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

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I am looking for some help. I have a spot in my lawn where grass won’t grow. It is a very shady spot and has silty soil. (e-mail reference)

A: Go for navigator creeping red fescue or another locally available cultivar of creeping red fescue. It is very shade tolerant. If the grass doesn't grow, then opt for some other type of ground cover.

Q: We have six mature maples (more than 30 years old) in front of our house. Two are within 10 to 12 feet from the foundation. My husband wants to cut them down because of possible damage to the foundation. They also are seeping sticky sap on the cars in the driveway. Will the roots damage the foundation or the waterlines of our house if we leave them? I love them, but they are blocking any view of the ocean. (e-mail reference)

A: Sorry to hear the maples are a source of aggravation for you and your hubby. If they haven't done any damage to the foundation up to now, they very likely are not going to do so in the future. The sticky sap is a temporary inconvenience. The sap is the result of aphid feeding activity. I would encourage you to save as many trees as possible because you cannot replace 30-plus years of growth overnight. I suggest making contact with an International Society of Arboriculture certified arborist at for a recommendation. Through treatment and proper pruning, you can be rid of the pests causing the sticky mess and open the canopy so that you can enjoy your ocean view.

Q: I have a birch tree that is included within some other landscaping in our yard. We have mulch around the tree and other plants. Hundreds of birch seedlings have started to grow in the mulch and makes our landscaping look like it is full of weeds. What can I do to kill the seedlings and is there anything that I can do to prevent this from happening? (Omaha, Neb.)

A: They should be killed off by the winter weather. If you want to be sure, get some RTU Roundup and use it diligently around the area to kill the seedlings. Before any weeds emerge in the spring, use some Preen in the mulch according to the directions and water it in. This will keep any future seedlings from coming up for just about the entire season.

Q: I got this plant about six months ago. After planting it, I started to have growth from four umbrella plants, but then the growth stopped. I repotted about a month ago because of spider mites. I put it in a large clay pot. It went into shock for about two weeks but then came back. I watered it too much and now it looks like it is getting sick. I love this plant very much and don't want to get rid of it. I have it in my patio window, so it gets very good indirect sunlight from 3 p.m. until about 7 p.m. The leaves are not turning brown or yellow. (Bloomfield, Mich.)

A: Gradually back off on the watering. It sounds like you have been so fastidious about your watering that the plant has not had a chance to dry between cycles. From what you have told me, the plant went through the growth cycle earlier and is now in a resting or dormant stage, so let it alone! Ramp up the watering a little when it is ready to send out new growth, which is usually in the spring. Allow the top part of the soil down to about the first knuckle on your index finger to dry before watering again.

Q: A neighbor planted three ficus trees next to our driveway. I see ficus trees in the neighborhood that have tremendous root systems, so I feel the roots are going to undermine my new driveway. My neighbor assures me that it will not happen. What do you think? (e-mail reference)

A: I think your neighbor is providing you with assurances he or she cannot guarantee. I would suggest installing a root barrier between the tree and your driveway. I understand your concern because of the cost of concrete driveways. I had mine replaced two years ago. The sticker shock still haunts me! Contact a landscaper who is familiar with BioBarrier. It is a material that is used all over the country to keep roots in check.

Q: I have a rose bush that is tall and wide. It has gotten this big because it puts out so many suckers. They are coming up 5 to 6 feet away from the original plant. I could be pruning every few days to keep it down. Can I spray the sucker growth with a herbicide of some kind without killing the entire thing? I love the scent of these roses and it is beautiful when in bloom, but it is taking over the flowerbed and walkway around it. (Cooperstown, N.D.)

A: Any herbicide that will kill the sucker growth also will have a detrimental effect (kill it!) on the mother plant. The plant is under stress of some kind. There is a material called "Sucker Stopper RTU" that you could use, but it is temporary and meant for the occasional sucker. I suggest taking a cutting or two from the mother plant that is not producing flowers and attempt to get them to root. If you succeed, dig out the current beast and replant with one of the offspring. Put a barrier around it to keep the roots in check somewhat.

Q: I have what I think is a European birch that is at least 40 feet tall and in the middle of a grassy area. The tree seems to suck all the moisture out of the grass, so I need to water the grass a lot. Should I not have grass in this area or what do you suggest? Other than the constant depositing of limbs, leaves and birch snow, the tree is great. (e-mail reference)

A: It would be better if you could grow another ground cover under the canopy. Look for low- water-requiring perennial plants that would thrive in your area. Having a lawn requires constant mowing that compacts the soil. This makes it tough for both species to extract what water is available. Core aeration may be an option because it would increase both the water infiltration and percolation into these comingled root zones. Having the water become more readily available to both species will reduce the necessity of such a high frequency of watering.

Q: I purchased a house in St. George, Utah. I would like to plant a row of shade trees next to some horse corrals and a stable. As there are no trees there now, I'm looking for trees that grow fast. I am leaning toward a poplar hybrid because it apparently doesn't have cotton like the other cottonwoods. After reading your column, it seems there are a lot of problems with cottonwoods, so I’m unsure about that choice. Is this a good tree or would you recommend something else? (St. George, Utah)

A: In St. George, the hybrid poplar would be the best bet for you. Poplars have problems, but in your environment, many would not because of the drier, semidesert climate. Nothing will grow faster or provide quicker shade, so I would encourage you to seriously consider this species. I would check with what your county Extension agent might recommend. Go to for a list of Extension agents in your area. There might be a species that would be a better choice.

Q: I have been very impressed with the information and content on your Web pages. I was wondering if you could confirm a suspicion I have about a (Norway?) maple in my backyard. I live in Ottawa, Canada. We have been experiencing a very wet and cool summer. The leaves have what I think is anthracnose or leaf scorch starting to show up on the lower leaves. There is a branch that has wilted from the edges in. I have attached a few pictures. I was wondering if there is any treatment for this or just nature at work. (e-mail reference)

A: That indeed is a Norway maple. The symptoms suggest an anthracnose infection. This fungal disease often follows cool, rainy periods that might be typical during spring months, but also extend into the summer. There is nothing to be gained from any fungicidal spray at this time. It must be pre-emptive to be effective and often is not needed. The best approach is good sanitation this fall. Dispose of the fallen leaves. If it appears that another extended rainy season is on the books for next spring, spray the tree with a fungicide containing mancozeb or whatever is legal in Canada. As a sweeping generalization, this disease comes and goes using good sanitation measures and the luck of the draw as it relates to weather. Other than the affected foliage shown in the photos, the tree looks robust and healthy, so it should handle this infection without long-term detrimental effects. Thanks for the very nice compliment about the Web pages!

Q: I need to know how to store cally lilies, cannas, dahlias and amaryllis bulbs for winter so we can plant them next year. (e-mail reference)

A: All pretty much the same way. Store them in a cool, dry and dark location. You can dust them with sulfur flour to reduce disease and insect problems, but that is about it. Don't attempt to store anything that has been damaged by handling or is showing even the slightest signs of disease or insects.

Q: I transplanted my iris plant last fall, but it did not bloom this spring. Is there something I should do this fall to encourage blooming? (Parker, S.D.)

A: The iris may have been planted too deeply. Peony and iris plants are sensitive to this problem. They will produce foliage, but no flowers. I would suggest pulling some of the soil back from the rhizomes so that no more than about an inch of loose soil covers it.

Q: I planted peonies this spring. To my surprise, they came up. Do I have to cover them for the winter? (e-mail reference)

A: Unless you live inside the Arctic Circle, you don't need to cover them. Allow the frost to kill the tops. The choice is yours then to allow them to remain until next spring or cut them off now. If these peonies are sited correctly, there is a good chance they will outlive the two of us!

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

Source:Ron Smith, (701) 231-8161,
Editor:Rich Mattern, (701) 231-6136,
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