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Ron Smith answers reader's questions about the world of plants and gardening

By Ron Smith, Horticulturist

NDSU Extension Service

Q: When is it too late to plant arborvitae? I've heard they need a few months in the ground prior to the first frost. (Chicago, Ill.)

A: Nursery stock is available in containers or as balled and burlap plants. Both are ready for planting if the ground is not frozen. Now would be a good time to plant because it will give the roots time to get established so the plants will take off next spring with a nice flush of growth.

Q: I read your material on the care of ficus trees. There's a lot of good information there! I have two trees that are about 10 years old. We recently moved to a new house with less natural light. As expected, after a few weeks they started dropping leaves due to the different light conditions. I would like to prune them because they are too large in their new space. Should I wait to prune until they've adapted to their new environment or will pruning help them adapt? (e-mail reference)

A: Pruning will help them adapt, but don't overdo it. If there isn't enough light energy coming in to support the present foliage, the plant will drop its leaves until a balance is established.

Q: We have an autumn blaze maple tree that we would like to transplant for a second time because we feel that it isn’t growing to its potential in the spot that it is now (competing with two willow trees). What is the possibility of it surviving another transplant? Do we have to wait until the leaves have fallen off before we move it? Also, would a royal empress tree survive in our climate? I loved its beautiful purple flowers and have yet to find another tree that can compare and survive in Canada. (Calgary, Alberta)

A: You are better off to wait until a few good, hard frosts have shut the tree down. As for the royal empress, it isn't hardy in your area, which is just as well. I have seen it when I lived in the southern U.S. Other than the snapshot of beauty when it is in flower, it has nothing else going for it. You would end up hating it because it is messier than weeping willow trees!

Q: I am going to transplant 25 to 30 volunteer white and burr oak trees. I am wondering if there is a certain size tree and specific time of the year that works best for transplanting. Are there crucial factors to keep in mind? (e-mail reference)

A: Transplant in fall or early spring while the trees are dormant. Try to get as much of the root system as possible and don't allow the roots to dry out. Keep them wrapped in moist burlap until planting and get it done as soon as possible. Plant the smallest trees available because your chance of recovering all of the roots is increased and they will establish faster. Do not plant them any deeper than they were at the original site and water them well. Water completely no more than two or three times a week unless they are planted in pure sand. Protect them from nibblers, such as mice, rabbits, deer and moose, until they are established.

Q: I planted two packets of petunia seed in a raised flower box. The roof of the house is extended over it. I kept it moist, but never saw a plant come up until I looked out the window and saw a purple petunia blooming in November. It bloomed through the winter. It is still blooming 10 months later. I know it is unique, so I called several agencies in Nashville to see if they would be interested, but none were. I guess they thought I wasn't telling the truth. I planted some seed from the plant, but none came up. Does a petunia need cross-pollination to produce seed that will germinate? Can it be cross-pollinated from the same plant or does it need a different plant? It seems this petunia has the same qualities that the pansies have that live through the winter. If you can help me preserve this petunia, I'd surely appreciate it. (Nashville, Tenn.)

A: Your strange petunia likely is a wave petunia or one of the new, tough F1 hybrids. Believe it or not, wave petunias and a few others still were going strong well after several hard freezes here in North Dakota. The fact that it didn't produce any seedlings is because it has been bred to not do so or you might have sown the seed too deeply. Being one of the smallest seeds to work with, they get germinated in greenhouses on top of sterile media and covered with paper to keep the surface moist until germination.

Q: I ordered red worms that are used in composting table scraps or whatever. Are they safe to release in the environment or would they damage my garden and lawn? I started out with a few hundred, but now I have way too many. (e-mail reference)

A: That would depend somewhat on where you live. I suggest that you contact the company that sold you the worms for advice.

Q: I bought a juniper that I would like to plant close to the road near my driveway. The road gets heavily salted during the winter, so I'm wondering how the juniper will do with the salt. I live in Maine. (e-mail reference)

A: Probably not too well with the heavy salt unless you have good snow cover and the soil is well-drained.

Q: Two different people have informed us that when you collect rainwater from a roof in a galvanized stock tank and the tank should rust through the years, the rusty water will kill plants. One fellow feels that it may have killed two poplar trees. Another felt it killed the plants in his garden. Can you inform us if rusty water can be harmful to plants and trees? Can the material on the roof (tar) running into the tank be the problem? (Hebron, N.D.)

A: I know many people who collected water from roof runoff in all kinds of containers to water their garden and houseplants without ill effects. Unless there is something unique about your particular situation, I don't see that as a problem. You could get a student to set up a small science experiment to see if there is something in the water that is killing the plants. Get six corn and six tomato plants started in separate containers. Provide tap or drinking water to three corn and three tomato plants. Give the collected water to the rest of the plants. Keep everything else the same and observe how the plants grow. If the plants getting the collected water die, that is pretty good evidence that something on the roof or in the container is killing the plants.

Q: The chokecherries in Minnesota all seem to grow on trees, but in Montana the chokecherries I pick during July vacations grow on bushes. All the references on your Web site were for trees. The bushes are much easier to pick berries from than trees. Are these two different types or is the difference a climate thing? The Montana bushes are growing in the open in Dawson County, which is just across the border. (e-mail reference)

A: If you are sure the fruit you picked was chokecherry fruit, I would say the difference is in climate, which is not unusual.

Q: I planted my strawberries on May 1. They had a few blossoms and some small strawberries the first part of June. Since then, they have grown and put out lots of runners. Should I remove the runners? They haven't made any effort to bloom. I have them in a round bed and water them lightly every evening. (e-mail reference)

A: This is the normal pattern of growth for strawberries. You should have removed the blooms from the plants this spring to help get the roots established so they wouldn't put any energy into making berries this first year. What you can do is redirect the runners to attach where you want them and remove the rest. There is no need for nightly watering. In fact, it is a bad idea because you are setting up an environment for diseases to elevate. A once or twice a week good soaking is all that is needed unless there are weather extremes, such as temperatures in the 90s or higher with no rain.

Q: We have a red maple in our yard that is about 20 years old. This year we noticed a rather long crack on its trunk. I’ve also noticed that a few of the thicker branches have small cracks as well. I read on your Web site that trees that have these conditions usually show up on younger trees that have suffered frost cracks and it will happen until the tree has developed thicker “skin.” When is a tree considered older? Is our tree still young and does its condition sound like frost crack? We live in New England and had an unpredictable winter last year. (e-mail reference)

A: While frost cracks are more typical on younger trees, they can and do occur on older trees as well, especially if the weather goes through wide swings in temperature during a short period of time. Generally, they heal on their own without any further damage to the tree. I would advise monitoring the tree to be sure there is no decay or insects taking up residency.

Q: I have moved into a house with what I was told are river birch trees in the backyard. They have white bark. I noticed everything near the trees was getting a sticky substance on it. A friend said it is raining down from the birch trees. Is this normal? How can I control it or is it just something that the trees do? (e-mail reference)

A: The tree is either infested with aphids or spider mites. Get someone to inspect and possibly apply the appropriate pest control material. This is not normal.

Q: We live in northern Michigan and would love to grow some Canadian chokecherry trees, but the only types we can find do not produce fruit. They are called Canadian red select and Canadian cherry. Are these trees the same as those grown in North Dakota? My brother-in-law in Lisbon showed us his and called them Canadian chokecherry trees. (e-mail reference)

A: They are one and the same. Your brother-in-law is right and those trees in Michigan also should produce cherries.

Q: I have a question about our lawn. It appears to have a rust color. After you walk across it, your shoes get a rusty-colored dust on them. What could be wrong with the grass? Is there anything I should do to help it? (e-mail reference)

A: This is a rust fungus, but it won't kill your grass. In most cases, the grass outgrows the pathogen. You can help your grass somewhat with a light fertilization and collecting the clippings as long as the rust is present. While it is common on lawns that have been established within the last year, some cultivars of bluegrass are more susceptible to it than others. With the change in weather coming up in a few weeks, the rust should disappear.

Q: Our son moved to a house in Fargo that has a lumpy lawn. The neighbor next door claims the previous owners had problems with earthworms. Do you have any suggestions on how to get rid of the worms? (e-mail reference)

A: Have the lawn treated for grubs. The treatment should reduce the earthworm population by 25 percent to 30 percent. He also can rent a ballast roller. Fill it halfway with water and roll the lawn to make the surface smoother. This should be done about 24 hours after a good rain event or a thorough irrigation cycle.

NDSU Agriculture Communication

Source:Ron Smith, (701) 231-8161,
Editor:Rich Mattern, (701) 231-6136,
Prairie Fare: Prairie Fare: De-stress with Gardening  (2019-05-23)  According to researchers, gardening can be beneficial for mental, physical and social health.  FULL STORY
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