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

By Ron Smith, Horticulturist

NDSU Extension Service

Q: Yesterday I received some amaryllis bulbs using a delivery service. Even though the box was clearly marked do not freeze, the box was left outside my door. Needless to say, the bulbs froze. Are the bulbs salvageable? It pains me to throw any type of plant away. (e-mail reference)

A: The bulbs are not salvageable if they were frozen. All the bulbs will do is rot. Sorry!

Q: I've read your Web page with interest and hope that you can help me bring my Christmas cactus back to health. It is a few years old and in about a 3-inch pot. It bloomed in previous years, but I think I was a little lax with it last year. We had building work done, so it was basically untouched and unwatered for a couple of months and in a very dusty environment. After reading your Web page, I probably overwater it. I give it a reasonable soaking once a week, even though the soil on top is dry by that time and the pot feels light. I watered it as normal (for me) during the autumn. However, a lot of leaves and whole branch structures became limp and have fallen off. The plant is quite bushy and only has three branches left. The base of each branch is hard and woody and some of the remaining leaves are flaccid. I repotted it a few months ago and dusted the leaves. It does seem to have recovered somewhat, but I'm still concerned. It was situated in a warm, east-facing room that lost direct sunlight around 11a.m. It now sits on a windowsill in a south-facing room where I often work until midnight. From reading your Web page, I think I should move it out of this room to one with a more regular pattern of dark periods. Other than doing that and a better watering regimen, are there any other things I can do to reinvigorate my plant? Should I take leaves off to grow new plants and leave the distressed core of this plant to rest in peace? Is there still hope? (e-mail reference)

A: You not only read my Web page, but my thoughts as well. I recommend that you take some leaves and attempt to root them in case the mother plant decides to call it quits. These are amazingly tough plants that have fooled a lot of people with their miraculous recovery. Don't get impatient and attempt to correct past neglect by overwatering now. When you think it needs watering, it won't hurt to wait another day.

Q: We are having a large, cottonless cottonwood cut down and the stump left in place. What can I use to help keep suckers from springing up? Will I need to wait awhile to plant things around it? If so, how long do I need to wait before replanting? Do cottonwoods deplete the soil of nutrients that I will need to replace? I want to replant the area with fruit trees or berry vines. Any recommendations on the species I should plant? (Denver, Colo.)

A: If the cottonwood was alive when it was taken down, you can expect to deal with suckers sprouting up for a couple of years. You will be driven crazy trying to control all of this growth. You can plant around the stump immediately. As far as nutrient depletion goes, the cottonwood is not any worse than any other tree, shrub or vine. Normal fertilization practices, such as using a 10-10-10 fertilizer, will take care of any needs. For advice on fruit trees in the Denver area, I would suggest you contact my horticultural counterpart at the Colorado State University Extension Service. Go to to find the proper contact. Other than price, is there any reason why you are leaving the stump behind?

Q: I have started tomato plants (cherry, rutger and celebrity) indoors using fluorescent lighting. The plants are the healthiest that I have ever seen. Bloom clusters have formed, but they don't smell the same as those grown outdoors or even in my sister’s greenhouse. Just curious why the smell would be lacking and will it change the flavor of the fruit? (e-mail reference)

A: Why the plants don't have the smell of the other plants is something I don't know. Perhaps a reader of this column will be able to tell both of us the reason why. The plants may get the familiar odor when the bloom clusters open and the pollen ripens, but I don't know for sure.

Q: I have a healthy African violet plant that has about seven rows of leaf spread. I would like to repot the plant. Would it be advisable to trim back some of the rows of leaves before repotting? (e-mail reference)

A: African violets can grow like weeds sometimes. Yes, go ahead and make clean cuts using clean snips or a knife. You also can root your cuttings if you wish.

Q: Back in 1963 when I was 7, I went with my dad to buy a birch tree for our front yard. I helped him plant it. My father died when I was 13, but the tree is still alive in the front yard of my old house. How can I start another tree from the original? Would that mean getting seeds from the tree somehow or cutting a small branch off? (e-mail reference)

A: Propagation methods vary depending on the species. Growing trees from cuttings is possible, but difficult. As with all birches, timing is critical. The best time is to take cuttings just before end bud set in midsummer, which varies from one region of the country to the other. Bud set is noted when the terminal bud on a branch goes from green to a brownish, dark red. It is just before this turning takes place that the chance for success of rooting the cuttings is greatest. I suggest taking cuttings around the middle of July or when you see the end bud darken and turn hard. You will have to dip the cuttings in a rooting hormone. After that, put the cuttings in a cool, moist and shaded area. Success varies from species to species. The weeping birch cultivar is the easiest. For seed propagation, collect ripe, brown, woody catkins (from its resemblance to a cat's tail) in a bag to keep from losing any seeds. Spread the seeds out to dry for several weeks. Sow the seeds in late summer or fall, but do it as soon as possible after collecting and drying. The seeds can be sown in the spring, but require four to eight weeks of stratification. If you want to plant the seeds indoors, plant them in sand with peat added. Lightly cover the seeds or press them into the surface of the soil. Cover the container with plastic or glass until the seedlings emerge. For outside planting, lightly rake the seeds into soil and then cover the area with boughs or brush to provide some shade and protection during the first few months of summer. The germination rate is poor, so sow thickly. Good luck! I don't blame you for wanting to perpetuate this beautiful tree, especially for the reason you listed.

Q: I have a dieffenbachia that I keep at work. It was doing well, but it looked awful after I came back from Christmas break. It had fallen over and looked like a giant had stood on it. All the stems that were upright had collapsed and fanned out. Have you ever heard of this? I was very worried, so I gave the plant a lot of water. I also found out that the heat was turned off during the break! Was it the cold that caused this problem? The next day the plant was standing upright again, but not looking as healthy. A lot of the bottom leaves have turned yellow and dropped off since then. Is this just a natural shedding of the lower leaves? The plant is bushy on top. (e-mail reference)

A: It sounds like your plant suffered chill damage and water deficiency during the break. I am happy to hear that the plant stood back up after the watering you gave it. From this point on, be patient. The plant should make a full recovery because of the increasing light coming into the room as winter winds down. Don't make the mistake now of overwatering the plant. Allow it to dry down before watering again.

Q: We have a weeping willow tree that is 25 feet from a pond on a golf course. The tree has several large gaul growths on it. Some are larger in diameter than the tree. Is it worth trying to save the tree? The tree is a few years old. (e-mail reference)

A: A willow tree this young that has galls the size you describe is not going to make a good candidate for the future enhancement of the golf course. I recommend removal and replacement.

Q: There is a huge cottonwood growing near my house. I would like to take a cutting to grow another tree. When is the best time to take the cutting? What is the best way to get it to grow? Can I expect the cutting to produce a tree that has the same dimensions as the parent? (e-mail reference)

A: Poplar cuttings generally root easily if the wood is from the previous season's growth, but still dormant. If the cuttings are taken from a vigorous tree, the cuttings will be vigorous rooters. There are anatomical structures called preformed root initials in poplar, willow and hydrangea stems that were formed last growing season. These initials are stimulated to break dormancy and produce roots when they are severed from the parent plant and given the right environmental conditions, which usually is a sand/peat mixture. The initials also will need light. In doing this, you are producing a clone of the parent plant that will have exactly the same genetic makeup as the parent tree. Given the same or similar environmental conditions, the cuttings should develop into trees of similar size and vigor.

Q: We gave our plant more light and stopped watering it, but the leaves are continuing to turn brown and die. The new leaves have brown tips and the branches have started to become dry. What should we do? (e-mail reference)

A: Be patient. Check the cambium under the bark with your thumbnail to see if it is still green. If it is, the chances are good that the plant eventually will releaf. If the cambium is yellow or brown, the plant is dead. I suggest doing the cambium test on the main stem to get an accurate indication of the health status of the plant.

Q: I have an ivy hedera helix that I'm using for a science experiment. I was wondering how often it needs to be watered and how much water it should be given. Also, should I use mineral, tap or distilled water? If you could get back to me as soon as possible, I'd appreciate it. (e-mail reference)

A: Hedera ivy is a tough plant, so it doesn’t need a lot of water. Twice a week would be more than enough. As far as the quantity goes, add enough to have it come out of the bottom of the pot into the saucer. After 20 to 30 minutes, dump the excess water out of the saucer. Using distilled water eventually would leach any nutrients out of the soil and would cause nutrient deficiencies to begin showing up on the plant. Tap water may offer a good or bad bank of salts, especially if the tap water is softened chemically. The sodium would accumulate in the soil and cause stunted growth or sodium burning on the edges of the leaves. It all depends on what you are attempting to do with your experiment.

Q: I have a jade plant that I started from a clipping about five years ago. It has been growing beautifully and is very healthy. I’ve had it in my sunroom since I started it. About a week ago, I moved it to another part of my house. Now the main and smaller stems have drooped. I moved it back to the spot that I had it in previously and used a stick to prop it back up, but it still is slumped over. Any suggestions? (e-mail reference)

A: Be patient. Do a close visual examination of the stems at ground level to try to detect any potential rotting. If nothing is found, then knock the plant out of the container and examine the roots for rot. If that is the case, all you can do is try to root some stems or leaves from the plant before it is too far gone. This usually is something that takes time to develop. Moving the plant to another site may have been the trigger that was needed to manifest something that was going on for some time.

Q: We got an advertisement in the mail for a royal paulownia shade tree. The cost of the tree was advertised at $3.98. The tree is said to be hardy to minus 30 degrees and will grow in any type of soil. I’m wondering about the advertisement because I can’t find the tree listed in other seed catalogs. (e-mail reference)

A: Oh, how the snake oil flows! Paulownia tomentosa is right behind kudzu and ailanthus for its invasive and persistent qualities. Where they are adapted (zone 5 and south), they grow like the weeds they are. When the flowers fade and the seed pods are formed, there are some 85,000 seeds per ounce, with one tree being capable of producing 20 million seeds, with most being viable! It does have some value because the wood is prized by the Japanese. They use it for rice pots, bowls, spoons, furniture, coffins and air crates. If you live in zone 5 or higher and have land that cannot be used for anything else, this might be something to consider growing for the Japanese market!

Q: I heard canola oil will control aphids. Is this true? If so, is it safe to use on my hibiscus? (e-mail reference)

A: Most vegetable-based oils are good for aphid control on many plants. However, I can’t tell you if it is safe to use on hibiscus because I’ve never tried it. I suggest trying it on a limited basis, such as one branch, to see if it works without causing the plant to whither or die.

NDSU Agriculture Communication

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