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

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I have been given three varieties of lilac trees in planters. One is a yellow variety with almost no stalk, but it does have long, bushy limbs. The second plant is a taller lilac that has the typical lilac tree shape. The third is a white lilac that is in the largest container (old wooden barrel cut in half) and has the typical lilac shape. Having been in planters for more than two years and then planted in my yard, do you think these trees will flower next spring? The woman who gave me the lilacs says they didn't flower a lot. I'm hoping it’s because of the small containers inhibiting growth. I've planted them in an area that does not get all-day sun, but definitely does from noon to evening. Also, is the yellow tree a Chinese variety? Is that why it has more of a bushy look than a typical lilac tree? Any tips on how to encourage flowering next spring would be appreciated. (e-mail reference)

A: Lilac flowers are developed on this year's growth. Generally, the lack of sufficient flowering is due to the plant not getting enough sunlight or too much nitrogen fertilizer. Flowering (reproductive cycle) is an energy-consuming activity. In order for the plant to come into flower, the plant requires a good storehouse of energy that is developed by a generous green leaf canopy. As to variety identification, I'm afraid that you will have to get a local expert to assist you with that. I am unable to do so from your descriptions. I probably couldn’t even do it looking at photos because the range of lilac varieties is extensive and indigenous to specific locations.

Q: I planted a bloodleaf maple tree. It does not seem to have grown a bit and I am not sure it is happy in its present location. Please tell me the best soil conditions and amounts of sun it needs to make it vibrant. I've been talking to it all summer long, but to no avail! (Smithtown, N.Y.)

A: This cultivar of Japanese maple never will be a fast grower. All I can tell you is that it needs full sun and moist soil that is high in organic matter. With your location, this tree species should be as common as popcorn in a movie theater and can be grown easily and beautifully. Keep talking to it. I guarantee you won't get a sassy answer.

Q: I have a nice river birch. It has three healthy sections and I have cared for it well. However, it has grown quite large and seems to be top-heavy, but not about to fall or anything. Your advice in the past has been to prune only when necessary. Does this mean that the tree's health will not be jeopardized by size or weight? If I did want to reduce its width so it won’t interfere with my deck or an adjacent pear tree, is there anything special I should know about the process? (e-mail reference)

A: I would suggest getting a professional International Society of Arboriculture certified arborist to intelligently and thoughtfully remove limbs that have the potential to break in high winds or during heavy snow loads. Make sure the arborist or company is not a “hat-racker” with the pruning equipment. Check credentials and ask for references before turning anyone loose on your tree. If you decide to trim on your own, don't leave any stubs and try not to remove any more than necessary. It seems that once a person gets into pruning, he or she fails to stop before it is too late!

Q: Jamestown has a number of weeping birches that appear to be dying this year including mine in our front yard. It has been losing a number of its branches this fall and the leaves are more brown than green. The tree has been steadily thinning at the top and the thinning is proceeding down into the center part of the tree. The tree's diameter is about 24 inches. We inoculate the tree for birch beetles every spring. I thoroughly water the tree during dry times in the spring, summer and fall. I fertilize the tree in the fall. I'm wondering if an iron treatment and a pH test might be beneficial. Also, I wonder if a mycorrhiza treatment might help. The tree is a landmark in our part of the neighborhood and we are as attached to it as Winston Churchill was to his. (Jamestown, N.D.)

A: Try to get a hold of Vern Quam, Jamestown city forester. He is very knowledgeable about trees and may be able to give you some on-site advice about your tree. It sounds like you are doing everything you should or could be doing. I can't recommend any treatments, such as mycorrhiza or iron, just to say you did something! Something in the environmental surroundings may have changed that could be contributing to the decline. You want to get this problem addressed as quickly as possible. Vern's phone number is (701) 252-5900.

Q: My young crimson maple apparently has borers, which has resulted in half of the bark peeling away at the base. Its leaves are OK, but only partly green. Will the bark heal itself in a few years? I have been watering it three times per week and had an arborist inject a root enhancer into it. (e-mail reference)

A: If you did not have the tree treated with a systemic insecticide to kill off the borers, no root enhancer in the world will make a difference. If the tree did receive treatment and the borer activity has stopped, the old wounds eventually will heal. I also question the wisdom of watering it so much. The tree is closing down the food-producing cycle of summer, so it shouldn't need as much water as it would during the summer months. I would suggest just a weekly soaking.

Q: I wondering about an ivy or vine that grows along many fences and other areas in the Fargo area. It has leaves that turn reddish-purple in color in the late summer and fall. When is the best time to plant or transplant it? Do you know the name of what I am writing about? (Fargo, N.D.)

A: This probably is woodbine (Virginia creeper). You can plant it anytime it is on sale at local nurseries. Woodbine has no trouble becoming established.

Q: I have six Boston ferns that I bought to hang on the porch during the summer months. They have gotten so large and beautiful that I can’t bring myself to toss them. The problem is they are too large to bring in the house. I want to hang them in my heated basement in front of the windows and put them out again next year. How do I get them to last? Should I cut them back or leave them alone? (e-mail reference)

A: Hang in there. Boston ferns can be kept inside and survive the long winter months if given proper care. However, there are some things you should know about these plants. When brought inside to weather the long, cold months of winter, Boston ferns don't always continue growing and thriving as they did outdoors. More often than not, they begin shedding leaves not long after they're brought inside. Dried leaves accumulate on the floor and create an ongoing mess. It's for this reason that many people shy away from growing Boston ferns. After buying and losing one Boston fern, some aren't willing to give it another try. Boston ferns require lots of light. Place the plant near a window that receives plenty of indirect sunshine. A bright east- or west-facing window is an ideal location. They can endure dimly lit locations, but they won't flourish and grow. If natural lighting isn't possible, then use plant lights that can be directed at them. Boston ferns prefer daytime temperatures that range from 65 to 75 degrees. Evening temperatures should be a little cooler. Temperatures ranging between 55 and 65 are ideal. Place your plant in a cooler location of the home or in a room where heat vents can be closed if the recommended evening temperatures are too hot. Also, keep in mind that areas closer to the ceiling are warmer than lower levels. If your Boston fern hangs near the ceiling, check the temperature and adjust it if necessary. Otherwise, consider placing the plant on a sturdy plant stand or table. As for humidity, place the plants in a saucer or pan that can hold water. This water should be distilled or melted snow because household water is usually chlorinated, which causes some problems with this plant species. During the winter, allow the surface of the soil to become a little dry before watering. When new fronds begin to appear, begin watering more often. Generally, you'll notice the appearance of new growth as the end of winter approaches. Briefly, move them in before cold weather arrives, cut them back somewhat to make them easier to handle, expect fronds to drop and the plants to look somewhat ratty during the long winter months. With perseverance, they will come out of the winter in fair shape and be ready to grace your porch again next summer.

Q: I have a Christmas cactus that is at least 70 years old. It belonged to my mother and grandmother. The plant is in its original ceramic container that does not have drainage holes. It is healthy and full, but I’ve noticed that the pot is starting to break apart. I am quite concerned about what to do at this point. Apparently, the plant likes being root bound. How do I transplant it without killing it? The plant means a great deal to me because of its age and history. I would very much appreciate any advice you could offer. Some have suggested leaving the plant in the original container, but putting it in a larger container. I read your column faithfully and find it interesting and helpful. (e-mail reference)

A: First things first, as the saying goes. Take some cuttings and get them rooted before you attempt to repot the plant. If the unthinkable happens to the mother plant, there will be survivors to carry on. Next, get a container about the same size, but with drainage holes. With a little shaving of the soil and roots, move it into the new pot. Give it some water and the plant should be OK. If you keep moving it into a larger container, you will get to the point of not being able to move it. While thinking of the plant, think of your back as well. Thanks for being a faithful reader!

Q: I recently bought a large croton for outside enjoyment. I now am wondering about the procedures necessary for bringing it inside. I was going to add some black dirt. Does it need fertilizer during the winter months? (Minneapolis, Minn.)

A: I suggest a complete repotting using fresh, pasteurized potting soil. To keep the unique coloration, add a plant light or two on a 12-hour cycle. Little fertilizer is needed during the winter months. When spring comes around and new growth is starting to be evident, give it a shot of general-purpose houseplant fertilizer.

Q: How can I start a plum tree from seed? (e-mail reference)

A: Take the pit and plant it where you want the tree to grow. Plant the pit about 4 to 6 inches deep. It will go through the winter months and sprout for you next spring, assuming the seed is viable.

Q: I am wondering about my cherry tomatoes. Every year, the tomatoes seem to split open on the vine or after I pick them. I would guess this happens to 50 percent or more of the tomatoes. Do you have any advice on how to keep them from doing this? I don't think I get the same brand or type of tomatoes each year. If you know of a variety that doesn't do that, maybe you can tell me what it is. (e-mail reference)

A: It has to do with water availability and the timing of picking the tomatoes. If the water supply is inconsistent, such as dry and then a good soaking, the sudden surge of water into the fruit will split the skin. Also, pick the tomatoes just before they get that deep, red color we all like. Then let the tomatoes ripen on your kitchen counter and you should not have too many splits.

Q: What is your advice concerning aerating lawns at this time of year? I haven't power raked for many years and mulch the clippings when I mow. I feel that my yard is pretty compacted. Also, should I cut our perennial flowers down in the fall? (e-mail reference)

A: Get the aeration done this weekend if possible. Wait to cut the perennials back until after a killing frost. However, you can leave them until next spring. I prefer the fall cutting rather than spring because the soil is usually too wet and cold to get in there and do it in the spring. Also in the spring, some plants are starting to break dormancy, so one has to exercise a little care when pruning. I like to set the mower high and run it right over all the perennial plantings. I never have suffered any losses or problems with that approach.

NDSU Agriculture Communication

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