirt? It is hard to find dirt that is not frozen if you wait that long. (E-mail reference)
A: I suggest getting potting soil that has been sterilized or pasteurized to place over your roses. That way you don't have to worry about trying to move any frozen soil. The clean soil will be free of pathogens that might get started if you are not gung ho enough about removing it in time next spring.
Q: We have three rose bushes that are doing well. Should they be cut down this fall or wait until spring? (Powers Lake, N.D.)
A: Cut them down now and cover generously with soil and leaves for winter protection.
Q: I have a rose plant that for the past few years has not bloomed. I don't know its past history because I have only lived here the past two summers. The growth is very prolific but I have yet to have a single blossom. I have several other rose plants that are doing fine. Would you happen to know what the problem might be and how I can correct it? (E-mail reference)
A: From your description, it is probably growing from the rootstock only, so it will not produce a flower. I suggest digging it up and replacing it with a fresh plant.
Q: I have a couple of rose plants that I need to transplant. When is the best time of year to move them? I have a spot in front of my house (south side) that had black plastic put down. On top they have a red rock that I think is scoria. The plastic is real old and is tearing and decomposing. I have a lot of weeds. I would like to cement some of it and then redo the flowerbed. Would you recommend putting plastic down again and then the decorative rocks or just use soil? I do not like to do a lot of weeding. I think I already hurt two of the other roses. I trimmed the branches so now they grow tall but do not produce roses. (Bismarck, N.D.)
A: Spring transplanting is best while they are still dormant. If you are a gambler, you can do it in the fall but I wouldn't do it in our climate. Forget the plastic and rock, use Preen instead and cover with organic mulch. The roses will be a lot happier and so will you!
Q: My husband and I would like to plant roses but I've heard they’re hard to grow. Could you advise me on a hardy rose bush that might do better in our cold Minnesota weather? Do you know where I might find them? When can they be planted? (Crookston, Minn.)
A: I would suggest selecting the prairie (Rosa setigera) or prairie wild (Rosa arkansana) rose as your initial selections if you are a beginning rose gardener. They are native and hardy for the northern climates. If you are not familiar with these roses, they are not at all like the standard roses you may have seen in other parts of the country. The prairie wild rose is a suckering type, cold and drought hardy, and gets about 12 inches tall. Some consider them a weed. The prairie rose can be used as a climber or a bush. It produces single pink flowers in July and attractive rose hips (fruits) in the fall, which help to attract birds to the landscape. Neither of these roses needs special winter protection. The others require extensive protection depending on your location. Your location may require you to use the "Minnesota tip" which means the entire plant is tipped over into a trench and covered with soil before winter. All roses require good sunlight, air movement and decent soil drainage to be at their best. I would suggest visiting a local garden center in your community to see what the local proprietors have to offer.
Q: I would like to know what the difference is between a red rose and a black rose on valentines day? (E-mail reference)
A: Very important question. Red roses bespeak of one's deep and passionate love for the receiver. A black rose doesn't exist in nature and is in fact the holy grail of plant breeders worldwide. They come close with very dark red roses that appear close to the mystical or wished – for color. With this dark color comes the mystical expectation that something wonderful, such as a marriage proposal, will happen in the near future - a few minutes, hours, or days. There are a couple of roses that florists may carry that have the deep, dark velvety hue toward black that you can use. Black magic, black baccara and black beauty are some examples that may be available. My advice? If your intent is to become engaged, then go for one of the black varieties intermixed with some pure reds. That will show your passionate love and intentions. Good luck!
Q: Can you tell me how to cross-pollinate roses or any other flower? (E-mail reference)
A: I am hoping that you know the various floral parts as I describe them. If not, then I suggest you get a basic botany text from your local library. The rose flower has both sexual parts. The stamen (male) has the anther or pollen bearing structure. The pistil (female) is made up of the stigma, style and ovary. You have to figure out which flower is going to be the donor (male) and which one is going to be the receptor (female). Once that decision has been made, emasculate the receptor flower of all pollen-bearing anthers as soon as it opens. Do it carefully so as to not damage the female organ. Then take the donor flower and make sure the pollen is mature. It should leave a little dust on your finger or brush. If it is mature, then take a small lettering paint brush and gently rub it over the pollen bearing anther on the donor flower and transfer that pollen to the stigma on the female part of the receptor flower. Do this until the stigma will no longer take any pollen (it will start to dry up). If you are working with a rose, the petals should then fall off and the rose fruit (called hips) should develop slowly. As the fruit matures it turns a bright red. At that point it is mature. You can then harvest the fruit (hip) and allow it to dry. Once dry, gently crush it and carefully separate out the small seeds from the litter. Sow under proper conditions and see what you have produced with your cross-pollination! If you are doing this outside, you’ll want to cover the fertilized flower with a sack to keep insects from messing up your careful cross-pollination. That step won’t be necessary if you are doing it in a greenhouse.
Q: I planted 12 rose bushes on the south side of my house last year. They have bloomed beautifully all summer. Can I cut them back and how much? Will they bloom next year if I cut them? (Mercer, N.D.)
A: Prune the roses back to about 9-12 inch canes after a couple of hard frosts this fall. Then just before freeze-up, take soil from another location and cover the canes completely with 8-10 inches of soil. Add to that a bag or two of leaves you raked up from your yard and you should have them over-winter for you.
Q: I would like to know if it is possible to start a rose bush by taking part of a branch off of another rose bush? (Menno, S.D.)
A: It can be done, quite easily in fact, but the hardiness imparted by the grafted stock will be lost. So be sure to provide the plant with ample winter protection.
Q: I have lots of questions, in fact 37 cents worth! I read and enjoy, save and use much of your column. First, my delphiniums seem to rot from the bottom up. I've treated with Gardengard which is for bugs, snails and slugs. Could it be silver fish? Two new plants did the same in a new spot. Could this have come from the greenhouse? Should I reset them in an entirely new place? Second, I have lilies but something is boring into the stems so they get dry and brown and break off. I've treated with Gardengard which may have helped some. I remove and burn the affected stems. Any suggestions will be appreciated. Third, how can I start old fashioned roses from cuttings? I'd hoped not to have to dig up starts. I tried rooting compound and potting soil, but the twigs just dried up. Fourth, is there any hope for baby evergreens once they lose their needles? Might they come back in the spring if I continue to water and care for them? (Bristol, S.D.)
A: Here are your answers - thanks for writing and the nice comments about the column.
- Definitely relocate the delphiniums. I don't know what the problem is, but whatever it is, don't go back. Make sure they get direct sun.
- Try a systemic like Orthene.
- I’ve enclosed a "Home Propagation Techniques" publication available from our office.
- No hope - they're history.
Q: A lady called in with a rose bush that is 10 to 12 years old and about 6 feet tall and 6 feet wide that has a bright orange looking fungus or mold. She says she has seen it one other time but not very much. The ground is sandy where she is but has had quite a bit of rain. Any ideas on what could be wrong and how to treat it? (Cavalier, N.D.)
A: What you are seeing is a stage of the cedar-apple rust. Apples and roses are in the same family and are subject to this same fungus. All that needs to be done is interrupt the life cycle by removing the infected leaf or leaves. There are several protective fungicides that can be applied as well.
Q: I planted a shrub rose ("Morden Blush") this spring and it has flowered nicely, but the canes are so weak they can't hold the flowers up. The same thing happened last year with another variety. Is the soil lacking something? Or do you know what I can do? I have several shrub roses (all about 2 years old) and all of them do not do this. (Vergas, Minn.)
A: They might not be getting enough sun, but if they are flowering, you've got it made. Put some tomato or peony cages around them for support for now.
Q: We have a yellow tea rose bush on the east side of our home. It is beautiful and loaded with blossoms. It is about 4 feet high. There are many runners coming out that are also blooming. Can they be dug up, and will they grow and blossom? If so, what time of year would be the best to dig up and plant? (Cooperstown, N.D.)
A: Very likely the sprouts you are seeing are from a vigorous root stock that is different from the rose flower you are appreciating. They will certainly grow on for you, but I’d suggest waiting until next spring to do the digging -- get them before they leaf out.
Q: I transplanted a hybrid tea rose (Perfume Delight) in the spring of 2000 before it came out of dormancy. The following season it had good growth and foliage but no flowers. I continued to fertilize and give general care as usual. In 2001 it continued good growth and foliage but only had one bud. When it opened it was a small, magenta colored flower. In 2002, again it looks good and now has many buds but the flowers are small, magenta colored, and no fragrance. It is almost as if the hybrid tea has turned into a shrub rose. Before I moved it it had big, pink, and very scented flowers. What happened? (Onida, S.D.)
A: The only thing I can guess is that the scion or budwood, killed off when you moved it, and what you are seeing now is the growth coming from the rootstock, which, of course, is a rose, but not the hybrid tea that you wanted.
Q: What is the difference between roses advertised as miniature roses and those that say fairy roses, which are apparently similar in size. Jackson Perkins says "Fairy Roses" will winter in North Dakota with protection of some sort. I'm not sure about the miniature roses. Any thoughts? (E-mail reference)
A: I am not familiar with the Fairy Roses. If J&P claims they will winter in North Dakota with some protection, I'd make sure they got plenty! If they are not too expensive, give them a try if they appeal to you.
Q: My mother has a red rose bush planted next to her house. It has been there for many years. Until recently it always bloomed beautifully, but now it does not bloom at all. It hasn't bloomed for two years now. It has great plant growth but never puts on any flowers or buds. Other than digging it up and replacing it with another rose bush, is there anything we can do to make it bloom again? I can not tell you what kind of rose this one is, as it has been there for many years and no one can remember what kind it is, other than red. She always trims the bushes in the spring. As soon as regrowth starts, last years growth is trimmed off. She has several other rose bushes as well in the same area, and they all bloom great, and are all about the same age. (Reliance, S.D.)
A: What has happened is the scion (aka "budwood") has died off and the root stock is suckering new growth, which for the most part is flowerless. It has vigorous growth, but no flowers. The only thing you can do is replace it.
Q: Have you ever seen the Christmas rose (helleborus niger buis) growing in this area? I planted one last year and it didn't survive. It is supposed to be hardy in zone 3. What kind of soil do they prefer? (E-mail reference)
A: Actually, hardy to zone 4, but this past winter shouldn't have killed it. They don't like hot soil. The prefer cool, moist, and high in organic content soil that is also well-drained. Kind of a hard combination to come up with in the Red River Valley soil!
Q: I received a miniature rose bush for Valentine's Day. It came in a ceramic container. I was wondering if I could keep it the container and how to take care of it. (E-mail reference)
A: The track record for miniature roses is generally not too hot. I have no clue as to where you live from your e-mail, but if you live in a relatively warm part of the world where frosts are light and infrequent during winter, then get it outdoors ASAP. If you live in the north where winter weather is severe, you are better off bringing the plant indoors to overwinter, placing it in a sunny window with supplemental lighting. My experience with miniature roses has been that they are subject to powdery mildew and black spot and host to a variety of insects beyond what normal garden roses are. They need plenty of light -- direct sun if possible. If the ceramic container is not free-draining, then move it to another one that is; prune spent blossoms; fertilize with a rose fertilizer every two to three weeks during active growth. Enjoy the gift for as long as you can. You might want to select a flower that is partially open and press it between the pages of a book with a note memorializing who it came from. That will likely last longer than your plant will if history is any guide.
Q: I have a rose bush that is getting too large. How far can I trim it down and not kill it? Also, when should I cut off my peonies and iris? Should I do it now? (Valley City, N.D.)
A: You can trim the rose bush down to 12 to 16 inches or so. While you can cut the iris and peonies off any time now, I always believe it is best to wait until after a frost.
Q: Can you tell me what is wrong with the enclosed rose bush and strawberry leaves? The strawberry leaves are from a new patch that started out good, but during the summer some of the plants started turning yellow. Is this a condition of the soil or disease? What can I do to remedy it? (Bowdon, N.D.)
A: Both plants are showing an extremely bad case of iron chlorosis, most likely induced by high soil pH. There is a good chance this can be corrected with the application of chelated iron on a regular basis. I suggest making the initial application just before new growth emerges next spring. After that, monthly applications should keep the problem from showing up again.
Q: I am wondering if you can give me any information about North Dakota wild prairie roses. I am especially wondering if they can be transplanted from the roadside to a more conventional type of garden. I am very fond of them but have had little success when I have attempted to transplant them and wondered if perhaps you could shed some light on the subject. ( Wishek, N.D.)
A: Your lack of success is likely tied with your timing in moving them. I suggest picking out the ones you want to move a full growing season ahead, tag them, root prune them, then dig them the following spring while they are still dormant, pruning them back by about one-third before doing so. Set them at the same depth, water and fertilize, and you should be successful.
Q: A year ago I planted two rose bushes. I pruned the roots some and placed the rose roots in the ground. The roots are growing, but it’s just one long stem over 8 feet high. Will it get to be more bush-like and flower? Will it end up looking like the "silent moment" roses that I originally planted? (Park River, N.D.)
A: You’re growing a rose bush from the root of a different species than the one you bought. Roses are grafted on to rootstock to impart vigor to the scion or budwood. Your testimony about its rate of growth is proof of that vigor. The flower will (if it comes at all) not look like the "silent moment" rose. I suggest digging out this rootstock and disposing of it. If you want to try to grow this rose, take cuttings from the stem.
Q: I have three rose bushes that have grown back from last year. None have any buds on them as of yet. The plants all look very healthy. Someone told me that if a rose grows back from below the base of the plant, it won’t blossom. Is this true? That seems to be the case with these roses. Will they ever blossom or should I just dig them up? (Williston, N.D.)
A: Oh, the problem with partial truisms! The growth from below the base of the plant is from the rootstock, which is used to impart vigor to the scion or budwood. When this dies, the scion "dominance" is removed from the roots, which then produce sucker growth that is extremely vigorous, and generally non-blooming. However, if the rootstock sprouts were allowed to remain, they would eventually bloom, but not with the same flowers of the original plant. Certainly less attractive. In essence, just dig them up!
Q: What's the best herbicide to kill out volunteer roses? A yard owner wants to take them out and replant to something else ( not sure what). Will Roundup do the job? How much growth does she need to get a good kill with it? Will Curtail or Stinger do them in without too much herbicide persistence? Is there a cultural practice that will work better than herbicide? (E-mail reference, Fort Yates, N.D.)
A: Roundup should do the job. Let the new growth mature fully, then give them a shot. I cannot answer your question on the other two herbicides as I don't know what the replanting intent is. I know of no cultural practice that will get rid of them better than Roundup.
Q: Will you please address the following questions:
No.1: We have put an apricot tree in our back yard. Is it necessary to have a second apricot tree of the opposite sex for it to bear fruit? We have a chokecherry, Juneberry, Nanking cherry, plum and pear tree nearby. Can any of these cross pollinate with the apricot?
No. 2: How do we properly prune our shrub roses? Even our veteran rose people in the Bismarck-Mandan Garden Club don't seem to know the answer to this one. (Bismarck, N.D., e-mail)
A: To answer your questions:
No. 1: You have a good selection of Prunus species for the pollination to take place. It sounds like you should be getting a lot of fruit off the trees and shrubs you have planted. Enjoy!
No. 2: Shrub roses need little pruning in comparison to their hybrid and floribunda cousins. Simply remove the winter killed wood and clean up any tangled, nonblooming growth at the ground from the centers of the older bushes. Be sure you wear HEAVY gloves and that you use your best, sharp pruners! That old wood can get to be pretty tough at times, and those thorns seem capable of penetrating anything short of armor plating. If it proves to be too much of a blood-letting task, then simply cut them back to the ground and allow them to regrow.
Unlike the hybrid teas and floribundas, don't head these back once they have finished flowering. The objective in pruning shrub roses is to promote their natural form whether it be upright, spreading or drooping. Once the flowers have finished, attractive fruits called "hips" form that add to the beauty of the plant.
Q: I have several questions that came up this growing season:
1. Our new house came with three overgrown and neglected crabapple trees, the pruning of which triggered what appears to be fireblight. I optimistically and lovingly planted and pampered an expensive new rosebush, not realizing until later that roses are related to apples. It turned brown and died within several weeks. Is there any way to grow healthy roses in our yard?
2. We collect rainwater from the roof and use it for houseplants as well as the garden. Could the blight bacteria be in the rainwater? My kitchen herbs are blackening, and the impatiens outdoors are also showing brown leaves.
3. We replaced all the house's old leaky windows with new ones having what they called "low-E" glass. They're wonderful for keeping the winter warm and the summer cool, but I wonder if they block too much of what our houseplants need of sunlight. They seem to get pale and leggy even in the sunniest windows. (Palermo, N.D.)
A: You ask some very good questions!
1. The fireblight bacterium is airborne and therefore present in rainwater. Being a bacterium, it can enter microscopic openings, which plants are full of. Concerning your rose passion, try it again only this time plant in another location, avoid water splashing on the foliage, if possible, and keep it sprayed with a multipurpose fungicide spray or a fungicide containing triforine. Lime-sulfur and Daconil 2787 are two other examples of the many fungicides available for roses.
2. Has your roof been re-shingled in recent years? Could be some chemical toxins coming off that. The fireblight bacterium doesn't infect all plant material, of course. You could also be getting Pythicum fungus started on your plants.
3. You bet! I don't know the range of light that is being blocked, but it has to be within the range that helps produce chlorophyll. There are "spot plant lights" which you can use to overcome this.
Q: Is there any way to keep the flowers on my Annabell hydrangeas white longer? And can you tell me why my wild rose is not blooming? (Moorhead, Minn.)
A: As far as I know, there is no way to extend the white color of the Annabell hydrangea, and the wild rose is probably living too good a life. Don't fertilize or water it, and drive a straight-edge spade in the ground in three places around the plant. This severs some roots and may cause it to flower. If none of these work, yank it out!
Q. I received a miniature rose bush for Mother's Day, and I am wondering if I can plant it in the ground. Should it be in full sun and when is the best time to transplant it? I also would like to know the names of some self-seeding annuals. (LaMoure, N.D.)
A. Roses like full sun early in the day, as it helps to keep black spot and other leaf diseases under control. Plant it after it goes dormant this fall. Be sure to give it plenty of winter protection.
Now, for some self-seeders--my favorite kind of flowers:
- Nigella, or love in a mist. Nice feathery foliage, bluish, lacy flowers. Seed pod dries beautifully.
- Nicotinia sylvestris, or giant flowering tobacco. Nice fragrance. Be sure to plant in back of the garden.
- Verbena bonariensis--small purple flowers will show up everywhere.
- Cleome, or spider flower. A good tough one to withstand our prairie winds. A nice range of colors and tall--3.5 to 4 feet--but not as tall as the flowering tobacco.
- Others include poppies, columbine, borage and forget-me-nots.
Q. I planted two bleeding hearts and they are steadily disappearing on me. What is wrong with them? The leaves on my geranium look tight and curled, what is the problem? Some of my tulips came up this spring, got a large white leaf, and did not develop a flower. Why? Should a perennial flower garden have something done to the soil to give plants an extra boost? Also, what is wrong with my rose bush--the leaves are slightly brown? (Munich, N.D.)
A. It is the natural character of the bleeding heart to die down after flowering in the spring-- nothing to worry about. They will reappear next spring.
Your geranium has a couple of maladies. One you already named, crinkle virus, and another--a heavy infection of sooty fungus.
Do you have a bunny population? They love my tulips! It could also be that some did not have a sufficient cold treatment or were too immature to produce a flower this year. I suggest patience!
As for your perennial garden, work in quality compost or sphagnum peat moss in the upper 6 to 9 inches before planting. Mulch with the same.
The roses have something wrong in the root system--too much fertilizer, water or whatever.
Q. I just planted three hardy, shrub-type roses. They were purchased from a nursery, potted, and already in bloom. Should I fertilize them? Or is it too late in the year? I'm watering like crazy, because it is so hot now. Any other tips for these late-planted roses? (Bismarck, N.D., e-mail)
A. Yes, new roses should be fertilized now. That will help to get them established, and no matter how carefully they are handled at planting time, expect some set-back. I'd give them a shot of Miracle-Gro now, in early August, and then call it quits for the year. Watch water splash on the foliage, so that you don't encourage the development of black spot fungus!
Q. I have yellow rose bushes that have been growing in the same spot for 30-plus years. I do not know the name of the bushes, but they bloom only a couple of weeks in late May or early June. I want to move them to another location, so I am wondering when the best time is to do this? I also need to know how to get the weeds out of the bushes when I move them. I also have an upright arborvitae bush (I think that is what kind of evergreen it is), and I am wondering if it is safe to cut off the branches that have been bent over by wet snows. (New Salem, N.D., e-mail)
A. Dig and transplant your roses as soon as possible, before new growth breaks. Cut them back heavily, anywhere from one-third to one-half their original length. Make clean cuts with pruners on the root systems when you dig out the bushes. Roses like to be pampered! Move them into soil that has been well prepared with compost and they will thrive much better for you than if you made no soil prep at all. As far as weed removal goes, I'm afraid the only way is the old fashioned way—removal by hand as you are digging them. You might want to work in a rose fertilizer like 10-10-10, or simply water them in with a Miracle-Gro solution.
Rather than cutting your evergreen branches off, try tying them up to a stake or broom handle with some rag cloth for about three to four weeks to see if that gets them straight again--it usually does. If you have no choice but to cut them back, do so this spring, and try to shape them up to your desire later.
Q. I live in Crosby, N.D., and I have three Adeliene Hoodless rose bushes. I planted these roses five years ago. They used to be covered in flowers from early June until late August. The last two years, they have only about half the flowers and are done flowering in late July. They then send up 3- to 4- foot shoots which have no flowers on them. I have been using a Miracle-Gro fertilizer which is supposed to be formulated just for roses. I would appreciate any advice you could give me to return these roses to their former flowering vigor. (Crosby, N.D.)
A. The rose scion, or bud-wood, is slowly dying and the rootstock is sending up sucker growth from the root system. I suggest cutting the sucker growth back completely whenever it appears and continuing to fertilize as you have been in the past. Make sure the roses are not shaded from adjacent plant material which may have grown quite a bit over the past couple of years. Other than the possibility of insect or disease problems, I cannot think of any reasons why they should be declining.
Q. Can you tell me why I have trouble growing bush-like roses such as Potentilla and Snowball? Last summer they were neglected because I had to move away for the summer so I didn't get to water when they needed it. Other seasons they haven't done great either. They just start slowly dying off .
I enjoy reading your articles. (Devils Lake, N.D.)
A. Most of the shrubs you mentioned require fairly extensive sunlight. It could be they are not getting enough.
Also, you didn't say how old your landscaping was. Things change over time. Soluble salts in the soil and water, shade from adjacent trees and construction activity. All these factors and more can influence the health or vigor of a shrub planting. Once stressed by the environment, the door opens for opportunistic insects and pathogens to move in and cause their damage.
Q. How do shrub roses do in our area? Have you had any experience with Robin Hood? Is the care required less than for tea roses, and are there any drawbacks to growing them? (Eureka, S.D.)
A .In general, shrub roses are quite winter-hardy and adaptable to our area, not needing the fuss of the teas and floribundas. I have no experience with Robin Hood, but my references tell me it is completely hardy. Enjoy.
Q. How do I prepare my Freedom rose hedge for our N.D. winters--against the cold and varmints? I ordered it from Spring Hill Nurseries and they say it doesn't really need any special fall preparation. It bloomed beautiful long stem red tea roses all summer. Thanks. (LaMoure, N.D.)
A. Not need much care from the cold in N.D? I suspect they want to sell you some more roses.
Basically, these Freedom roses will not survive temperatures much below 5 degrees Fahrenheit. Consequently, I would give them all the protection you can afford through the winter months: soil mounding, leaf mulching, Reemay or similar covering. This all starts in about mid-October after the temperature has steadied or averaged below 40 F. I would spread some cayenne pepper around the base of the plants to discourage vole activity, or you could use a physical barrier like hardware cloth.
These are worth protecting as they are beautiful, prolifically flowering plants.
Q. I have enclosed a few leaves from a winter hardy Lillian Gibson rose. Three years ago the new spring growth froze off following a cold snap. Since that time the plant has become smaller in size and the leaves will turn yellow and fall off. It had just a few blooms this year and once again the leaves fell off.
Also, thanks to one of your Hortiscope columns in the Farm Forum pages, I have been able to locate a pre-emergent without purchasing a lawn fertilizer combo for crabgrass. Will the seed of crabgrass be fertile when it continues to form a head after being sprayed with Roundup or Trimec? Thanks for your help. (Mitchell, S.D.)
A. I have just one concern--Trimec and Roundup are not pre-emergent herbicides and are not used in the control of crabgrass.
Several pre-emergents are available: Pre-Em, Tupersan and Dimension. All are applied in the early spring around lilac blooming time.
Concerning the crabgrass, the answer is yes. The plant is killed, but not the seed.
Your rose sample has a bad case of black spot, Diploearpan rosae, a fungus disease brought on by high humidity and splashing water.
Several fungicides are available for control. Look for something with chlorothalinol or triforine. Application should be made as new growth emerges--every 10 days or so.
Also, avoid spraying water on the leaves. After pruning back in the spring while the plant is still dormant, spray the canes with lime-sulfur for sanitization.
Q. I am looking for yellow shrub roses. The seed catalogs and nurseries I have checked have several other colors, but not yellow. Could you direct me to a source? Or perhaps a reader of your column would have a shrub or two they are willing to sell.
Thank you for your assistance.
Your column is most useful. (Mayville, N.D.)
A. You can contact your local garden center, Town & Country Gardens, as they handle shrub roses and could very likely locate the yellow flowered ones you want.
I try to encourage people to shop locally if they can, before going to catalogs. The satisfaction is usually guaranteed and the quality better.
Q. I am sending leaves from a rose bush and I wonder if you could tell what kind of rose bush it is. It blooms all summer long.
Thanks for all the helpful advice you have given over the years of printing this column. Zeeland, N.D.)
A. I am afraid I will not be much help other than telling you it is a prairie rose of some kind.
Sorry! Thank you for the compliment about the column. I hope it continues to serve your needs.
Q: Last year I planted 12 hedge roses and they did very nicely. I dead headed the spent blossoms. Now, someone has told me that should not be done on hedge roses. What is your opinion on that? Also, I did not cut them down last fall. How should they be trimmed now in the spring? Should I cut only the tops since they are a hedge? They were about 2 feet tall last summer.
A: Hedge roses don't need as much fussing as the others. They need almost no pruning except to remove the diseased or dead winter wood, along with getting rid of anything that is tangled and non-blooming.
Q: I moved a pink rose shrub (the variety was never known to me) and apparently a little root was left behind for a new rose grew up in its place. It has not flowered yet but I am wondering if there is any chance of it being a clone of its parent. I thought it would not be, as many roses are grown on different root stock. But perhaps rose shrubs are a unique case. The reason I ask is the parent plant is failing and I thought if it was a clone I'd use it instead. It hasn't flowered yet so I cannot tell you much more. Perhaps I'll just have to wait and see what flowers it produces. (Fargo, N.D., e-mail)
A: It may or may not be a clone of the parent. Check the parent bush and see if there is a knot where the bud graft was performed (at the base of the plant). If there in none, then the sucker growth you see coming from the root is indeed a clone. If not, then it is likely a hardy rose stock not known for any great flowering ability, just hardiness.
Q: It seems the entire top part of my hedge roses are dead. Should I cut them way down? I think there would only be the base of the plant left. Would that be OK? (Harwood, N.D., e-mail)
A: Cut them all the way down and see what comes up, if anything. If they are alive, this will not make any difference, and come to think of it, it won't make any difference if they are dead! So you really have nothing to lose!
Q: I have a miniature rose bush that's about 2 years old. It's doing great, but I noticed that near the very bottom of the plant the leaves are turning yellow on some branches. What should I do so I won't lose the plant? What could be causing this? (e-mail)
A: Miniature roses are nitrogen sensitive. If the leaves are turning yellow from the bottom up, that is my first best guess. Nitrogen is transported within the plant to the new growth. It is done so at the sacrifice of the old growth when there is insufficient nitrogen available to the plant. If you have mulched the rose with wood chips recently, this could cause the nitrogen to be tied up, and unavailable to the plant. I suggest an application of Miracle-Gro or something similar once a month during the growing season.
Q: I just planted four rose bushes, all being hybrids, and they are in good sun, but out of four one went into shock (I think) from being transplanted, even though I used Safe vitamin B1. I am constantly having problems with my plants going into shock, especially hydrangeas. I usually have to deadhead all my flowers and a handful of leaves after transplanting. Is there something I am doing wrong or is this just to normal? Also, I was wondering if fish emulsion is really that great of a fertilizer. I use it on all my plants, but I want an experienced opinion. I have some well-decomposed steer manure, but I was told by someone less experienced than myself not to put it in this time of the year because it will burn the soil. True or false? (e-mail)
A: Generally, the shock you describe is normal. Most hydrangeas are greenhouse grown under ideal conditions, and when they are moved into real world settings, the show their distaste by dropping leaves etc. As long as they come out of it, don't worry. The fish emulsion and the composted steer manure are both fine for use in the garden. Both are low in nutrients and would be almost impossible to get a burn from either, unless someone spiked them with some extra nutrients to make them more potent! Use either without worry!
Q: I am trying to locate a plant called Linton Rose (Hellebrous orientalis). It is an evergreen plant and that is the extent of my knowledge. Can you help me with the correct name of this plant so that we can find a place to purchase it. (Lanesville, Ind., e-mail)
A: Thanks a million for the botanical name. The common name I have listed is the Lenten rose. A letter or two difference in spelling makes a big difference!
Anyway, the Lenten rose is related to the Christmas rose--H.niger. The leaves are more glossy green and serrated than those of H.niger. Flower colors vary from a dark maroon, to pink, and a cream color. Lenten rose self-sows abundantly which makes it a good plant for naturalizing among shrubs or trees that are deeply rooted. Lenten rose is hardy to zone 5, which makes it hardy where you live. Enjoy!
Q: I have a miniature rose bush that I received for valentines day. It bloomed beautifully, but the pot seemed rather small so I repotted it in May or June. The leaves are turning yellow now and falling off and it isn’t blooming. I use Miracle Gro in the water that I give it. Also, I have peace lily that I have had for a couple of years. It doesn’t seem to grow much and doesn’t bloom. I also use Miracle Gro on it. I keep them both in a south window with a front porch so they do not get direct sunlight. (LaMoure, N.D.)
A: You are growing two plants with differing light requirements in the same location. The porch is ideal for the Spathiphyllum, while it is inadequate for the rose. Try to gradually move the rose into increasing hours of direct sunlight to see if that doesn’t help the situation. Start with 30-45 minutes the first day and build up from there, until it is getting about six hours. With the lily, just be patient!
Q: I have two climbing roses which are about 7 feet tall. I pruned them once this summer and they are the same height again. Do I prune them for winter and how far back? (Grafton, N.D.)
A: You can prune them again this fall. If your goal isn’t to cover a fence or trellis, then cut them back far enough to cover them with a bushel basket or some other cover, after mounding soil over the crown. Otherwise, you have to carefully lay the canes in a trench and cover the entire thing with ample soil.
Q: We planted a common wood rose about four years ago. It is now at least 6 feet tall and seems to have done well, until this summer. Quite a few canes, mostly lower ones, seemed to die off. Checking closer, I found that the canes had in fact broken off. And, at the point of the break, the stem was enlarged. If the cane were 3/8 inch in diameter, for example, there would be a barrel-shaped enlargement that was perhaps 1/2 inch in diameter and nearly an inch long. That's where the break occurred, often low on the plant. I haven't been able to determine what caused the swelling and subsequent breakage. We had a similar situation earlier this summer with our downy hawthornes, which are now about 8 feet tall. Through the early summer I would find that the end of branches (perhaps the last 6 to 8 inches) had died. Again, there was a break of the stem, although I didn't notice any enlargement, growth, or reason for the breakage. Is there something we should be doing for either of these problems yet this fall or next spring? (E-mail reference, Mandan, N.D.)
A: Both the rose bush and the hawthorn are in the rose family and are subject to gall problems. One in particular, the crown gall, sounds like it is doing the work on your rose bush. It is more of a parasite than a pathogen and can weaken the canes it attacks, causing the breaking off that you describe. Even though it isn't the crown of the hawthorn that is being attacked, I believe it is the same organism, as it is known to attack the branches of apple, pear, cherry, and hickory, to name just a few. There is a possibility that a stem girdler (an insect) could have caused the breakage on your hawthorn since you didn't notice any swelling. I suspect the gall fungus, though, since it was in the area where rose bush was attacked. To be sure, you might want to check the branches where the breakage occurred to see if there is a possibility of borer activity at that point. They often lay eggs on branch tips and the larvae, about the size of mechanical pencil lead, would bore under the bark, girdling the stem causing dieback and often death to the tip. Where it is for sure the gall, the only control for homeowners is sanitation. That means cutting out all infected plant parts and disposing of them. None of the over the counter fungicides are labeled for control.
Q: Do the wild rose seeds I picked from the road ditch have any chance of growing? I dried them near a fan at room temp for a few days. Do they have to have a cold soak? Will I need more than the 2 teaspooons of seed to compensate for possible low germination or viability? Is it better to direct seed or can I start them indoors? Any guess on what the small white grubs in many rose hips are? The hips that have grubs have small holes as if an insect laid eggs, and I might have seen an egg in some of the hips, but I threw away any thing that looked like a grub egg or in any way damaged seed. (E-mail reference, Fargo, N.D.)
A: Rose hips should be collected as soon as they are ripe but before the flesh starts to soften. Stratify the extracted seeds immediately at temperatures ranging between 35 and 40 degrees for up to six months. If this is not acceptable, then simply sow the seeds in a prepared bed in a row or scattered over the prepared area. The seedlings will emerge next spring. Concerning the insect, it is a rose hip borer. Simply throw those hips away where penetration has been made.
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