March 6, 2003

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: What kind of soil do you need to grow medium to large-sized onions in the northeastern part of South Dakota? I’m only able to grow small onions. I’d appreciate an educated answer on how I can improve on these plants. My garden spot is raised and gets plenty of water and sunshine. (E-mail reference)

A: Onions grow best on sandy or loose soil. Being shallow-rooted, they are sensitive to any nutrient deficiencies in the upper six inches of soil. In the absence of a soil test, you might want to add about 10 pounds of 5-10-5 to every 1,000 square feet of gardening area. The looseness of the soil can be increased with generous amounts of sphagnum peat moss being worked into the upper six to nine inches of soil prior to planting. Finally, don't allow the bulbs to become moisture stressed during the growing season. They need an even delivery of water.

Q: I have acquired a schefflera umbrella tree. It seems to be growing just fine but it often loses its leaves. It grows well at the top but the leaves that are further down the trunk grow to a large size then fall off. Is there a way that I can promote growth down the trunk or is this the way it’s supposed to grow? There is also a lot of growth toward the bottom of the pot. I'm not sure if these are individual plants or it’s supposed to grow that way. Is it possible for me to take anything off the bottom and replant to start a new plant? (E-mail reference)

A: No, that is not the way it is supposed to grow. The leaf loss is probably reflective of insufficient light to maintain the older leaves. The new growth you see coming from the base is a result of the plant attempting to readapt to the low light situation. There are a couple of things you can do; air layer, repot or both. I will forward you my "Home Propagation Techniques," a bulletin which should help you rescue your plant and carry out the air-layering technique.

Q: I have a 20-year-old jade plant. Sometimes its leaves turn patchy brown and fall off after they shrivel up and become sparkly silver. The silver color does not rub off. Some of the leaves are large while some are very small when it happens. It also has clusters of air roots around the end-tip branches. The air roots are not all smooth and some have little fuzzy growths on the sides. It has been growing in a clay pot for a number of years. The pot appears to have rust on it around the upper outer edge. The pot is eight inches high and 14 inches across. The plant base is softball size and the plant is about two and a half feet tall. Is the pot too small? It is not root bound at this point. I have been root pruning in order to keep the bonzai effect. It was transplanted 18 months ago. There are no parasites visible. Some leaves appear to be pitted, some dry up from the outside edges into the stem and some sprout in odd shapes. The problem started about six years ago but has become worse in the last year to the point where it is no longer gaining in size. The bark is grey except for a few end branches yet it is firm with no signs of softening. (E-mail reference)

A: The symptoms you describe baffle me. You have been successfully growing it for 20 years but now in the last six years these problems gradually appeared. Is this plant in a location where only you have access to it? I ask because you sound like you know what you are doing and obviously have a good track record of successful maintenance. I suspect some minor mischief. Is there anybody that is "bugged" about your bonsai jade? Has anything changed such as temperature, light exposure, fertilization, watering schedule, water source, or anything else that may be affecting the plant? It almost sounds like a minor herbicide problem such as drift from outside, contamination from a container used for watering or seepage into a well water source. I would suggest changing some routines. Start by getting a new container or completely clean the one you have. I recommend new potting soil despite your fastidious care in root pruning to keep the plant from becoming pot-bound. If possible, try and root some of the leaves or healthy, firm stems to perpetuate the plant so you don’t lose the plant if it comes down to that.

Q: I have a two-story-tall evergreen tree growing near my house. I want to remove it because I worry the roots may penetrate the foundation of my home. Is my fear valid? I have heard horror stories about roots cracking foundations. Once I cut down and remove the tree, will the roots continue to grow into the foundation? I must admit I am leaning toward removing the tree if there is even a chance of major damage. (E-mail reference)

A: Trees are good if they are providing a service, but when they become a liability, they should be removed. I would worry more about the aerial part of the evergreen than the root system. Roots will grow only where they can and need a balance of air and water to do so. Unless the foundation of the house has cracks and leaks, it will not grow into the foundation while the tree is whole or after it is cut down. I suggest getting a competent, certified arborist out to examine and remove the tree and stump completely if the tree is too close to the house and would cause property or bodily damage if it should become a windfall casualty. Be sure the individual has liability insurance and ask for references.

Q: I have a very big problem with my crown of thorns plant. I've had this plant for many years but all of the sudden it wouldn’t bloom anymore. It then started to look sick so I cut off a stem and placed it in water. The main plant died not long after that and looked totally dry. The stems were deformed and twisted. I focused on the stem in the water and it was rooting so I thought it was fine. Then my boyfriend’s sister threw it in the garbage because there was no water. I retrieved it from the garbage and placed it in water again. I thought planting it in soil would help it but it looks like it's dying. I've put this plant through hell and I don't know what to do. (E-mail reference)

A: Try to get your rooted cutting in potting soil as soon as possible and do it carefully. Roots formed in water are usually more brittle than those formed in sand or other rooting media. It’s hard to say what killed your crown of thorns, but it could be overwatering. That is a common occurrence during the winter months. This is a plant that needs a sunny window, moderate watering from spring to autumn and sparse watering in between. Always let the media dry between watering. It should be repotted every other year. Lack of flowering is nothing to be concerned about. Plants expend quite a bit of energy during the reproductive cycle and often need a rest period for an extended time to rebuild carbohydrate reserves to get into the reproductive cycle again.

Q: I have seen no mention of spider plant seeds. I have grown many spider plants from seed. When the flowers die, you may have a three-sided seed pod. Let the seed pod go from brown to black and then peel the skin off. You can then plant the seeds in soil. I plant them in egg cartons. Before long, you will have little spider plants growing. (E-mail reference)

A: Thank you and you are right. To make sure that readers understand, the spider plant you are talking about is the cleome spp., not the chlorophytum spp. That's a problem with common names. The cleome spider plant will actually self-seed right in the garden, but I agree with you, it is more fun to collect the seed and start them yourself.

Q: The leaves on my indoor yucca tree are very dusty. The dust sticks to the leaves and I can't get it all off with plain water. I know there are commercial plant-leaf cleaners that I can buy but is there a home concoction that I can make that will safely clean the leaves? (E-mail reference)

A: I would suggest using insecticidal soap. It will not hurt your plant or you and it should clean it up quite nicely while getting rid of any hiding varmints that may be lurking in the leaf axils thinking they had found their nirvana!

Q: I recently acquired a mature jade plant and was hoping to shape it up a bit. I read through many of the other questions and found lots of helpful information on care but not too much on pruning. Is there much you can do with a mature jade plant? It’s about one foot high and very bushy. I was hoping to make it look more like a tree and less like a shrub. (E-mail reference)

A: There is no problem with pruning your jade into a tree form. The important thing is the pruning tool. Use either a razor blade or a scalpel type knife so plant tissue is not bruised. Stem any excessive sap flow with activated charcoal. Don't prune more than a third of the branch canopy at one time. Give the plant a few months to recoup in between pruning events. You might want to take some of the cuttings you remove and root them for new plants. Jade roots easily.

Remove a stem or leaf with a razor blade or sharp knife and root in 50/50 sand/peat, keeping the media damp.

Q: I bought an amaryllis in honor of my late Mom. It produced two flower stems. One stem produced three flowers while the second stem produced five flowers. The flowers have faded and so has the foliage. I removed the bulb from the soil and after cleaning it with warm water, found a bulblet on the corner bottom. Is it possible for me to cut this bulblet off to start a new plant for next year? The bulblet does not have roots attached to it. (E-mail reference)

A: You should have allowed the foliage to remain through the summer and then backed off on the watering to allow the foliage to die down. The foliage is the source of food for rebuilding the mother bulb and the bulblet you found. You can plant the bulblet and allow it to leaf out, going through the wet/dry cycle I just described. In about two years or so you should get a flower or two. If you haven't thrown away the mother bulb, replant it and get it to refoliate to build carbohydrate stores for future flowering.

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