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

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I have several questions about gardening. I have a plum tree with many blooms but very few plums. Why would this happen? Those that grow mostly are small and turn red and blue. There is a brown film or coating around the pit in midsummer. Why would this happen? I live in zone 3, so I am wondering if it is advisable to try to grow apricots. I was told that they seldom bear fruit. I plan to plant some Carmine jewel dwarf cherry trees. Should they be planted close together or can they be 200 feet apart? They are approved for zone 2. I had some Fort Laramie strawberries for three years. They didn’t bear a lot of fruit but spread lots of runners. Then the plants quit bearing fruit entirely. I put some Gurney's Strawberry Food (fertilizer) on them. They are in the shade by 3 p.m. Thank you for your help. (Sheyenne, N.D.)

A: Your plum questions relate to several possible problems. It could be an incomplete fertilization by pollinating insects. If the bees are scant in number or if the weather is not conducive to pollination, such as windy, rainy or cold, that would limit the number and size of the fruit. All plum trees will do a better job of fruit production if there is another plum species nearby. It is not advisable to attempt growing apricots in North Dakota, unless you have the patience of Job. You can go three, four or five years without any fruit but then have a couple of years in a row with decent fruit production. However, the tree may die the year after or remain vegetative for a couple of years. Depending on winter extremes, the tree may die from exposure to extreme cold. Your Carmine cherries can be whatever you desire. Planting them close together gets you a handsome hedge but also a greater chance for disease problems as they age. The fact that your strawberries produced lots of runners is a possible indication that they were getting too much nitrogen or had a virus that impacted fruit quantity and quality. As a sweeping generalization, it is recommended that a planting of a particular species of strawberries in one location be looked upon as a temporary planting that will bear well but then begin declining because of a virus. Once this is noted, I suggest tearing out the plants. If possible, locate the new patch in a different location and use fresh stock. The former planting site can be turned into an annual vegetable or flower crop. I hope this information answers your questions.

Q: My ficus tree is growing beautifully in my backyard. We cut down a tree that was growing near the ficus tree. However, after cutting the tree down, we noticed that the tree was growing into the ficus tree, so now the ficus tree has a big bald spot. There are some small branches and leaves growing in the bald area. How long it will take until the ficus is full in that bald area? (email reference)

A: Leaves will grow where the sun shines, especially when it comes to ficus trees in an outdoor environment. I have no idea how long it will take because I don’t know the overall condition of the tree, environment it is planted in or soil conditions. You could help regrowth along by practicing safe fertilization, which means not overdoing it. If this is something you don’t trust yourself with, then hire a certified arborist to do it properly. Some selective pruning also might help.

Q: A man just called to tell me that his caragana plants have a lot of dead areas. Can he trim them back? If so, how much and what time of the year is best? (email reference)

A: Anytime between now and just before new growth begins is a good time to trim the plants. In other words, whenever the spirit moves him to do it. They can be cut back to short nubs as close to the ground as possible. They will burst forth with a flurry of new growth this spring.

Q: I planted some silver maples using volunteer seedlings several years ago. They have grown vigorously since then. However, I planted one too close to the house, but I was able to get someone to move it. After it was moved, our cats decided to sharpen their claws on the trunk. They clawed most of the way around the tree. The rather thin bark is scraped away several inches vertically. The trunk is 4 to 5 inches in diameter and protected with a chicken wire sleeve. What can I do to keep the tree alive? (email reference)

A: Naughty cats. However, based on what you have told me, I don’t think the tree will have any trouble recovering on its own. The wounds should heal and leave a protective scar tissue. I would leave the chicken wire wrap on until the tree develops a corky bark in a few years. Be sure to move the chicken wire out in response to tree growth as the years pass. You might encourage it along this spring with a combination of a light nitrogen fertilizer and chelated iron.

Q: I would like to use Siberian elm trees for screening a yard. Are they prone to disease problems? Can you list some pros and cons of this tree? (Fordville, N.D.)

A: Siberian elms have very few attributes. I will give you the positives and negatives. The growth is fast but the wood is brittle. Short of planting on the moon’s surface, the tree will grow under just about any conditions found on this planet. That the foliage will be ravished by insects is almost guaranteed. It is resistant to Dutch elm disease and phloem necrosis. Siberian elm is rated by horticulturists and arborists as one of the worst, if not the worst, of the world’s trees. Once established, Siberian elms will begin to die but never will die completely. It is totally lacking in aesthetic value for landscaping purposes. Siberian elms were planted by the government during the Depression of the 1930s because they become established and grow quickly to provide a makeshift shelterbelt/windbreak in the prairie states. In my opinion, just about anything else you pick will be a better choice than Siberian elm.

Q: I just came across your website and saw that you were answering questions about hibiscus plants. I live in southern California and just bought a hibiscus. I live in an apartment and don't really have a place to put it to make sure it gets at least six hours of sunlight a day. I bought a 150-watt plant light that is on for nine hours a day. Some of the leaves and buds have turned yellow and fallen off. I've had it a little more than a week. It did have at least a dozen buds on it when I bought it. Are the leaves and buds falling off because I repotted the plant? Is my artificial light inadequate? Have I possibly overwatered it? I'm new to plant care, but I really want this plant to do well because it has a lot of sentimental value. What do I need to do with it? (email reference)

A: Although a little fussy at times, hibiscus plants are extremely tough plants, so they seldom kick the bucket. I have some ideas on what may be causing your problem. Having been purchased from a facility that was providing optimal care and all the sunlight possible, it may be going through transplant shock. The light you are providing is inadequate. Full sunlight for 12-plus hours a day is needed. Also, put your timer up to at least 14 hours per day to compensate for the lower light intensity and replace the bulb in a year. If you repotted into a container that did not have free drainage, this could be contributing to the foliar discoloration and bud drop. If you used a potting soil that doesn’t drain well or are overwatering, it definitely will contribute to a plant’s decline. As a generalization, plants do not like changes in their environmental settings, so this is an adjustment period for the plant.

Q: I read the question about the Christmas tree that grew in water and thought I'd mention something that happened to me and my wife back in 1965. We lived in a small apartment and purchased a small Christmas tree in Moorhead. We trimmed off some of the lower branches to improve its looks. The tips of the branches left on the tree grew just like the ones mentioned in your column. The trimmed-off branches that we had stuck in a jar of water and kept on top of the refrigerator also grew. Not only did the trimmed-off branches grow, they also developed small, white roots. Unfortunately, we had no place to plant the branches or the tree. On another note, I kept a tuberous begonia this winter. It has continued to bloom, but the flowers are small and mostly single. The leaves also are much smaller than those that grew outside. Would it work to cut the plant back and fertilize it to get bigger leaves and flowers when I move it outside? (email reference)

A: Thanks for sharing the experience with your Christmas tree. It must have been a fairly fresh-cut specimen and loaded with hormones to grow shoots and put on roots. Leave the begonia as is. As small as they are, cutting off the leaves would remove the food-making structures that are needed for future growth. When planted in the outdoors with more light, heat and humidity, they will develop the appropriate leaf size. Thanks for being a reader of the column.

Q: My mother has a cactus plant that my father and I bought for her about 30 years ago. The original was a plain, round, spiky cactus. Through the years, it has grown a smaller ball on top of the old one and a third ball on top of that. The original ball appears dead. The second appears less dead but not in good shape. The most recent ball appears green and healthy. What should my mother do to keep this cactus healthy and alive? Do you cut the bottom parts off and replant? This is an unspectacular but terribly sentimental cactus, so she desperately wants it to survive. Please help. (email reference)

A: I would advise separating the baby from its ancestors and attempting to root it in a fresh cactus mix and using a new container.

Q: My 1-year-old jade plant is doing well. However, my daughter’s cat decided it would try to eat the leaves. I have relocated the plant to a new area of the house since then. However, the leaves are dying around the area where the cat caused damage. The trunk of the plant in the damaged area also seems to be having problems. In the past week, the plant has died back to about 3 inches from the soil. Am I safe to assume the plant will do fine or is there something I can do to ensure the plant will not die? (email reference)

A: If the plant has shriveled up almost to the soil line, it certainly sounds like it is dead to me. If it hasn’t responded to watering and the new location in a positive way, that is the only conclusion I can come to. You might try taking the plant out of the pot and checking the roots to see if they are alive. Sometimes cats will use containerized house plants as their litter box, which may be what is killing the plant.

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 email ronald.smith@ndsu.edu.


NDSU Agriculture Communication – March 21, 2012

Source:Ron Smith, (701) 231-7971, ronald.smith@ndsu.edu
Editor:Rich Mattern, (701) 231-6136, richard.mattern@ndsu.edu
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