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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: I’ve had a ficus tree for more than 20 years. It has done OK during that time, depending on whether it was getting enough light and water. However, something has happened to the roots. It doesn't seem to have much in the way of roots and it falls over without support. I have repotted, but the soil doesn't seem to compact. I haven't noticed any pests, but haven't had time to dig into the soil. Have you ever seen this problem? What should I look for and what would you recommend I do? Oddly, the plant does not really seem affected by this condition. (e-mail reference)

A: The soil might be lacking in sufficient organic matter and/or phosphorus. It probably isn't worth the effort to get a soil test made for a houseplant, so I would suggest getting a fertilizer that is high in the last two numbers on the label (phosphorus and potassium) and low in the first one (nitrogen). Use the fertilizer monthly to see if the plant will develop a more extensive root system.

Q: I live in the Tampa area of Florida. About a year ago, I purchased a Christmas cactus that was in bloom. Soon all of the unopened buds fell off. I assumed the change in environment caused the problem. It has been very healthy since and adding new joints. About a month ago, one of the stalks began to go limp and now the veins up the center of the joints are purple. There also are roots growing at each joint of the stalk. The planter sits about a foot from a north window and about 5 feet from a west window. It is watered once a week. The ailing stalk is facing the north window but does not sit in any kind of air current. Should I cut out the ailing stalk and enjoy the remaining healthy ones? How can I make sure it blooms at Christmas? (e-mail reference)

A: You can try luck at getting it to bloom, which is what Al Schneiter, our department chair, does (and his always blooms!) or you can follow the methods found on my Web site at Basically, you want to start giving it 12.5 to more than 13 hours of complete darkness every day. Once the flower buds are visible, you can leave it in the normal light of your home. As for the sick stalk, cut it out. Aerial roots are not uncommon on these plants in nature, especially in areas with high humidity. It is not as common in households where the humidity is low, especially when the central heating system kicks on in winter.

Q: I use milorganite in my garden beds and lawn and at the garden center where I work. I have found it makes a good deer deterrent at the garden center if I start applying it early in the spring. I also find a benefit from the iron it provides in both areas, plus it's low in nitrogen. I do not use it in my vegetable garden or around my fruit trees because of the possibility it may contain metal. What are your thoughts about milorganite? What is another example of a biosolid? Also, I have been told that if I use mycorrhizae, I need to be careful using other products, such as Miracle-Gro (not my favorite, either) or weed and bug-type chemicals, because they will break down in the soil and destroy the fungi. What are your thoughts on mycorrhizae? Several years ago, I participated in a simple soil test at a garden center. The soil analyst told me my soil had a very high pH level and suggested I start adding gypsum to my lawn in spring and fall. I did this religiously for several years and started noticing a lot of improvement. The biggest difference was with winterkill in the areas that my dogs catered to. However, I have started hearing that gypsum is no longer recommended and that it doesn't do anything for the pH level. Is the sulfur in gypsum elemental sulfur? If not, what type of product has elemental sulfur? I add lots of organic matter to my planting beds, so I wouldn't know how much the gypsum has helped. However, I do feel that gypsum has helped my lawn a lot. What are your thoughts on gypsum for clay soil that tends to have a higher PH? (e-mail reference)

A: Milorganite is considered a biosolid. It is not safe to use on edible vegetable crops because of the heavy metals it and others may contain, especially cadmium. I know there are other biosolids on the market, but cannot name them for you. Using milorganite or any other feasible biosolid on lawns and nonfruit bearing trees is considered acceptable, but like vermiculite with asbestos, it should be handled with caution because of the possible contaminants. I was using both products with almost reckless abandon, thinking they were safe, until I learned otherwise. I'm glad I've grown old enough to get wiser about such things. Being a skeptic about what is being "raved" about in the marketplace is gaining more license with me. This leads me to the great hoax of mycorrhizae additions to the soil. If one were to believe the hype surrounding the products on the market, it would be thought that our soil and plants are starving for what is in the container. In reality, mycorrhizae occur in all but the most sterile soil, such as acid mine washes. In that possible case, the addition of commercial stuff may make a difference in establishing plants. All other soils have sufficient spores to aid the plant. The plant then supports the beneficial fungus. The natural ones are good for mining nutrients, such as phosphorus, which sometimes are in limited in quantity in the soil. No one knows how many different mycorrhizae exist in nature. Since they are somewhat host specific, commercial preparations are necessarily high in their varied selection. There is a very good chance that the spores your particular plant needs are not present in the commercial mix at all. These spores also are sensitive to environmental changes, such as temperature extremes. The spores may be alive when they leave the place of origin, but may be stored in inhospitable conditions on the way, which kills them. Dead spores are not going to do the plant any good. Generally, the soils are nutrient-rich enough throughout the upper Midwest that the addition of commercial spores is a total waste of time and money. Simply adding compost or peat moss to the garden soil on an annual basis will keep an adequate supply of these spores available to aid plants in growing, if they need any help. Gypsum falls right behind mycorrhizal spores for deluding the public. A mix of calcium sulfate supplies a very powerful action in calcium and an equally powerful union with the sulfate ion. It does not change soil pH. It is most useful if the soil is deficient in either of the elements that make it up. It will not be useful for improving permeability due to problems with soil texture, compaction, hardpans, claypans or high water tables. Any results you thought you saw from the addition of gypsum were most likely the result of the organic matter you added.

Q: We recently cleared a bunch of dogwood bushes that were between some trees lining our front yard. There are many sticks still coming up that we would prefer to kill. How do you suggest we do this? Also, the hedge of dogwood on the other side of the trees is something we want to keep, but would like it to fill out more. Should we cut it back now or in the spring and how far back should we cut it? We would like it to have a nice, full even-topped hedge look year after year. (e-mail reference)

A: The dogwood volunteers can be killed off with a spray of RTU Roundup next spring or this fall if they are still in leaf and the tissue is still green. For the hedge you want, leave everything alone this fall. Before the foliage emerges in early spring, cut everything down with a hedge clipper or chain saw. If the plants were alive this year, they will come back with a vengeance next year, so you should have the nice, dense hedge you want!

Q: I came across your e-mail address while researching my question. I live in Missouri and would like to plant some corn for the deer and turkey where I hunt. However, the place I want to plant the corn is heavily forested. Is there any type of corn that will grow with limited sunlight? I only want the corn to attract the deer and turkeys, so maximum yield is not a priority. Am I better off going with a different crop or is there a variety that would work in these conditions? Thanks. (e-mail reference)

A: Corn will not grow and produce in shade. Corn needs as much sunlight and heat as possible! You might be better off this year getting some field corn from a local farmer and scattering the cobs around where you intend to hunt. I guarantee you it will attract the game you want!

Q: I planted nine wintergreen and three nigra trees for use as a privacy screen. Is there anything that I need to do at this point to prepare the trees for winter? I live in central Pennsylvania. Any recommendations would be greatly appreciated. (e-mail reference)

A: At this point, let them go into winter dormancy with moisture stored in their foliage. Don't use an anti-transpirant because it often causes the foliage to discolor. Also, do not fertilize. Some folks wrap a coarse burlap cloth around the plants to protect them from wind burn. Others don't bother without the trees suffering detrimental effects.

Q: My spider plant has never produced babies until the last six months. I attribute it to the fact that a year ago I moved to a house that has lots of windows and skylights. About two months ago, I noticed that some of the leaves were turning brown. Some leaves only turned brown at the tips, but on some, the entire leaves were dying. I repotted the plant because I thought it was getting too big for the pot that it was in. It is not a free-draining pot, but neither was the pot that I had it in before. I also put some rocks in the bottom of the pot because I did not have enough soil to fill the pot. Other than the leaves with brown tips and the dead leaves that I have removed, the plant looks very healthy and two new strands of babies have sprouted. What should I do? (e-mail reference)

A: The brown tips reflect salts in the water and/or soil. It is not a problem worth worrying about. Go to my site at and read through the material on spider plant culture.

Q: Is it better to transplant rhubarb during the spring or fall? Thanks. (e-mail reference)

A: Better in the spring, especially in North Dakota!

Q: During the past three years, I have had 22 Black Hills spruce transplanted using a truck spade. During the last two weeks, three out of six I planted last spring have needles turning light green to brownish through different areas of the trees. Are they going to die and spread the problem to the other trees? I have watered them well. My soil is very sandy. (Wisconsin)

A: What you describe is a bad sign. Once this starts, it usually doesn't reverse itself. Generally, spaded trees are planted at the right depth, so that usually isn’t a problem. Often, if the trees have not been root-pruned during the preceding years, too much of the root may have been removed during the digging operation. I don't think there is much you can do except hope they recover with the tender loving care you are providing. I suggest getting ahold of the tree spade operator to see if he has any suggestions to help the trees recover. It would be in his interest to help you out if possible.

Q: I've hunted all over the Web, but still cannot find what I'd like to know about the care of a pineapple crown. I got one started from the information you e-mailed me and it is starting new growth. Do I need to fertilize it? If so, what fertilizer formula do I need? Do I use full or half-strength? Can I remove the dead leaves from the plant or should I let Mother Nature take its course? (e-mail reference)

A: The growing crowns usually take pretty good care of themselves once started. As long as it is growing, a half-strength of a high P and K fertilizer would benefit the plant. Don't try to force it in the dead of winter when no growth is evident. Also, try to keep it in the sunniest window and provide additional light from a plant light for 12-plus hours a day to keep it healthy and making its own food. Any dead leaves can be removed by using a pruner, knife or simply tugging them off. However, if the leaves don't tug, cut them. Enjoy!

Q: My friend mentioned to me something weird about spider plants. She says the plants clean the air of older houses that have underground cellars of a certain harsh chemical or poison gas that has settled in the house. She's a real estate agent, so I can see where she derived her knowledge. I understand that all plants produce oxygen. Have you ever heard of something like this? I'd really like to know because I can't stand spider plants. Also, what's the best way to start a bougainvillea from a cutting? A few of my friends own this plant, but it is tough to find where I am stationed. Can I root it in water or should I try it with a hormone root stimulator? What are the odds of success? (e-mail reference)

A: There are plenty of plants, such as Chinese evergreen, ficus, dracaena, several species of palms, ferns, aloe, croton and many more, that can help clean the air of pollutants. Get "How to Grow Fresh Air" by B.C. Wolverton. It probably will have to be special-ordered from a bookstore. Wolverton wrote about research that was carried out by NASA for the space program to help purify the environment and provide oxygen for the astronauts during prolonged space missions. In other words, just about any plant you can grow indoors will contribute to the quality of the indoor air. For your propagation, go to and download what is specific to your interest or the whole publication. Bougainvillea easily root from cuttings.

Q: I’ve had a dieffenbachia for more than four months. It seems to be growing naturally and has no particular problems, except that its leaves point downward. This also happens to the new leaves. I have started to worry about my plant. Is there anything I can do? (e-mail reference)

A: Find something else to worry about. Some plants have leaves that point down, while others don't. You shouldn't try to correct this with more water or fertilizer because such action would kill the plant.

Q: I enjoy reading your advice. After a year of drought in Duluth, the bark on our silver maple is falling off. Can you tell us what's happening? Is there a remedy? (e-mail reference)

A: With a mature tree, it is a natural occurrence in most cases. Unless there is evidence of borer or bark beetle activity under the peeling bark, you have nothing to worry about. I would think giving the tree a couple of good soakings before winter would be a good thing to help it through the stress of drought.

Q: An individual called about losing his chokecherry shelter belt plantings. He also stated that another individual has lost all his trees. In talking with the individual, the planting is 15 to 20 years old. This does not sound good to me. Is there a tree disease that could be causing this problem? Perhaps this is an accumulation of too many dry years followed by a year with reasonable moisture. (e-mail reference)

A: It could be the infamous X-disease. There is a publication from Ohio State University ( that describes the disease on peaches and nectarines, which are cousins of the chokecherry. The problem also could be the bone-dry years taking their toll.

Q: I live on a lake and am curious if there are any other methods to kill ground ivy. Trimec has an ingredient that is toxic to aquatic invertebrates. I have heard that lye soap works. (e-mail reference)

A: Go to for a publication that lists many alternatives to Trimec. You might need to go to a licensed commercial applicator to get this done. I'm sorry, but I have no information on the effectiveness of lye soap in controlling this weed.

NDSU Agriculture Communication

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