April 3, 2003

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I have a diffenbachia that I received as a gift about a year ago. I divided and transplanted it into a larger pot shortly after receiving it. I have it in my office in a north window. Lately, I've been noticing that the new leaves are very small. Does it need more light or fertilizer? Also, I wanted to share with you that I had an amaryllis that bloomed at Christmas and then bloomed again for Valentines Day. Both times it was absolutely gorgeous! (Mandan, N.D.)

A: The diffenbachia is developing leaf size in relation to the environment it is in. I wouldn't push the fertilizer too much, but would suggest trying to locate more light for it, and as long as there is active growth taking place, keep adding small levels of fertilizer about once a month. Congratulations on your Amaryllis doing a double bloom! That is indeed unusual and enjoyable. Expect a long "recovery" now that all that energy has been expended. It may be a couple of years before you see it bloom again.

Q: I put some African violet stems in water a month ago. Now they have roots about a half inch long. What is the best way to transfer them to potting soil? (Brookings S.D.)

A: Very carefully as water developed roots tend to be a little more brittle than those developed in an artificial media like perlite, vermiculite, or peat moss. I would get some African violet potting soil, pre-moisten it, and then carefully place the newly rooted cutting into the soil. Water it in well to gently settle the soil around the roots.

Q: The front of my lawn is shielded by what I am told are arborvitae. I live along a major road so they hide my view of the traffic and cut down the noise. I got a local tree trimmer to give me an estimate for trimming them into shape. I was surprised when he said that he wouldn't do it! He says he'd kill sections of the tree or he wouldn't be able to shape them enough. He said that arborvitae only likes to be trimmed in the sections that are growing. Is this true? (E-mail reference)

A: I am glad to hear about honest tree trimmers whenever I can. There are too many individuals out there with chain saws and pickup trucks who incorrectly call themselves by that name. The beauty of arborvitae plants is that they need little pruning. They should never be cut back beyond their green leaves. A bare spot created by pruning is a bare spot forever and your tree trimmer knew that. Good for him!

Q: My spider plant has been a little neglected. It needs repotting and now has lost leaves near the base of the stem. It has long necks or stems and is growing over the edge of the pot. The plant is several years old so I'm wondering if I should break off the stem at some point and stick it in a cup of water to re-root. There are some nodules on the stem so I think it would re-root. Then, with the bare stem and the roots remaining in the pot, would they grow some new green shoots?

I'm afraid that if I repot the current plant intact, it won't look any more attractive because it will have long bare stems from the soil surface to the first green leaves. Any advice? (E-mail reference)

A: The spider plant can be propagated that way, in addition to rooting some of the spiderettes it produces.

Q: I have had this jade plant for a few years. It has always been healthy. Recently the stems began to flop and we noticed some little gnat-type bugs (fruit flies?) flying around the plant. I used an old trick I learned which calls for sprinkling some tobacco from a cigarette on the soil with the idea that the pestiscides should kill whatever bug it is. But after doing some reading, I realized that the problem was probably due to us placing the plant on the floor where it wasn't getting enough light. We put it back up in line with the window. It is still flopping and losing leaves and entire stems. On top of that, I just noticed today that there is some type of mold or fungus growing on top of the soil. It is bright yellow and specked in some spots and more formed in other areas. What can I do to save this plant? (E-mail reference)

A: It is probably too late based on your description. The mold you see on top is a saprophyte that is feeding on organic matter in the potting soil. From what you have told me, I would say that the problem was two fold: too much water and not enough light. Try allowing it to dry out completely and then watering it. That may rescue the plant from it's impending doom. If it does, that will go down as one small miracle in your book of remembrance!

Q: I love sweet peas but have been unable to grow them. This year I intend to plant them on the southeast side of my house with a trellis behind them. The soil is heavily amended with peat moss and manure. The seed packets always say to plant early, but how early is early for western North Dakota? (E-mail reference)

A: Soak the seeds first in tepid water, that is as pure and as low in salt as possible, overnight or 24 hours. Then plant when the soil can be worked and the frost is out of the ground. They are pretty tolerant of spring cold snaps.

Q: I have a friend who doesn't like all the apples that develop on his crab apple tree. Is there a spray of some kind which will deter the growth of these apples? (E-mail reference)

A: There are none that I could recommend with any degree of confidence. There are sprays that claim to control fruit set but they are variable in performance due to timing and cultivar differences.

Q: I have a healthy schefflera that is getting taller and wider by the week. Although I would eventually like it to be tall, I need to keep it short for now so that if will fit on a stand away from a young child. I would also like to keep it a little narrower than the way it’s growing now. Would you give me some pruning tips. Will this be a constant job or can it be trained? (E-mail reference)

A: Pruning a Schefflera to maintain size is a little tricky, although I am sure there is somebody in the world who will read this and offer a solution! You need to prune back to a joint or go about a quarter inch above where the palmately compound leaves arise from a stem. That will tend to keep the plant to size.

Q: I have three healthy peony plants in close proximity. Last year they did exceptionally well with many large white blossoms. But, when it came time to take a few in the house, I noticed they were infested with tiny black bugs which scattered all over the house. Needless to say my wife refused to have the sweet smelling blooms in the house. What can I do to prevent a repeat performance this year without harming the ants which I understand are necessary for healthy blooms? (Jamestown, N.D.)

A: Go ahead and spray or dip them into a solution of insecticidal soap before bringing them inside and don't worry about the ants. Old myths die hard. The ant/peony relationship is one that should have died a long time ago. While there is definitely an association between the two living organisms, it turns out that the ants need or like the peony flowers while the flowers don't need the ants. Peony flower buds are covered with tiny extra-floral nectaries which are special glands that produce a sweet nectar along the outside edges of the scales that cover the developing buds. Ants will devour this sweet concoction and even drive off insects that may wish to nibble on the buds but their feeding has nothing to do with the buds opening or not. As to what the tiny black bugs might be, your guess would be as good as mine at this point.

Q: Every year we end up with a lot of potato bugs on our potato plants. Is there anything we can add to the soil before planting and cultivating? (Edgeley, N.D.)

A: The best procedure is to not plant potatoes or any other member of the family such as eggplant, pepper or tomatoes in the same location. Next, see if you can get Bt enhanced potato seeds to plant. This is a biological control agent that is bred into potatoes and has proven to be quite resistant to the Colorado potato beetle.

Q: I live in an apartment building which has a community room that is quite warm. The temperature is kept at about 75 degrees. We have two Christmas cactuses which seem to be thriving. The problem is that they seldom bloom. Could it be too warm for them? They are kept in front of a south window so they get lots of sunshine. Can you tell me how to care for them to make them bloom? (Warren, Minn.)

A: It is likely too warm and the plants probably don't get enough darkness hours to set flower buds. You should move them to a cooler location about the end of September and cover them each night to keep all light out for at least 12 ½ hours. For example, covering them at suppertime around 6 p.m. and uncovering them at breakfast around 7 a.m. will give the plants enough darkness to set flower buds in about six to eight weeks. It would be best if they could be kept in a north or east window.

Q: Last week I checked my calla bulbs and found that they are beginning to grow. They have about one inch of new growth but seem to be quite dry. Should I pot them without water and leave them in the dark or should I just leave them as is? Because planting time is so far off, I'm thinking that the bulbs will wither and die. I also have two water lilies that are showing new growth and wonder if I should put them in water near the grow light? (Lisbon, N.D.)

A: Don't argue with the forces of nature. If they are showing signs of new growth, they are ready to be potted. Keep them watered and in adequate light until you are ready to move them outdoors this spring. Do likewise with your water lilies.

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