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Ron Smith answers reader's questions about the world of plants, trees and gardens.

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I have two ash and two maple trees in my yard. The trees have edging around them. The inside area of the edging is filled with wood chips. There was fabric placed on the ground before the wood chips were put in. I cleaned the area out and found that the fabric is wrapped around the trunk. Should this have been done? The trees have a split in the trunk about 5 inches above the fabric. (e-mail reference)

A: The fabric is not needed and can be the source of problems as the tree matures. Remove the fabric and replace the wood chip mulch, but keep the mulch about 4 inches away from the trunk.

Q: I have a calamondin plant that my daughter got at Disneyworld when she was very young. She is now 44! It was a houseplant for many years in Pennsylvania. After I moved to Florida eight years ago, I planted it in my backyard that gets full sun. It has been thriving. In the past few years, new shoots have grown out of the ground around the base of the tree. I thought they were an intrusive weed and started cutting them down. Now I think they are probably volunteers from fruit left on the ground because I discovered they are bearing a few oranges that appear identical to the originals. Interestingly, the new shoots are very spiny, with many long and dangerous thorns growing from the main stem. What is happening here? The original plant has no discernible thorns. Can it be the old issue of seeds grown from a hybrid producing unpredictable results? (e-mail reference)

A: The juvenile growth of citrus trees is thorny. The thorns will disappear as the tree matures.

Q: I acquired a jade plant and have been scouring the Web for information on how to take care of it. What type of pot do jade plants prefer? Do jade plants like a deep or shallow pot? Should the pot be wide or narrow? The plant I took home is in a 7- by 5-inch pot. It seems like a very small pot for such a large plant. What are your thoughts? (e-mail reference)

A: Jade can be grown in any container, but I recommend a deep, wide, clay pot that drains freely. I say that for the simple reason that houseplants, jade in particular, tend to get overwatered. Containers of this configuration and material tend to be more forgiving of this little human nature shortcoming.

Q: We dug and replanted our iris plant two years ago. However, it has not bloomed since then. What is the problem? (e-mail reference)

A: You could have planted it too deeply or in too much shade.

Q: A client called wondering what effect road dust can have on trees. A row of burr oak trees that are heavy with scoria dust along a county road are dying. Is there any connection? (e-mail reference)

A: There is a very direct connection. Sunlight blocked by the dust covering the leaves will reduce photosynthesis dramatically. Any toxins in the scoria dust also may be leaching into the root zone.

Q: We moved into a house in Fargo a few years ago. We are finally ready to work on our landscaping. I have many questions since my wife and I are inexperienced gardeners. The house has a lilac bush in the east yard along a fence that marks the property line. I want to plant something along the fence to make it more attractive, but I am afraid more lilac bushes would look wild and out of control because they really aren’t hedges. I thought Juneberries might work as a hedge. If I remember right from growing up on the farm, they are woody and dense compared to lilacs, so the Juneberries should be more trimmable. Will Juneberries exist in peace with a lilac? (e-mail reference)

A: The two plants will coexist in peace and harmony, so enjoy! The birds also will love you!

Q: I have a pear tree that had a lot of blooms on it, so tiny pears are starting to grow. However, some of the pears are turning black and falling off. Is this because there were a lot of little pears in a cluster or is it some kind of disease? (e-mail reference)

A: Could be some of both. I suggest picking off some of the pears to give them a little more breathing room. Get a fruit tree fungicide to prevent the spread of any disease.

Q: We have an established weeping willow in our horse pasture. The horses have decided to munch on it and have removed a large section of bark. What steps should I take to preserve this tree? (e-mail reference)

A: The best advice is to cut the torn bark back to where it is attached to the trunk. It will heal naturally without any help. Keep your munching horses away from the tree by erecting an exclusion fence or by spraying Liquid Fence or Plantskydd on the parts they might eat.

Q: I have a large candytuft in my garden. I love it. I want to propagate some of it to other areas. Can I cut a stem to create a root? As you probably know, it grows rather large and the base is the only way to get to the existing roots. (e-mail reference)

A: Stem cuttings root easily or you can divide the crown. Good luck and enjoy!

Q: I was listening to you discuss crab and quack grass on talk radio about a week ago. Can you tell me the difference between the two and how I can treat either of them in my lawn? Is there some chemical treatment I should be using? I put Prevent fertilizer down about a week ago, but I don't think that is sufficient. You also mentioned we should mulch our clematis. Can you recommend what mulch to use? (e-mail reference)

A: Crabgrass can be controlled with a pre-emergent herbicide. Herbicides work best if not used in combination with fertilizer. Quack grass has no selective control that is available in North Dakota. Sorry, I was mistaken in what I said over the radio. Mulch around the clematis needs to be organic, such as bark or sphagnum peat moss.

Q: I want to spray a flowering crab tree to prevent disease. The product says to spray during the early bud stage. The buds came out two days ago. When is early bud and can I still spray the tree? (e-mail reference)

A: If you mean the buds opened and are showing leaves, then don’t use the spray because foliar damage will occur.

Q: An area of my lawn once had pea rock on it. Most of it has been removed, but there is still quite a bit of it embedded in the grass. Will pea rock harm the grass or significantly inhibit its growth? Is complete removal recommended? If so, how do you suggest going about removing embedded pea rock? (e-mail reference)

A: If the pea rock doesn’t cause a mowing problem, then leave it alone and mow high, which is something that should be done anyway. Getting rid of the pea rock will require using a power rake to loosen it up and then hand raking or shoveling to get it picked up.

Q: I purchased a calla lily about three weeks ago. The plant was in the bathroom of my house that gets little light as was recommended. I watered it when it seemed dry. One of the blooms (flower and stem) fell off. It looked as if it had been broken off. I noticed that it had some kind of mush at the end. I decided to move it to a window so the plant would get more light and fresh air. However, the flowers and stems still are falling off. I also noticed a white/yellowish mush in the soil. What could be wrong with my calla lily and do you have any suggestions? Part of the plant seems to be fine, but I’m afraid that it will turn to mush as well. (e-mail reference)

A: I have some guesses. The problem could be caused by overwatering, poor drainage or using nonsterile or pasteurized soil. I suggest getting it out of the container. Repot in a container that drains well and use fresh soil that is pasteurized.

Q: I'm having trouble getting grass to grow under my evergreens. I've planted grass seed specifically designed for shaded areas and I've tried to remove as many evergreen needles as I can. Is there a product on the market that would neutralize the acid from the needles? I don't even know what kind of acid is present in the needles, but I do remember a simple chemistry rule that an alkali can neutralize an acid. (e-mail reference)

A: Usually, this not a problem. Try using some limestone (finely ground). Sprinkle the limestone under the tree and carefully rake it in. Use only shade-tolerant grass, such as a creeping red fescue.

Q: My wife and I are wondering how far to space techney arborvitae when using it as a form of privacy fence or hedge. We also are wondering if they will survive in a windy, unprotected area. Can techney survive our cold winters? (Jamestown, N.D.)

A: They could survive if they were purchased from a local source. If you planted them about 6 to 8 inches apart, they will grow into a nice, dense fence or hedge in just a few years, but it depends on the size of the plants you started with.

Q: We live in a new development area in south Fargo. We are looking for shrubs we can plant in the front of the house to add some curb appeal. The front looks kind of boring right now. Last summer, we planted a Princess Kay plum tree (I’m really excited that it made it through the winter), three globe arborvitaes and two rose glow barberry bushes in a bed along the sidewalk. That bed will be continued to a bed where we want to plant the new shrubs. What do you recommend that will be large in height to fill a space from the ground to the window? I would like something that will add character during the winter as well. Is there a shrub that I can buy that is the right size and can prune to stay that way or will we need to plant something smaller and wait a few years before the space is filled in? Unfortunately, I am a slave to my generation and enjoy instant gratification. (e-mail reference)

A: Excitement is something that is individually defined. What turns someone on may not another. I like the Annabelle hydrangeas because they are easy to grow and have a nice, long blooming season in our area. Another good one is the red twigged dogwood. It takes a little more work, but is worth the effort. A combination of the two shrubs will make a good visual impression. The combination would almost give you the instant gratification your generation craves.

Q: I have a young oak tree. Last fall, I noticed round balls or gauls attached to the ends of the branches. Each little ball had a hole in one side and it looked like some bug or worm had grown and left. One had a little, white worm inside. How can I keep these pests from using my tree? I want to keep the tree, but the balls are unsightly, especially in the winter when the leaves are gone. Also, does this harm the tree? (e-mail reference)

A: This is one of the characteristics of an oak tree. The gauls do not hurt the tree and spraying for control is not recommended. A good arborist can take out the galled branches selectively without disfiguring the tree.

Q: It says everywhere I read that you prune apple trees before they leaf out in the spring. What is the definition of leaf out? Does that mean fully leafed out or can you prune with buds on the trees? I have a fully mature tree that produces lots of apples, but needs some thinning. (e-mail reference)

A: Go for it today if you can or as soon as possible. During bud expansion is OK, but once they begin opening, they become more vulnerable to disease problems. It isn't cast in stone, but dormant pruning in early spring is always better.

Q: I have a perennial wildflower garden that I want to kill and make into a vegetable garden. Is there something else other than Roundup I could use to kill the flowers? I want to use something more natural that wouldn't affect the vegetables in any way (we eat mostly organic at our house). Thank you for your help! (e-mail reference)

A: Cover them with a light-proof tarp, black plastic or newspapers piled on thick for the growing season. That usually does the trick.

Q: I am a novice at growing tomato plants, so I don’t understand what “before fruit set can take place” means. What is a fruit set? How do I recognize what fruit set is? This probably sounds like a stupid question and the answer probably is simple. I’m thinking it means a cluster of tomatoes on a branch. Is that correct? (e-mail reference)

A: Not a stupid question at all! Fruit set is what takes place after the flowers are fertilized. Your interpretation is perfectly correct.

Q: I have raspberry canes in my garden that keep spreading. No matter how I cut them down every year, they just keep coming back and multiplying. They have pushed themselves up in the cracks between the flags in the path and are invading all my borders. How do I get rid of the canes? (e-mail reference)

A: Spray the canes with Roundup when they leaf out and be persistent for a year. Digging them out also will do the trick because their roots don't go that deep, so relatively speaking, individual plants are easily removed.

Q: We had a new well put in the front yard and now there is an area covered with a layer of fine sand. I intend on putting a flowerbed in the same area. My husband thinks there might be chemicals in the sand. Can I put the flowerbed on top of the sand? I plan on using black dirt, some peat moss and maybe Miracle-Gro with the peat. (e-mail reference)

A: I wonder what chemicals your husband thinks might be in the sand. Yes, go ahead and plant your flowerbed on top of the sand with the addition of soil and peat moss.

Q: I'm hoping you can help me. I have a few apple trees that I planted from bare-root stock two weeks ago. When I got them, a couple had what looked like the beginnings of leaves that had wilted. Now these trees are covered in grey-green fuzz. It comes off easily when I scrape it with my fingernail, but it doesn't seem like a healthy thing. I've attached two very blurry pictures to help illustrate the problem. I'm guessing it's some sort of mildew. I've read that mildew only attacks foliage and it likes warm and moist weather, but we've had nothing but cold weather since the trees were planted. Any advice would be much appreciated. (e-mail reference)

A: I don't think you have anything to worry about. What I think you are seeing is the wax that bare-root trees are sometimes dipped into to help prevent desiccation. I would give it a couple of weeks more before you start worrying about these trees. From what I can tell by your photos, it looks like good-quality nursery stock.

Q: We have two cottonwood trees in what is to be a new vegetable garden. However, it is very tempting to plant a beautiful area of shade-loving plants around the trees. I have found mixed information on how to do that. We were thinking of adding a narrow mound of enriched soil compost (all organic) about 2 feet wide and approximately 2 feet from the trunk. Is there any issue to prevent us from doing this? If not, are there any guidelines to be aware of? (e-mail reference)

A: It is done all the time with no dire consequences, so enjoy.

Q: I have a flowering crab tree that is about 15 to 20 years old. I need to move it or lose it. How long does a flowering crab tree live and when would be the best time to move it? I want to make sure it would be worth the expense of moving. It is a healthy and very beautiful tree. (e-mail reference)

A: You might be close to the useful end of this tree's life or it may live on for decades. Moving a tree this age will be expensive, as well as stressful on the tree. The tree could die after being moved. If it were up to me, I wouldn't go to the expense. You can plant another tree at a much lower cost. A new tree also will have a better chance of surviving.

Q: I purchased an autumn purple tree in April that did not have leaves at the time. Will the tree produce leaves this year? Maybe I am impatient, but the only thing I see is that there are flowery blooms starting on a couple of the branches. (Pueblo West, Colo.)

A: You are being impatient. Cool your jets for a couple of weeks. If the leaves have not started to emerge by then, ask the nursery what your next move should be.

NDSU Agriculture Communication

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