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Ron Smith answers questions about plants, trees and gardens.

By Ron Smith, Horticulturist

NDSU Extension Service

Q: We have a Christmas cactus that had pink flowers. Now the cactus is in bloom, but the flowers are white. How does Christmas cactus change colors? (e-mail reference)

A: Good question! I really don't know what causes this to happen. I've speculated in the past that it could be a chimera (somatic mutation of some kind). However, the question comes up so often that I wonder if that is the cause for the color change. With some hydrangea species, the change from pink to blue is due to a change in the soil pH. It could be the same with the Christmas cactus. A water pH above 7 eventually would result in a pH change in the soil that might influence the flower color change. Sorry, these are all guesses, but it is the best I can come up with because I cannot find any cogent reference that would be able to explain the color change.

Q: I have a young maple tree. I noticed a small crack in the bark coming up from the base of the tree about four months ago. The crack is now becoming wider and it looks like tiny, brown ants are eating the bark. We have been told to put a fungicide on to treat for carpenter ants. So far, this hasn’t worked. Any suggestions as to what this might be and products to remedy this problem? Will this damage my tree permanently? (e-mail reference)

A: Carpenter ants go after dead or decaying wood, not living wood. Applying a fungicide is meant to kill a fungal disease, not insects. Ants can be controlled with direct sprays from any number of insecticides or you can use poison bait that the ants will take back to their nests to deliver a more complete kill. You need to determine or have someone who knows what he or she is talking about inspect the tree and give you advice. He or she should be able to tell you if there is a reasonable chance to save the tree. If I knew where you live, I might be able to give you stronger guidance in contacting someone.

Q: I’m going to plant a row of techny arborvitaes in full sun. I’ve read that they should be planted 3 1/2 feet apart to create a hedge. They will be planted within a retained area. Should they be planted at least that same distance from a wall? Also, the area is not filled yet, so I can add whatever soil mixture is best. Do you have any suggestions? (e-mail reference)

A: You should use a sandy loam-type of soil with generous amounts of sphagnum peat moss for good drainage. Before planting, make sure the retained area has good drainage or else you'll be creating an enclosed system where anaerobic problems for the roots will develop and kill the plants.

Q: I bought two Concord and two Catawba grape vines last spring. During the first year, the plants had green leaves, but didn't grow in size. We planted them in late June. The second year, the vines grew very well, but we still didn't develop grapes. Is this normal? Should we cut some of the leaves during the summer to allow fruit growth? I didn't prune the vines the first year because they didn't grow. Should I prune them this year? If so, how much and when? (Melrose, Mass.)

A: Impatience! The vines eventually will bear fruit. Sometimes it takes two to four years for them to do so. Give them a chance to become established as you are doing and without pruning. You probably will see some this year. Don't overfertilize or they will remain vegetative instead of bearing fruit. The University of Minnesota has one of the best publications on grape growing in the country for cold climates. You can find the publication at Good luck!

Q: I have two trees near my sump pump discharge that are not doing as well as the same type of trees on the opposite side of my yard. I diverted the discharge hose a year ago, but have yet to see a change. Should I be fertilizing the trees differently to correct any deficiencies? The trees are a sunset maple and an ornamental columnar pear. (e-mail reference)

A: Sump water discharge can be nasty stuff. It can be high in salts and other stuff that may seal the soil around the roots and otherwise be toxic to normal plant growth. I would suggest that you do two things. Get about a pint of soil from under the canopy of the tree that is free of any grass or other vegetation. Send the sample to the land-grant university in your state to have it tested. Next, contact a local International Society of Arboriculture certified arborist to aerate the soil around and under these trees. This should be done in the early spring. You could show the arborist the soil test results. If any amendments are called for, the arborist can include them during the visit.

Q: I have had a jade for years, but it never flowers. How do I get it to flower? (e-mail reference)

A: It will flower if you live long enough. Jade is considered a foliage plant, not a flowering one. If they do flower, it is a momentous occasion for the plant owner. Usually, photos are taken the same as if a new baby has come to the family. Enjoy the beauty of the jade for its form, character and handsome foliage. If it ever flowers, treat it as a pleasant surprise. If you do this, you'll have fewer frustrations.

Q: I have a question about tree planting. How far from a drain field can we plant evergreens or any other trees? What kind of evergreen tree do you suggest for this area (southeastern North Dakota)? What can you tell me about the larch evergreen tree that also is referred to as a tamarac tree? (e-mail reference)

A: The more distance away from the drain field, the better. Figure what the mature height of the tree should be and then plant the tree that distance from the drain field. As for evergreen choices, I'd say just about anything other than a blue spruce because there are too many already planted in North Dakota. The larch is not an evergreen, but a deciduous conifer. The tree has needle foliage like an evergreen, but drops them every fall. This gives them the advantage over other evergreen confers because they are not as subject to winter stress, foliar burn or desiccation. These beautiful trees have attractive, small cones and produce fresh growth every spring that doesn't hang around long enough to get beat up by Mother Nature. On the downside, it looks bare in winter, which people often mistake as being dead if they don't know they are deciduous conifers.

Q: We received a Colorado blue spruce seedling and need to find out how to take care of it. Where would I go for this information? (e-mail reference)

A: Assuming your soil has not frozen yet, get it planted in as full a sunlight location as possible. Be sure to account for the mature size this tree can grow to, which is 60-plus feet. Most people overlook that detail. Water it in and protect it with chicken wire this winter to keep the bunnies from getting to it. If your soil is supporting grass or weeds, you don't need to fertilize. Frequently water the tree next summer. Keep the soil moist, but not soggy. Put a ring of bark mulch (2 to 3 inches thick) around the seedling. Go out about 12 inches. Given this simple care, it should take hold and thrive. You didn't say how you got the seedling. Is it bare root or in a container? If it is bare root, do not allow the roots to dry out. In fact, keep the roots immersed in water until you plant it. If it is in a pot or container, try to plant it using as much of the container soil as possible.

Q: I planted 39 spruce trees this year. However, I’ve been given conflicting advice about how to plant a balled and burlap tree. I just spoke with a sales representative for a large nursery. He said that if you remove the cementlike dirt from a balled and burlap tree, the tree would die the next spring because exposing the roots to oxygen kills the tree. I've appreciated your Web site and your counsel. Do you concur with his advice? Put another way, how do you recommend planting a balled and burlap tree? (e-mail reference)

A: Very carefully, as you would with any tree. In this case, dig the hole deep enough so that the top of the ball is even with the surrounding soil, but make the planting hole four times wider than deep. Set the plant in the hole and then carefully cut away the twine. Carefully peel back the burlap, but leave it on the bottom of the hole. Backfill the hole with the native soil if it is halfway decent or with an improved soil mix that has the characteristics to create good drainage. Keep in mind how these plants grow in nature. They certainly are not pampered because the seed is dispersed by wind or wildlife. By chance alone, they survive in otherwise hostile environments to become beautiful trees. In other words, plant them the right way, water them in well and for the first couple of years after the planting, monitor their moisture status in the root area. Keep the plant damp, but never soggy. The advice given by the nursery sales representative was right on the money when he told you not to expose the roots to air. If the roots are dry, give them a good soaking prior to planting. If the soil is very dry, prewater the site prior to planting. The chances of success will improve dramatically if you follow these common-sense steps. Good luck and enjoy!

Q: I'm in zone 7 here in Georgia. A customer asked me to look at a Norway spruce that he'd like to transplant to a new property. It was planted in 1982. The tree has thick, full branches all the way to the ground. The tree appears to be healthy and thriving. However, there is a milky white sap oozing down the trunk, but not on any of the limbs. I could not find any damage that would indicate sapsuckers. I also could not see any borer damage. You responded to another question similar to this and suggested it might be cytospora. Could that be the case with this spruce tree? The concern is whether the tree is healthy enough to move or if the sap has stressed the tree. (Clermont, Ga.)

A: Something is causing the sap to ooze. It could be borers, bird damage or a weather-related problem, such as hail. It also could be that someone hit the tree with a rifle or shotgun. Cytospora canker occurs starting on the lower branches and gradually works up the branching system. You state that the tree appears healthy and full all the way down to the base, so I don't think the tree has cytospora fungus. I think it is from some type of physical injury. It should survive. You have a much nicer climate than we do, but our trees are moved and re-established up here successfully.

Q: I brought my poinsettia inside a few weeks ago and left it in the garage. It is now in the basement out of the cold weather. I’m hoping it will bloom again! How should I care for it? (Moorhead, Minn.)

A: Go to to find the answer to your question. The plant needs 12 to 13 hours of darkness every day, but not continuous darkness. This should be started around the first week in October to get it to come into bloom sometime around Christmas. If the plant is in continuous darkness, then I'm afraid the plant will be too weak to respond to any kind of treatment at this point. You might be better off throwing this plant away and looking for a fresh plant after Thanksgiving. Follow the directions in the publication. Sorry for the bad news.

Q: I’m wondering how to care for bougainvilleas through the winter months. I brought them inside and placed them in front of an eastern-facing window. One of them is growing some new flowers. (Norman, Okla.)

A: Treat the bougainvilleas the same as you would any other houseplant that is brought inside. Water sparingly, check at least weekly for insects or diseases and take corrective action immediately if there is a problem. Move the plants outside when the danger of frost has passed in your part of the country. Be sure they get as much light (natural and artificial) as possible.

NDSU Agriculture Communication

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