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Ron Smith answers questions about plants, trees and gardens.

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I purchased a piece of land last year with three silver birch trees on it. The largest is about 30 feet tall and had a low branch removed many years ago. The inside of the stub rotted and was filled with water, mud and worms! I cleaned it out and cut a thin slot in the stub to let the water drain and prevent it from building up again. The hollow in the stub is about a foot deep and 3 inches in diameter. At the moment, the hollow is dry, but I will have to keep an eye on it to make sure it doesn't fill up with fallen leaves and start to collect water again. Have I done enough to save the tree or is it a lost cause? (e-mail reference)

A: What you have done is good, but you could do more. Cut the stub back to one-fourth inch from the trunk. That will facilitate healing properly and keep this from happening again. A hollow like that is a magnet for the small wildlife in the area. If you cut it back to fresh wood, the problem should be solved. If you want to see some basic graphics of what I am talking about, our publication "Pruning Trees and Shrubs" is available for downloading at

Q: When I was cleaning up my flowerbeds, I came across quite a bit of moss growing on the soil. In several places, it was quite dense. Does it do any harm to leave it or should I be scraping it off? Will it die during the winter? Last winter, I lost six healthy, low-growing junipers in front of my house. I have replaced them and am wondering if there is anything I should do before cold weather sets in. We have had plenty of rain, so they definitely won't go into the winter dry. (e-mail reference)

A: Do absolutely nothing with the junipers. However, I’m assuming you purchased them locally and planted them properly. As for the moss, this is an indication of poor air infiltration into the soil and the soil remaining wet too long. While the moss will not hurt the plants, it is an indication of poor water movement into and through the soil. There are two things you can do with moss. You can break it up and till it into the soil. You can cut it off and make a nice moss garden with it (boulders, flowering succulents) or sell it to a person that makes terrariums for a living. When I used to teach terrarium workshops back in the good old days, I would have welcomed extra moss. If your moss problem persists, get the pH of the soil checked. It might be that you need some lime.

Q: I dug up all of my iris plants a couple of weeks ago and divided them. However, I have not gotten them replanted yet. Our soil is saturated and very muddy! What can I do with the bulbs/tubers? I don’t want to lose them. (Hawley, Minn.)

A: Shake as much of the soil off the plants as you reasonably can. Cut the tops back to about 3- inch stubs. Discard any tubers that are soft or rotten. Dust the others with a sulfur powder or Funginex if the sulfur is not available. Place them in paper bags and store them in a cool location, such as your basement. Check the bulbs monthly through the winter and discard any that have begun to rot. Replant at your earliest convenience next spring.

Q: I have a large maple tree in my front yard. I had twice as many leaves last year as I did this year. This has me concerned that the tree may be dying. This summer, we did have a bad infestation of little, red, biting bugs that destroyed many of the other plants in my yard before moving out of the area. The tree still looked full through the summer, but I definitely can tell that there are fewer leaves to deal with this fall. (e-mail reference)

A: If the tree was otherwise healthy, you have nothing to worry about. The numbers of leaves can vary from year to year. It depends a lot on what the weather conditions were for that growing season. If crown dieback starts to develop, that would be a concern.

Q: How likely are raspberries and strawberries to survive in a raised bed in the Horace area? The beds are about 12 inches tall. I have mulched the beds with leaves. Is there anything else that might help? (Horace, N.D.)

A: The plants very likely will survive if you planted hardy cultivars.

Q: I planted my maple tree in the lawn because it was outgrowing its pot. It is not as healthy as it was before the replant. I was wondering if lawn watering or fertilizing could be the problem. It is still leafs out, but not as much as before. I could stop fertilizing by the tree if needed. (e-mail reference)

A: As I have said many times before, I wish people would tell me where they are writing from or where they are referring to when they ask me plant questions. It makes it easier for me to provide more accurate answers. If you transplanted it while it was still in leaf this past summer, then likely it is transplant shock the tree is going through. Another potential problem is that the tree was planted too deeply, which happens often. Another possibility is the tree going from an ideal soil in the container to something less than ideal in the soil. If you live anywhere in the Upper Midwest (North or South Dakota, western Minnesota or eastern Montana) the soil type, especially the pH, typically would be too high to support a healthy, growing Japanese maple. Overwatering from a lawn sprinkler will drive the air from the root area and limit the amount of growth the tree can provide. Japanese maples thrive in organically rich soil that is moist, but not soggy. They thrive in high-humidity areas, such as San Francisco and along the eastern coastal states. Generally, they don't need fertilizing, just loamy, highly organic soil to produce a beautiful plant.

Q: This spring, I planted 19 Norway spruce trees in paper fiber pots. The grower I bought them from told me it was OK to leave them in the pots. However, I’m worried that the trees might become root-bound as they get older. If this is the case, is there anything I can do now to prevent this from happening? The trees seem to be doing well. They have good growth and color. (e-mail reference)

A: The trees should be OK. Those fiber pots have been used in landscape situations for many years. The pots are sturdy enough, but then break down as the soil moisture and microbes begin to work on them after planting. If they were in tarpaper pots, you would have a valid concern because they take too long to disintegrate. If they appear to be doing OK, leave them alone and enjoy your trees.

Q: My husband and I purchased our first home in October of last year. We have a gorgeous crimson king maple on our front lawn. We've enjoyed the shade and beauty of this large tree, along with the huge, plum-colored leaves. To our shock, the tree changed color this year! The leaves turned a beautiful yellow. Our neighbors also were amazed because they've never seen this tree change color. Is this a bizarre occurrence? Is it possible for them to change color? I tried to do some searching on the Internet and read that the leaves on these trees do not change color. We have taken some pictures as a keepsake because it looks more beautiful with its yellow leaves! We are so curious as to hear what this may be! (upstate New York)

A: Leaf color changes because of weather changes are not uncommon. However, I would have to agree that it is unusual for your tree to change color. Pigmentation in the foliage is dependent on so many things. The normal fall color of Norway maples, which the crimson king is a cultivar of, is yellow. However, this is a rare occurrence by a crimson king, so enjoy it for all it is worth!

Q: I have a question about a clump paper birch tree we planted about five years ago. The tree is doing great. However, we are concerned about how close it is to our house. Do we have to move this tree because of its potentially damaging root system? We are hoping to trim only a few branches when they come too close to the house or windows. We would appreciate your insight and help because we want to do what is best for the tree. If we need to move it, we feel now may be the best time to do so. We live in Ontario, Canada. (e-mail reference)

A: Thank you for telling me where you live. I can tell you that the tree is in no way a threat to your foundation. I have a huge cutleaf weeping birch in my front yard that is more than 22 years old. It is 8 feet from the foundation, sidewalk and driveway. We have not had a single hint of any problem with the roots doing any damage. For the most part, roots will follow the path of least resistance to where the water, air and nutrients are. Leave this beautiful tree where it is. When it comes time for pruning, have it done by a professional who knows that birch trees need little pruning to keep them in bounds or looking good.

Q: I bought a spider plant from a nursery. It was outside in the rain and chilly weather at the nursery. I know the soil has to dry out, but it won’t, so I’m afraid of root rot. Some of the leaf tips are brown and others are dead from the stem up. The babies are fine so far. Should I repot it in new soil? (e-mail reference)

A: Repot the plant as soon as possible in a container with good drainage. You also might try potting some of the babies just in case the main plant doesn't make it.

Q: My pear tree has bloomed well every year since I planted it five years ago. However, it never bears fruit. Can you tell me what could be wrong? (e-mail reference)

A: Apparently there is no pollinator, such as another pear species, nearby. Also, there could be a shortage of pollinating insects in your area. Most likely, you need another pear to get some fruit. An ornamental pear will work if there is no interest in having two fruit-bearing pear trees in your yard.

Q: We have a river birch that is in need of pruning its lower limbs. The leaves are green, but starting to turn yellow. The weather in this part of the country has not turned cold yet, but it is coming. Would now be a good time to prune the bottom limbs? (Fort Mill, S.C.)

A: Pruning now would not give the pruning wound an opportunity to heal until spring. If you do it now, expect to experience relatively heavy sap flow from the pruning wound next spring. This will not hurt the tree, but it does look unsightly for a few weeks until the tree leafs out. Generally, the best time to prune birch trees and other bleeders is after they have leafed out. This minimizes sap flow from the wound and facilitates faster healing of the cut. However, as an old forestry professor once told me, prune anytime there is a need to do so and when the pruning tools are sharp. Sometimes, that's just what you have to do!

Q: I have seven blooms on my amaryllis. How long will it take for the blooms to flower? I hope I will have flowers for Thanksgiving. (e-mail reference)

A: If you can keep the plant on the cool side, it will delay flowering or hold the flower longer. Higher temperatures will push them along faster. I'd suggest keeping the plant in as cool a location as possible (above 50 degrees, but not more than 65 degrees) to hold the blooms back for Thanksgiving.

Q: Why won't my lipstick plant bloom? (e-mail reference)

A: The lipstick plant or vine is one of the more difficult plants to grow as a houseplant, let alone getting it to come into bloom. The secret seems to be plenty of bright light, but not direct sunlight. It also needs lots of humidity and warm temperatures. Don't overfertilize the plant. During the upcoming winter months, keep the plant on the cool side (55 to 65 degrees) and back off significantly on the watering. In my humble opinion, this or any other plant that has to be fussed over excessively to bring it into flower isn't worth the time and effort. Either tolerate it as a foliage plant and hope that it will flower under the conditions you are willing to provide or dump it.

NDSU Agriculture Communication

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