November 6, 2003

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: As a creative person I want to come up with a rye, fescue or blue grass that has a color other than green or find some short native grasses that are already colored that can be planted with lawn grass. What I want to do is to create mosaics and patterns in lawns, sort of like painting a picture on your lawn. So far I've had no luck in finding anyone who has had success with this, nor have I found any short native grasses that are green, gold, red or even very dark green (almost black) that would work. There are various colored tall grasses but those are used for borders. Can you direct me to someone who has attempted to create colors in grass or perhaps short mowable colored grasses? (E-mail reference)

A: I have not heard of any mowable colored grasses. About the only thing you can attempt is to work with the different hues of green that the many cultivars of turfgrass provide. If you visit any land grant university where turfgrass research is carried on, you will be able to see the differences in the various shades of green. If I get wind of anything developing along your lines of interest, I will certainly let you know.

Q: We have three rose bushes that are doing well. Should they be cut down this fall or wait until spring? (Powers Lake, N.D.)

A: Cut them down now and cover generously with soil and leaves for winter protection.

Q: Is total removal of leaves best for a lawn or can they be mulched with a mulching lawn mower. The lawn area is on the north side of the house and the lawn is already showing stress from the trees shading the lawn area. (LaMoure, N.D.)

A: Total removal is almost impossible in North Dakota because of the winds shifting everything around. Remove what you can and mulch the rest in with your mower.

Q: We have a paper white birch that looks like it is dying. It is about 20 years old or more. The top half didn't develop leaves. The bottom half has leaves and looks healthy. Is there something we can do? By the way, we planted three trees to make it a clump birch. (Milnor, N.D.)

A: The birch is very likely suffering from bronze borer attack. I doubt that you can save it at this point. Once that pest gets started, it is just a question of time before the tree is completely destroyed and yours is about the right age for this to happen. Sorry!

Q: How can I protect my arborvitae from winter sunburn? (Dilworth, Minn.)

A: Spray the trees with Wilt Pruf before winter and before the air temperature drops below 40 F. Repeat during a winter thaw in January or February.

Q: I have a jade plant directly under a fluorescent light on my desk. It also gets indirect office window light. It is very healthy but now has air roots. Is this ok? (E-mail reference)

A: That simply shows that you have a very healthy, normal and happy plant. You are doing everything it needs to carry on a good life. Keep it up!

Q: My boss grew sweet potatoes and now wants to know how to keep them until next year to plant in the garden. Some say to start them around Christmas and then plant them outside in the spring. Is it possible to store them like potatoes then cut them up and plant them in the spring? Will they dry out if you store them in a cool dry place? (E-mail reference)

A: Sweet potatoes are more difficult to store than the typical white or Irish potato. They should be handled as little as possible to prevent damage and brought into storage and curing immediately after harvesting. They can be cured by holding the temperature at 85 F and 90 to 95 percent relative humidity for four to seven days. Curing helps heal cuts and other injuries during harvesting and handling. If these conditions cannot be followed, then curing will take longer and the possibility of decay and disease will develop. For storage and holding, the temperature should be reduced to 55 or 60 F. That is usually accomplished by venting with outside air. The humidity should be kept at the 85 to 90 percent level. Under these conditions, must cultivars will keep for four to seven months. Expect a weight loss of 2 to 6 percent during curing and storage. I’m a non expert in this matter so all of the above information was pulled from USDA Agriculture Handbook 66 and other sources.

Q: I have an aloe plant that is forming brown spots on it and drying up on the ends. Could I be underwatering it? (E-mail reference)

A: Sounds like you might be, but poor drainage and salt build up can result in the same symptoms.

Q: When is the best time of year to trim arborvitae globes to keep them from growing out of shape? (E-mail reference)

A: The best time to prune arborvitaes is just before new growth begins in the late spring but do not cut it back beyond the green foliage. Doing so will condemn that spot to be bare forever. This is perhaps one instance where an electric hedge shear could be put to good use!

Q: When is the best time to prune cottonwoods, Austrian pine and pinon? (E-mail reference)

A: In the early spring before new growth and after the candle growths have elongated and the needles have just begun to pull away.

Q: I would appreciate information on how to crack open walnuts. We have a lot of them this year. They are great in breads and cookies. (Big Stone City, S.D.)

A: Try putting them in the freezer for about 72 hours. Freezing the walnuts should crack them open. If they are not cracked completely, take a screwdriver and twist along the crack that has developed. This will take some twisting and holding with a vise or something similar, but it can be done. I think I have seen black walnut "crackers" in a mail order catalog somewhere.

Q: I have a Norfolk Island pine that is, it appears, two or three pines growing together in one pot. It was purchased that way a few years ago. The plant is ready to be moved to a larger container. Would this be a good time to separate the pines that are growing together? If it turns out that there is only one plant with multiple trunks coming up from under the soil, is it a matter of personal preference whether I leave them or clip them off, or would clipping off the smaller ones hurt the remaining larger one? Finally, if the smaller trunks are removed (either by separation or by clipping), should I still go ahead and move the main trunk into a larger container, or just repot it in the same container? (E-mail reference)

A: Norfolk Island pines don’t do well if things don't go exactly right. You have separate plants, which is a common sales practice with florists and nurseries. I would suggest separating them carefully and planting each one in its own container. Try to put them in a location where the conditions are as close to identical to the original as possible. With luck and if the plants are "in the mood" to being moved, you will have multiple Norfolk Island pines to enjoy well into the future.

Q: I have a 25 to 30-year-old Christmas cactus that has developed root rot (no spores visible). I have lost three major trunk branches and am starting to loose another. I have repotted in new soil and have been very careful with watering but it doesn’t seem to be working. I read about digging it up and cutting out all the dead material from the trunk then replanting. Will it work? How about chemicals? (E-mail reference)

A: The plant should re-root if you remove all of the decay and replant it in a sterile media. It doesn’t need chemicals. The single segments should root quite easily, almost like weeds. Be sure you have them properly oriented, stick the distal end into the soil or media for rooting, not the apical end.

Q: My fiddle fig leaf has been with me for many years. I have fought off spider mites with alcohol and cotton but lately brown spots have developed on the leaves and a lot of leaves have fallen off. What is the cause and what can I do about it? (E-mail reference)

A: I suspect scale insects. Look carefully on the stems near their tips and along toward the main trunk. These pests will appear as little bumps that may be the same color as the bark. If the infestation is light (not likely from your description) you can rub them off with a swab soaked in alcohol. If the infestation is heavy, then you are better off getting rid of the plant.

Do you have a gardening or houseplant question? Write to Hortiscope, Box 5051, NDSU Extension Service, Fargo, ND 58105 or e-mail to Ron Smith at ronsmith@ndsuext.nodak.edu. Note to e-mail correspondents: please identify your location (city and state) for most accurate recommendations.

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Source: Ron Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu