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

By Ron Smith, Horticulturist

NDSU Extension Service

Q: Earlier this summer, I picked up some maple seeds in the park and planted them in wooden boxes. Now I have little saplings. Winter will be approaching soon and I’m not quite sure what to do with the little guys. Do I have to move my saplings indoors? Should I leave them outside unprotected or protected? I planted the seeds in 4 inches of soil. Is that too shallow? Thanks and hope to hear from you soon. (Montreal, Canada)

A: It is always fun to play around with discovered seeds, especially when you get the response you did. The saplings need to stay outdoors and be protected somewhat. Because you have them in wooden boxes, I’d suggest planting those boxes in the ground somewhere on your property. This will keep the roots from being exposed to the low air temperatures that could reach lethal levels. Roots have a lower tolerance to low temperature extremes than the aerial parts of the plant. As another precaution, once the saplings have dropped their leaves, I would suggest placing a rose cone or bushel basket over the plants. Pack the covering with leaves to prevent low temperature damage and offer protection from bunnies or voles. Congratulations on your green thumb. We’ll nominate you to be our honorary arborist.

Q: I have two blueberry plants in pots. Should I store the plants in my garage for the winter or can I plant them now? I live in Canada, where the weather is starting to cool off. (Ontario, Canada)

A: Do blueberries grow in your community? You might check around to see if they do. If so, get the plants in the ground soon. Incorporate generous amounts of sphagnum peat moss into the soil. If not, then your only option is to bring them indoors, which eventually will spell their death. Folks in North Dakota also try to grow blueberries where they cannot. Inevitably, they end up either killing the plants or dumping them for lack of production or hardiness.

Q: We planted small-sized emerald trees last weekend. While we were putting them in the ground, we saw that there was an old layer of weed barrier under the river rock landscaping. I know that these barriers are supposed to let air through but the soil seemed damp to the touch. This made me wonder if the roots would get enough oxygen. What do you think? How often should I water the plants? If the soil feels damp a few inches down, how do I know for sure the root ball is receiving enough water? Are rocks OK as a cover? I left the circumference of the trunk free of rocks. Is mulch necessary? Lastly, we are supposed to have a frost tonight. Should I cover the tree? Thank you so much for all your help. I appreciate your patience with novices like me. (email reference)

A: Get them planted now or as soon as you can. I am not a big fan of weed barriers or rock mulch. Too much air is eliminated from the root zone by these barriers and the soil is kept too wet for too long a period. Stone is not a normal mulch in any shape, form or fashion. Mulch organic material is bark nuggets, shredded bark and wood or sphagnum peat moss. The purpose behind mulch is to modulate soil extreme temperature swings, retain moisture and help keep weeds down. In addition, the organic mulches break down during the growing season to add nutrients to the root zone for plant utilization. Make the organic mulch about 3 inches thick. Plant the emeralds and then water them in well. Forget them for the remainder of the fall unless a dry and warm spell carries us into late October. If that happens, give the emeralds one more good soaking before the ground freezes up or is covered with snow.

Q: I have an overabundance of weeds in my yard. The weeds are mainly crab and quack grass and creeping Charlie. Is fall the best time to spray? What product would you recommend using? I have the equipment to spray a liquid or use dry pellets. Thanks for your advice. (email reference)

A: Crab grass is a warm-season annual that Jack Frost will kill before winter arrives, so save your money. Applications of pre-emergent herbicides next spring when the lilacs are coming into bloom will go a long way in bringing this pest under control next year. The herbicides prevent the seed that was dropped this year from completing germination. Quack grass is a perennial and impossible to clean out of a typical home lawn without significant collateral damage to the grasses. I’ve found that it is easier to learn to live with it. As for broadleaf weeds, fall is the best time for control. Between now and mid-October is as close to ideal as you can get. For more information, go to If you turn to Page 11, you’ll see where I’ve listed some products to consider. Liquid applications always trump granular.

Q: We have a young oak tree that is very straggly. We had a beautiful oak that we lost during Hurricane Ike, so our son bought us this orphan very cheaply. The winter didn't improve it because we had some unusual frost days and then strong southeast winds off the ocean for several weeks. There are many dead twiglike branches, so we are wondering if we should prune the tree. We are watering when we can with a drip hose. Unfortunately, we have stage two water rationing, which doesn't help. What, how and when should we feed and water the tree? Any advice would be appreciated. My 80-year-old husband has decided that he has forgotten all the botany he learned at the university. Our seedlings are doing well. Thanks for any advice. (Galveston Island, Texas)

A: At age 80, he has a right to forget what he wants as long as it is his choice. I’m not about to give you information from North Dakota on an oak growing on Galveston Island. However, I’ll be glad to help otherwise by giving you a local contact. Go to to find someone close to you. If someone cannot answer this question, he or she certainly can connect with someone at Texas A & M who will be able to assist.

Q: I have had a thriving hibiscus outside on my lawn all summer. I am bringing it in for the winter and want to be sure that I do everything right. I have healthy indoor plants that I am very worried about because I never have done this before. Would you please go over the directions to be sure I do this correctly and not destroy any of my plants? I certainly do not want any bugs because my indoor plants are very bug-free. Can I put the hibiscus near a window in the basement? It certainly would not get as much light as it did during the summer. Thank you very much. (Toronto, Canada)

A: The hibiscus can be brought indoors bug free after cutting the plant back to 6-inch stubs. In a room separate from where you have your other houseplants, spread some newspaper on a table or floor. Use pasteurized potting soil and a fresh pot or be committed to clean the one you have. Have a bucket of insecticidal soap that is properly diluted and ready to use. The bucket or container should be big enough to accommodate the entire branching system of the hibiscus. Dip the top of the plant into the insecticidal soap solution or spray the top completely. Carefully knock all the soil off the roots and then gently rinse them under tepid water. Immediately repot in either the clean container or the new pot using the fresh, pasteurized soil. Water the soil until the water flows out of the pot. Let the pot sit for 30 minutes before watering again and letting the pot drain again. Move the plant to its new location and try to give it additional light energy from a plant light that has a 12- to 14-hour timer. If you follow these steps, you should not have bugs moving in on your refreshed plant.

Q: The “iris fairy” planted some wild iris plants in my boxwood shrub. I cannot dig them out without digging out the shrub. How can I kill the multiplying irises? (email reference)

A: Carefully take Roundup and paint the foliage with an artist’s brush. That should work. If not, then your only option is to dig everything out during the dormant season and replant without the interlopers.

Q: We have several lovely birch trees (white) that are 60 to 80 feet tall. They were planted on a landscaped incline very close to the back of our house. If one were to fall, it would take out a large portion of our roof. How easily do they topple? Thanks for your assistance. (email reference)

A: Not easily, but to be on the safe side, it would be a good idea to have an International Society of Arboriculture certified arborist inspect the plantings to be sure they are safe or make suggestions as to what can be done to improve the safety margin. Go to to find a certified arborist in your area. Check for credentials and references before allowing any major work to be carried out.

Q: We bought a house in Michigan with a 60-foot-tall maple in the front yard. It was fine until the kids kicked the side of the tree that faces south. There is now a large area of dead and peeling bark with gray wood below. There also is a 2-inch-wide slit in the bark heading up the tree. On the problem side of the tree, the leaves have started to turn much earlier than the rest of the tree. (email reference)

A: A tree of this majesty deserves some investment in trying to save it. I would advise getting in touch with a local certified arborist to inspect the damage. I am somewhat confused about the kids kicking the tree and causing that kind of damage. You must have some big, strong kids!

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 – Oct. 5, 2011

Source:Ron Smith, (701) 231-7971,
Editor:Rich Mattern, (701) 231-6136,
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