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

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I checked out the catalog from Potsdam Nursery. I also got your message about starting off raising hazelnuts as a hobby at first. As I learn about the business and get comfortable with the cultural requirements of the business, do you have any idea what size hobby I should start with? I am talking about acre size. I am still checking out the catalog because I don't know how far apart to plant the filbert bushes. It sounds like the process could get expensive because the charge is $130 for 20 plants. (e-mail reference)

A: We must have differing ideas about what constitutes a hobby. My idea of a hobby of fruits or nuts involves just a few plants, not acres. Right now, I have a few hundred square feet of raspberries and the same with strawberries. I also have three wine grape vines. The raspberries, strawberries and grapes are enough of a hobby for me. In a much younger life, I stepped into ownership of a small 23-acre farm. It had about an acre of strawberries and about two acres of raspberries. There was no learning curve for me. Thank goodness I was working with a couple of forgiving crops and didn't need all that they produced to live on! I think if you talk to Bill of Potsdam Nursery, he will be in a good position to advise you on planting density and other concerns. Some other links for information are, and Good luck.

Q: If I keep my new dwarf cherry and blueberry trees growing all winter, will they bear fruit earlier in their life than if they were taking the winters off? (e-mail reference)

A: The short answer is no. These are temperate zone plants that need to go through the chilling process of winter and day length changes to function properly and move into sexual reproduction, which is the bearing of fruit.

Q: We planted a new lawn in the summer of 2008. We were told that if you mix grass seed with wheat seed that the lawn will grow and be more protected. I was under the assumption that the wheat would come up the first year and not return in the spring. However, the wheat came back in 2009 and 2010. Is there is something I can put on the lawn so the wheat does not come up again? We have worked very hard on growing a nice, full lawn, and this seems to be a yearly problem. (e-mail reference)

A: I seriously doubt that you have wheat coming up every year because wheat is an annual. I only know of experimental work being done in Washington State on possibly developing perennial wheat, which wouldn't have been in your mix. There must be something else coming up that is a contaminant in the seed mix or imbedded in your soil. When the snow finally melts, I would encourage you to bring or send a sample to me or one of the other turfgrass professors here at NDSU for evaluation and to identify what you have growing.

Q: Thank you for sharing your plant knowledge with the public. I appreciate your input. I live in central Pennsylvania (zone 5 or 6). In July 2010, I purchased a dieffenbachia plant for indoors that has adjusted well. However, when watering it, I noticed little white worms on the surface of the dirt. Do you have a recommendation for treatment? For the winter months, should I fertilize the plant? If so, what fertilizer is recommended? (e-mail reference)

A: This is nothing to worry about with the worms. However, if you want to control them, I’d suggest a drench of properly diluted insecticidal soap. It may take a couple of applications but it should do the job. Generally, fertilizing in winter is not recommended because most plants are dormant. As the day length grows, plants usually respond with evidence of some new growth, which is the best time for fertilizing.

Q: Are tulips toxic to grow among above-ground summer vegetables? I live in western Washington, where it doesn’t always dry out completely, so I am hoping the vegetables might help keep the bulbs dry to help them reproduce next year. (e-mail reference)

A: I cannot cite you chapter and verse from controlled studies that this is not something to worry about. However, deductive reasoning would tell me that you could plant vegetables that will not become poisonous by planting over these bulbs. Root vegetables, such as carrots, parsnip and turnips, probably shouldn’t be grown over the bulbs because of possible physical damage, such as intermingling, may cause.

Q: When I have a plant question, the NDSU Extension Service is one of the first places that I look. This time, I didn't find what I was looking for. My husband planted a row of cottonwoods along the western edge of our rather large garden to serve as a windbreak. The trees grew rapidly and look very nice. However, now we are having bad results with any vegetables grown in the area extending about 50 feet from the trees. Thinking that the soil needed a boost, I put a lot of manure (horse and chicken) in that area of the garden in the fall of 2009, but the 2010 garden still was a major disappointment. Even the weeds in that area did not appear to be thriving. On a hunch, I did a bit of searching and found that cottonwoods have some allelopathic properties, but really couldn't find much about it. Could this be what is affecting the garden? Can anything be done about it? Do the trees need to be removed? My current plan is to try to keep all leaf litter removed as much as possible and add organics, but if the trees do release allelopathic compounds, I cannot find if it's from the roots or leaves. If it's from the roots, I am sure that it is spread every time we till the garden. Would there be more benefit if we go with no-till methods? Are there some plants that would be more resistant to the compounds? Even our zucchini failed in the last few years. (e-mail reference)

A: It’s serious when zucchini fails! Actually, there are a couple of problems taking place. Poplars, such as cottonwoods, are voracious consumers of water and nutrients because of their aggressive, fast-growing root system. Give the roots an inch and they will take a mile, so to speak. The fact that you have such a well-tended garden by fertilizing and watering on a regular basis encouraged prolific root development in the cottonwoods, which deprives the plants of what they need to thrive. Allelopathy involves the ecological communications between species that can positively or negatively influence growth, behavior, reproduction and survival of associated species. In essence, it is the fundamentals of Darwinism at work, which is different species fighting for survival. In your case, it is the aggressive cottonwood trees exploiting local resources at the expense of your vegetables. Your addition of manure only helped the cottonwoods become dominant. If the cottonwood exudes the allelopathic chemicals the same as the notorious black walnut, then all parts of the tree (leaves and roots) will be making a contribution. Any of your considerations would improve the situation. What you might want to consider is having a trench cut about 25 feet away from the trees on the garden side and have a BioBarrier root barrier installed. Golf courses do this to prevent the greens and fairways from being dried up by tree roots. Building raised beds would work, but some type of waterproof barrier would need to be laid down first. Keep in mind that these trees are going to continue to get bigger, so they will be a source of ongoing problems such as falling branches. Unless you really need to keep these trees for windbreak protection, removing them might be another consideration.

Q: I have white fuzz on my cactus plant. What is it? (e-mail reference)

A: It probably is cottony cushion scale. I’d suggest taking a cotton swab dipped in alcohol and carefully dabbing each one to get them removed. The numbers will increase gradually and eventually overrun the cactus causing it to decline and then die.

Q: My cactus is in a plastic pot. Should I transfer it to a clay pot? If so, what is the best time of year to transfer it? (e-mail reference)

A: The answer is yes because clay pots are porous and will breathe, which plastic pots are incapable of doing. Clay pots will reduce the chance of overwatering. Transfer the plants anytime the plant is dormant and not showing any active growth.

Q: I have a very large Colorado blue spruce tree that is encroaching on my front porch, so I would like to cut several limbs off. I realize that the branches won’t grow back, but that is OK. However, will this damage the tree? (e-mail reference)

A: Functionally, it won’t damage the tree. As far as aesthetics, it depends on the kind of pruning job you do. Any branches you remove should be cut back to the trunk, so don’t leave any stubs.

Q: Three years ago, a relative passed away and my mom took home one of the roses. Today, she has a rose bush that has produced three roses. However, it is stemmy. Will it always be that way? Is it possible to make it grow more arms or is it best using a wood trellis and let it grow as is? (e-mail reference)

A: I’m assuming that the rose your mom took was from one of the funeral flowers. It is unlikely that the mother plant rose was a climber, but it could have been. You can advise her to cut it back every spring before it leafs out to get it to become bushier. However, if it has the characteristics of a climber, it will grow quickly into the long rose canes that seem to be troublesome for you. In that case, she would be better off training it into a climber and get the canes attached to a wooden trellis for support.

Q: I have a 20-foot-tall Italian cypress. The middle of the tree has turned brown, but the rest of the tree is fine and looks healthy. What can I do to eliminate this problem? I live in Florida and the tree gets plenty of afternoon sun. I have two other cypress trees that are perfect. I look forward to your answer. (e-mail reference)

A: How I wish I had the power to diagnose tree problems in Florida from North Dakota. My best guess is that this may be spider mite damage getting started or just the normal dying of older foliage that is being accelerated for some reason. My best advice is to contact your local Extension agent to see if a visit can be arranged to determine the problem. Go to to find an agent.

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) 231-7123,
Editor:Rich Mattern, (701) 231-6136,
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