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

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I have an anglewing begonia that lives in my greenhouse. Its leaves began curling up in tight curls from the sides toward the middle and then turning brown. What do I need to do to treat this problem? (e-mail reference)

A: I don't know. It could be from herbicide drift (you didn't say where you live), mealy bug or mite infestations, or any number of fungal diseases. To save time, I suggest you contact your local Extension Service office to find out if there is a horticulturist or plant diagnostician who could assist you in getting the problem identified. Go to and click on your state and then county for your local office.

Q: Is the cyclamen toxic to small animals such as cats? (e-mail reference)

A: Cyclamen contain toxic saponins, although the number of serious exposures is very low. The plant was investigated for toxic and pharmacologic properties in the 1950s and ‘60s. However, there has not been much research since then that I can find. Apparently, the highly toxic part of the plant is the rhizomatous tuber, which the cat is unlikely to get into. However, I would do my best to keep the kitty away from the plant if possible.

Q: My croton lost all of its leaves. I live in Florida and have it planted outside. When we got a cold spell, I covered the plant, but I guess it couldn't take it and all the leaves turned brown and fell off. How do I know if it is still alive? (e-mail reference)

A: I'm relatively sure it is still alive. The stems should be green under the bark. If not, the crown should have life left in it. I'm willing to bet that with the arrival of warm, spring weather in your part of the country, it will begin to releaf for you. At the very least, it should send up some new growth from the crown.

Q: We travel a lot in the Arizona area during different times of the year. We see many beautiful cottonwood trees in the sandy valleys. However, why do we only see mature, very large trees and no new young trees? It's as if the trees are not reproducing. (e-mail reference)

A: I only have some guesses. Conditions are not satisfactory for the seedlings to become established. What you are seeing are males because the females have been removed to prevent the annoying seedlings from coming up everywhere. What seed that is produced is consumed by the wildlife immediately. Keep in mind that the desert is a stark place for abundant food, so anything that can be consumed is before it has a chance to establish. The next time you visit that part of the country, ask someone with the Arizona Extension Service the same question for a more cogent answer.

Q: Is it possible for an African violet to display stress because of workers suffering from colds or flu in an office setting? I have had two plants on my desk for quite some time, but have not had problems until now. Prior to my office, they did very well in my home. Yesterday, both looked just fine. When I came in this morning, I noticed that the larger one had developed three droopy lower stems. Nothing has been changed in their routine during the past eight months. The leaves and stems look fine, just droopy. They haven’t bloomed since last fall and don’t appear to show any signs of developing budded stems. Prior to this, they bloomed just fine. I water from the bottom once a week when needed. I use filtered water that is diluted with Peters African Violet Food. (e-mail reference)

A: How nice it would be to get a sympathetic acknowledgment from our houseplants when we are not feeling well! Unfortunately, this is not true. What has likely happened is that up to this point, the plants were silently suffering some kind of cumulative stressors, such as temperature, light, water, drafts, insects or disease, but didn't show any symptoms until now. It is somewhat like going somewhere where you get into unsanitary conditions, but the symptoms don’t show up until a few days later, so you can't make sense of what it is that ails you. As a sweeping statement (I've said this many times before), the majority of houseplant problems are from two sources: overwatering and/or underlighting. I think the problem may be too little light intensity. In an office setting, the fluorescent lighting degrades through time. The problem is little noticed by the human eye, but is picked up by the energy preceptors in the plant’s chlorophyll mitochondria as it fades in intensity. This is why changing the fluorescent lights on a yearly basis is recommended for optimal plant health and vigor. Our vision will notice the duller light intensity about a year or two later, so get the bulbs changed to make it easier on our eyes. Unless the plants in the office are tolerant to low-light conditions, such as the sansiveria or Chinese evergreen, they will react much sooner than the human eye can make the detection. The fact they haven't bloomed since last fall gives me a hint the problem may be the lighting.

Q: My sweet gum tree is starting to bud, which raised a question in my mind. Are the physiological changes (shedding of leaves or new buds) prompted by external factors such as too cold or warm, too much sunlight or not enough and moisture conditions? On the other hand, is the shedding of leaves or new buds brought on by some internal clock that couldn't care less about any external conditions? The reason I ask is the sweet gum has been dormant here in southern California since November (it dropped its leaves then). However, now it is sprouting buds although the weather is cold and rainy. Why is it coming to life now? (e-mail reference)

A: Woody plants are affected by all the factors you mentioned. One of the biggest triggers is the changing day length. As daylight hours shorten, the abscission layer begins forming. Depending on all the external and other factors involved, the leaves eventually senesce and drop off. The reverse happens in the spring. The buds pick up the lengthening daylight and begin to break out. Bud breakout is accelerated or held back by external factors, such as temperature and rainfall. To our rational minds, we'd like to think that the plants would break bud when everything is perfect for them to do so, but it sometimes doesn't work that way, which can lead to problems I won't bother you with at this time.

Q: I have a 5-year-old cherry tree. It has a few blooms, but never produces any cherries. I was told I needed a male tree to help produce fruit. Is this true and how do I tell a male cherry tree from a female? (e-mail reference)

A: No such tree exists. What you need to do is get another species of cherry tree (even a flowering cherry) that blooms at the same time as yours. What happens is that pollinating insects move between the trees and inadvertently carrying pollen with them. This causes fertilization to take place, which usually results in a very good fruit set.

Q: Last fall you had cautioned me against fertilizing the sweet gum while it was dormant, so I didn't. Does the new budding indicate it would like some food (fertilizer) now? (e-mail reference)

A: I really wouldn't fertilize now. I'm a big believer in responding to visible needs that show up rather than just providing nutrients in abundance when they are not needed. This can result in phenomenal growth, which is nice to think about and see, but it makes the plant more vulnerable to insect and disease problems. If the resulting growth appears to be sluggish, then I would consider giving the plant a little boost. Most of the time, fertilization at this stage of life is not needed.

Q: I received a ficus for Christmas. It is doing well, but it is in the original nursery bucket, so I want to transplant to a nicer pot. However, this is not the problem. I want to plant some queen's tears around the bottom of the tree for the visual aspect and to keep my cats from using it as a potty box. Will these plants be compatible? Is there another type of companion plant that I can plant around the bottom of my ficus? (e-mail reference)

A: The queen's tears, also known as a friendship plant, should be a good companion for the ficus. However, keep in mind that it is a drought-tolerant, tough, low-maintenance plant, so don't overwater and you should be fine.

Q: Could you please give me a little advice on a Hansen's cherry bush? I have had it for three or four years. It produced some fruit for me when it was young. Last year, it had hundreds of cherry blossoms all over it. However, in just a few days, all the blooms fell off. I live in Illinois. Can you tell me what may have gone wrong and what I can do to prevent this? I have had two people tell me two different things. One told me I need to get a bloom booster, while another said maybe the wind blew them off the bush. (e-mail reference)

A: I think what you are calling the Hansen cherry is a Prunus besseyi, also known as the western sand cherry. It is used a lot in shelterbelts and small wooded areas to attract small wildlife because of its very edible fruit. I don't know why you had a sudden loss of flowers, unless a cold snap occurred that caused them to abort. I suggest you try to be a little patient this spring to see what happens. If the blooms aren’t nipped by cold temperatures, then it should produce a mass of colorful fruit for you, until the birds find it!

Q: My wife and I are planning to plant a row of arborvitae for privacy. Our property slopes down to the area where we intend to plant the arborvitae. At the site, water collects from the natural flow of rainwater from other properties as it works its way to the sewer system. At times, the surface of the lawn is like walking on a wet sponge. Is the land too wet to plant the tree? If so, is there a tree that survives in a wet environment? (Tinley Park, Ill.)

A: If you plant the arborvitae, you'll have to raise the bed to keep the roots from sitting in water for any length of time. About the only plant I can think of you might want to plant is the upright bald cyprus. The species is a beautiful, stately tree that would be too big for your intentions, but perhaps the upright form can work. It is a deciduous conifer, which means it drops foliage with winter's arrival, but leafs out beautifully every spring. It would give you summer privacy at least. If you want to stay with arborvitae, the other suggestion I would make is to do some drain tile installation before planting to carry off the accumulated water. A good landscape design or contracting firm should be able to do that for you.

Q: Can I "top off" my river birches? How should it be done? Is July the best time? I live in New Jersey. (e-mail reference)

A: Topping a birch or any tree is the second worst thing you can do to it. The worst is to trim it at ground level. Birches are subject to a quick decline from topping, so please don't do it! Hire someone who is a registered member of the International Society of Arboriculture. Go to for additional information and help with locating someone who will do justice to your tree, but not murder it. In your part of the country, prune anytime after the leaves fully open, but don't wait until August to do it because the pruning wounds might not heal in time before winter sets in.

Q: I have a devil's ivy that I took from my mom, so it's more than a few years old. I was wondering if there's a possibility of reducing the size of the roots. I’d like to cut one-third of the roots off and then repot. The plant is healthy (a bit spindly), but is on the brink of outgrowing its large pot. I really want to add some new growth clippings to the root-crowded pot. (e-mail reference)

A: There is no reason why your devil's ivy shouldn't be able to tolerate a root pruning. Root reduction often is done to keep plants from going into larger and larger pots, which at some point can be a physical challenge to handle.

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) 231-8161,
Editor:Rich Mattern, (701) 231-6136,
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