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Ron Smith answers questions about flowers, trees, gardens and shrubs.

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I had someone call about a Rocky Mountain juniper. This winter, the snow really filled in and ended up splitting some branches. Can they trim it? Will it come back? (email reference)

A: The tree will not resume its original shape. If they trim the tree and leave the greenery on it, it will continue to grow in any manner it chooses based on genetics.

Q: I purchased a pink variety of hibiscus from a local store. I picked it for its multiple buds and broad leaves. However, once I brought it home, it appeared to be unhappy. I put it in an 18-inch pot using Miracle-Gro potting soil. The plant has new growth but the older leaves are curling and look as though they are wilting. The flowers also look wilted and lack color. What can I do to improve my plant’s quality of life? (email reference)

A: The plant is in a transplant funk. Keep the root area well hydrated, but not soggy. It will recover eventually. I also advise keeping it out of direct sunlight, especially the hot afternoon sun, until it can perk up. Hang in there and don’t give up.

Q: I live in northwestern Indiana. I purchased a very small bloomerang lilac. I would like to espalier it along a southwest-facing wall. However, I can't find anything on the Web about espaliering a lilac. Do you have any tips? Thank you very much. (email reference)

A: Horticultural art is very difficult, if not impossible, to teach by email correspondence. Basically, espalier pruning is vertical and horizontal pruning along a flat plane. It is a pruning technique that requires most major pruning be done while the plant is dormant and during the growing season to keep it along a flat plane. The Chicago Botanical Garden has a good article I found that should give you some guidelines. Go to for the information. You need to be experimental and not afraid to make small mistakes. You also need to be patient. It is something that only your mind can produce through you working with your hands.

Q: The house next door has had two poplar trees in the backyard for at least 50 years. We have no idea what kind of poplar trees they are. I'm worried about the trees getting into our foundation after reading your comments on the Web. We've always had problems with suckers since we purchased the house 17 years ago, but the suckers are going crazy this year. I tried to dig a bunch of roots out during the winter and the new owner of the property trimmed the branches. The problem is the new owner is not willing to cut down the trees. How can we get them to do that? (email reference)

A: Have the trees inspected for potential hazard. This will require a tactful approach on your part and perhaps a willingness to split the removal costs. I can’t imagine a homeowner trimming poplars that old. Poplars are notoriously weak-wooded trees. Poplars break up easily in anything approaching a summer storm. Trees that old may have internal rot, which reduces the tree’s ability to support itself. Go to to find a professional arborist. Be sure to check credentials and insurance before allowing any work. If this effort fails, you can have a root barrier installed between you and your neighbor’s property. There are contractors all over the country that install this material on golf courses to keep roots from moving to greens and fairways. The material is called BioBarrier and is guaranteed for 20 years. I hope you can get something worked out with your neighbor that is satisfactory to both of you.

Q: I have a neighbor who is about to plant a small garden. However, while tilling he noticed ants and would like to have them taken care before he does any seeding. My Ortho problem solver book tells me to use Ortho Diazinon crystals to take care of the problem. I've got an Ortho product called Ant B Gon. The primary ingredient is permethrin that I use on sidewalks and the driveway, so I can't see where it would be suitable for a garden. If either one of these products can be used, how soon afterward will it be safe to plant or would the product be flushed from the soil by the time the garden items are harvested? (email reference)

A: Permethrin has low mammalian toxicity. So much so, that it is used in clothing for military personnel if they are subject to insect bites or other annoyances. At least one Extension Service publication suggests using it in vegetable gardens to control fire ant mounds. My tongue-in-cheek advice is to locate the ant mounds and then apply the drench to eliminate the population. Plant the vegetable garden about a week later.

Q: I planted 300 Okanese poplars two years ago. The majority have done extremely well. This spring was unbelievably wet, so I have five or six that did not leaf out. The buds are there and the stems are green. What can be wrong? A few people have told me to cut them down, but the buds are there, so I am hesitant to do so. One other strange fact is that four of the trees appear to be in an alkaline or acidic soil area. Would that make any difference? (email reference)

A: This is Agricultural Canada's best hybrid male poplar, so I wouldn’t give up on them just yet. The Okanese was bred especially for alkaline prairie conditions. The trees should tolerate a wide variety of soil and climatic conditions, but certainly not extremely acid conditions. you need to get the soil pH tested to know what it is you are dealing with. There is no way of determining soil pH by looking at it.

Q: My mother died recently, so I have inherited her plants. One of them is a hoya that is at least 40 years old. She's had it since I was a child, so she obviously has taken very good care of it. I have no idea what to do with it, so it's not looking well after four months in my care. Some of the leaves are getting yellow around the edges. After reading your column, I think I might be watering it too much. We aren't living in the house, so the blinds are closed most of the time. As far as I can tell, she never repotted the plant. The way it's wrapped around the hanger, I can't imagine how to even begin getting it out to repot it. How can I tell if it needs repotting? (email reference)

A: Many times, good intentions end up killing a plant. I'd suggest leaving well enough alone for now. Work on the overwatering and getting the plant more light. Plants can be kept pot bound and alive almost indefinitely with proper management, which your mom apparently had a knack of doing. Once you get the plant responding favorably and if you still want to repot it, get back to me with some photos. We will see if we can work out a scheme to get it repotted successfully.

Q: I have whiskey barrels that I am trying to grow cucumbers and tomatoes in because I do not have a yard for a garden. So far, I have not been very successful in growing these plants. What am I doing wrong? Do I need special dirt or fertilizer? (email reference)

A: Container gardening needs well-draining soil and container. To accomplish this, you need to have a hole or several of them in the base of the container and you need to use soil intended for potted plants.

Q: I planted a row of 20 emerald arborvitaes two years ago. I noticed that some have brown tips on areas of trees. The one the most distant from the house has brown tips everywhere. I watered regularly the first year and applied shrub/tree fertilizer spikes last spring. Should I trim the brown tips? What is this problem? (email reference)

A: Arborvitae miner maggots cause the browning. Sprays are ineffective at this point, but the pest can be controlled by pruning out the branch tips and disposing of them. If this develops into a recurring problem, then an early application of a systemic insecticide with the active ingredient imidacloprid in it should be used. The insecticide will keep the juvenile stage of the maggots from emerging as adult moths and laying more eggs.

Q: We planted a maple tree in our yard 28 years ago. It tried to bloom this year but never did. The buds are on the tree but they are dried out. How can we save the tree? We live in Illinois and the tree is in our yard. (email reference)

A: This is bad news. It sounds like the tree has a systemic fungal disease, such as verticillium wilt or basal canker. There is no cure for both problems. I suggest that you contact a certified arborist to have the tree inspected or removed before it becomes a hazard. Go to to locate qualified companies or individuals. Be sure to check for credentials and insurance.

To contact Ron Smith for answers to your questions, write to Ron Smith, NDSU Department of Plant Sciences, Dept. 7670, Box 6050, Fargo, ND 58108-6050 or e-mail

NDSU Agriculture Communication – June 15, 2011

Source:Ron Smith, (701) 231-7123,
Editor:Rich Mattern, (701) 231-6136,
Prairie Fare: Prairie Fare: De-stress with Gardening  (2019-05-23)  According to researchers, gardening can be beneficial for mental, physical and social health.  FULL STORY
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