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

By Ron Smith, Horticulturist

NDSU Extension Service

Q: One of my cactus plants has a circle of small cacti (if that’s what you call them) growing on top where the flowers were. How do I get them into pots without damaging the parent plant or is it impossible? I do not know if I should have taken them off earlier or removed the flower/seed before they started growing. (e-mail reference)

A: This is nothing to worry about. Cut those little cacti off the mother plant and allow them to heal for two to three days in open air. After that, plant them in pots. The mother plant will heal as well, so enjoy!

Q: I have a silver maple tree that is about 20 years old. I want to start a new tree from this existing tree. How do I start a new tree? (e-mail reference)

A: You can use seeds or seedlings. Seeds require no after-treatment upon maturing and will germinate in any nook or cranny they land in. That would be the easiest way to go. You can try softwood cuttings from this past season's growth. The cuttings will or should root in six to eight weeks with a hormone treatment. I would wait until March or April to do it. It depends on where you live, but do it before leaf out. Stick the cuttings in coarse sand so you can keep them moist by misting.

Q: I purchased a home in a newer development with no trees or shrubs in my yard or any of the neighbors’ yards. I'd like to plant a hedge of common lilacs around the perimeter of my backyard for some privacy. I do have a chain-link fence. How close can I plant the lilacs to the fence? Should I use landscape fabric under the mulch? I plan to put edging against the fence to keep the mulch from spilling into my neighbor's grass. I'm also concerned about the lilacs sending suckers under the fence into my neighbor's yard. I’m not sure if landscape fabric and edging will prevent that from happening. Would it be better for the lilacs to put mulch directly on top of the soil and leave out the landscape fabric? (e-mail reference)

A: If you stay away from common lilacs and go for nonsuckering cultivars, your worries will be over. You don't need the landscape fabric, so just use bark mulch. Look for Miss Kim at your local nursery outlet. It is a cultivar of the Manchurian lilac, not the common lilac. The Manchurian will grow to 6 to 8 feet tall with a spread of 4-plus feet.

Q: We have a raspberry patch in the backyard that is on the edge of our property. It was there long before we bought the house. However, we now have a new neighbor who has made a comment that there are shoots coming up in his yard. He also has a tendency to use herbicides. Although it is challenging, we have been making an effort to minimize our use of herbicides. In any case, if our neighbor uses herbicides, such as Roundup, on the shoots coming up in his yard, will that make it unsafe for us to consume the raspberries on the main plants in our yard? Some are just a few feet from the shoots. (e-mail reference)

A: If Roundup was going on the fruit-bearing canes, they would be dead. Being that they are not, you basically have nothing to worry about. That said, I'm with you concerning the use of herbicides around edible plant material. What I have done is put a root barrier between my plants and the neighbor. It should go down at least 6 inches to be effective. While raspberries are among the most delicious and healthiest of fruits, their rambling ways sometimes can be a pain to control.

Q: Could you recommend a shrub or small tree that will get 4 to 5 feet tall and 3 to 4 feet wide? It's next to a sidewalk. I'm replacing an arborvitae that's about that big. (southwestern Minnesota)

A: One of my favorites is the dwarf winged euonymus. It has outstanding fall color and should stay within the bounds you specified.

Q: I would like to plant an apricot tree in my yard, but I have a few questions. You say that early spring is best for planting. I assume that mid-May is too late to be considered early spring in northern Illinois. In this zone, we are encouraged not to plant most things until after May 15, which is when the frost danger passes. Is this too late for apricots? When would be ideal? What varieties do you recommend for this climate? Is there a well-producing dwarf variety? My yard is not terribly big and I wouldn't mind having a smaller tree. Is it a bad idea to plant a tree next to the house? How much space should I allow? I realize this may depend on the size of the tree. I don't want to have problems with the roots running into the foundation. (Chicago, Ill.)

A: Plant bare-root plants as soon as the frost is out of the ground and before the planting stock breaks dormancy. Nowadays, trees and shrubs can be planted during the growing season because most are containerized, so there is no or very little root disturbance. Some good choices are moongold, sungold or goldcot. Plant two for best fruit production unless you have neighbors within one-quarter mile who have apricot trees. If there are any dwarf varieties, I am unaware of them. Generally, dwarf fruit trees are not dependably hardy in our area. Somewhere in the education of humanity, everybody was taught that planting trees close to a house will destroy the foundation. Where I have seen that happen is when there is a break or leak in the foundation. If that happens, the roots will follow the flow of water and could hurt the foundation. Unless you have a weak foundation that leaks, you shouldn't have any problems, especially with an apricot tree. I have pine, crabapple, birch and linden trees planted next to my foundation. Most have been there for 23-plus years, but no foundation problems have shown up. Plant the tree as close as is convenient for you and the tree. However, be sure to plant it outside the drip line of the roof.

Q: We are planting eight Nanking cherry trees. I am wondering about mulching around the base of the plants. They will be planted in fairly heavy soil. However, I have amended the soil to lighten it somewhat. What would be a proper mulch to put around the base to hold moisture and to repel grasses and weeds? (Minot, N.D.)

A: Everyone will have an opinion on this. Use bark chips or shredded bark, with the nod going in slight favor of the shredded bark because it seems to stay in place better once installed.

Q: Every year my 6-year-old silver maple has tons of orange nodules. However, the tree has not grown much even though it is supposed to grow quickly. Could it be mites causing the problem? By midsummer, the leaves are yellow but not dry like in the fall. Is this the iron deficiency you mentioned to others? We have a heavy, clay soil here in Winnipeg. Other than a shot of Miracle-Gro a few times a year, I never have fertilized it. Also, I want a columnar tree (that can adapt to our clay soil) that can be planted 8 feet from my house and not damage my foundation or grow roots up through the grass. I have tried Swedish columnar aspens more than once, but they all have died. It tends to be a wet spot. I was going to try a tower poplar, but I changed my mind after reading about it today. I would prefer something that grows quickly. (Winnipeg, Canada)

A: Go back to the upright Swedish aspen, but this time, plant it a little higher. Bring in some extra soil to improve the drainage (even if you have to build a mound). There are not too many good columnar trees that can be recommended for what you want. As for the silver maple, this is showing advanced iron chlorosis. This is something that is difficult, if not impossible, to correct once the tree starts developing severe symptoms. Try to get a hold of an International Society of Arboretum certified arborist who specializes in fertilization to find out if an injection of chelated iron or iron sulfate can save the tree. Typically, mites do not affect tree growth, but an iron deficiency definitely can, so the problem should be corrected as soon as possible.

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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