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Hortiscope

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

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I have a very large basswood tree in my backyard. In mid-July, it starts dropping an incredible amount of thin, long, light-brown leaves and small, hard, tan-brown berries. Is this typical of this tree and how long should I expect it to last? (e-mail reference)

A: All of what you describe is normal for the basswood or linden. The brown leaves are really bracts from the base of the flowers/nutlets that the tree produces every year. It will stop dropping some time this month, but it depends on where you live. My own linden is doing the same thing. It is a small price to pay for such a majestic tree that has fragrant blossoms growing when nothing else is making a significant showing.

Q: We have a nice row of caraganas that were nice and green until mid-July. At that time, the leaves started to wilt and turn yellow. The leaves have since curled up, turned brown and fallen off. The tops of the branches are black. Most of the tree row is leafless in sections with spotted sections of green. We thought someone had sprayed the area with Roundup (we have reason to believe someone would do that), but someone said Roundup wouldn't do that. Some of the trunks are still green. However, most of the branches from the bottom up are bare and brown and look dead. For a while, it stopped, but it has started again. We live in Saskatchewan and have had a wet and cool spring. Last year we had a really wet and warm spring and summer. Should we cut them down? Do you know what is causing it? (e-mail reference)

A: Since the cambial tissue is still green, I would suggest that sometime between now and permanent freeze-up, you cut the caraganas down to just above the ground and remove all the cuttings. Burn the cuttings if possible. If they are going to recover, they should next spring with a flush of new growth. If not, then you've taken the first step toward getting them out of the ground.

Q: Your Web site is wonderful for a first-time homeowner. I acquired an heirloom peach tree that I had potted for two years. It is maroon/greenish and has long leaves. I planted it in my front yard. What is the basic care for this tree and how big will it get? I planted it next to my hawthorne tree. Is it true that deer like peaches? (e-mail reference)

A: Deer like peaches, apples, pears, plums, yews, arborvitae, plus probably at least another three to four dozen more plant species. Give the tree direct sunlight if possible. Do not fertilize it unless it shows some deficiency symptoms. Do intelligent pruning in the early spring before the tree leafs out. Water it during long periods of no rainfall and monitor the tree to be sure no pests get started. Use good sanitation practices, such as cleaning up fallen leaves and fruit. After all that, you should get an abundance of beautiful, healthy peaches. Lucky you!

Q: I planted a hollyhock alcea rosea that is blooming. It is listed as a biennial. Does this mean it will bloom every other year? Will it grow but not bloom next year? I am confused just what biennial means for the hollyhock. Thank you. (e-mail reference)

A: The term biennial means that the plant will remain vegetative the first year, then bolt and go into the reproductive (flowering) stage the next year. It then will die. With hollyhocks that are biennials, growers know that customers do not want to wait until next year for it to flower, so they treat the plants with a hormone or put it through an artificial cold period. By doing that, the plant either will be in flower or will flower shortly after planting. Depending on your climate, hollyhocks are perennials or biennials. In zones 9 and 10, they are biennials. In zones 3 to 8, they may live through the following winter and bloom again if you cut the faded flower stalks off at the base.

Q: I recently came across your great NDSU Web site. The format is fabulous. In the ‘70s, the previous owners of my home dumped concrete gravel, rocks, ceramic tile and other material in an area and then built a deck over it. We've had a thin layer of grass there for 10 years. The area butts up against asphalt. This year, I put in a herb garden for aesthetic reasons. I turned the grass over as best I could and layered the area with black cloth. At most, I put on 2 inches of top soil/compost to even things out. I bought and transplanted herbs by cutting through the black cloth to get the roots in. This is the lazy method, but everything is growing well and looks adorable. Considering the soil/concrete situation, are my herbs safe to eat or will I poison myself? The sage, thyme, bronze fennel and lemon verbena are mostly for show, but the chives and parsley are amazing. I put in rhubarb that I would like to eat in a year or two. Is there a soil test that could determine toxicity? Should I just build up the soil higher? Should I just grow the edibles in pots because there's no way to tell? (e-mail reference)

A: Herbs are the answer for this kind of situation. The fact that they grew so well is an indication that they have found their "home" in this solid waste dumping ground. I don't think you have anything to worry about as far as poisoning yourself. You didn't mention that any toxic chemicals were dumped there. Even if they were, after 10 years of grass growing, rainfall and watering, any toxic substances probably will have been greatly diluted, denatured or leached beyond the root zone of these plants. Enjoy because I certainly would!

Q: Our lawn is hard to dig through, so I am thinking that the water is not getting down to the roots. Would it help to use an aerator? If so, when would be the best time to do it? (e-mail reference)

A: Right now would be a very good time to get the aeration done. Water the area 24 hours ahead of time or aerate within a day or two after a good rain. Then overseed and fertilize and your lawn should shape up nicely.

Q: We planted a dogwood in July and have kept it moist. The planting took place following a month of rain. It faces toward the southwest, so it gets many hours of sun per day. We have been going through some blistering heat. I have been careful not to water the upper part of the tree, just the ground around it. However, the leaves are turning brown. From a distance, the tree has a brown look to it. I'm heartbroken because the tree was expensive. Does this necessarily mean it's dying? (New Hampshire)

A: Not necessarily. The problem could be just heat scorch. Keep it moist, but not too moist. It should come back for you next spring. It just needs to toughen up to its new environment.

Q: I saw something this weekend that I never have seen before. We have lilac bushes blooming for a second time this year. About a month ago, we had a very bad hailstorm. We’ve also had substantially more rain this summer. This weekend, I noticed that several lilac bushes are blooming again. What would cause this? (Arvada, Colo.)

A: The hormonal requirements for the buds to break dormancy must have been met in some manner, such as low temperatures, some kind of stress or the hailstorm. These are just guesses.

Q: I bought my first house about three weeks ago. I believe there is a maple tree in my backyard. I know that it might be too far south where I live to have a maple. When I moved here, a branch had leaves that were much yellower than the rest of the tree. Since then, I've seen all the leaves decline. Is it just the heat that is causing the leaves to turn brown or is it something more serious? (Belton, Texas)

A: Your tree is a silver maple. From the looks of it, the heat is taking a very devastating toll on it. This never will develop into a good-quality landscape tree in your part of the country. It might hang on and barely survive, but that will be about the best you can expect of it under normal care and weather conditions. Also, you might have a high soluble salt content in the root area based on the firing of the foliage edges that I see in the photos.

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 ronald.smith@ndsu.edu.


NDSU Agriculture Communication

Source:Ron Smith, (701) 231-8161, ronald.smith@ndsu.edu
Editor:Rich Mattern, (701) 231-6136, richard.mattern@ndsu.edu
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