August 25, 2005

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I have mushrooms growing in the soil of my hibiscus plant. I move it outdoors in the summer. The mushrooms recently have grown large and are pale yellow. Do I need to throw out the plant? (e-mail reference)

A: The mushroom simply is tangible proof that the organic matter is being broken down and that the media is moist or wet. If it bothers you, pick off the mushrooms and throw them away. The mushrooms are not hurting the plant.

Q: My strawberry patch is being taken over by dandelions. Is there anything I can use to get rid of the dandelions, but not hurt my strawberries? (e-mail reference)

A: Sorry! Good old-fashioned digging of the entire root is the only answer now, unless you want to kill everything and start fresh.

Q: I replanted a 10-year-old cactus. Now, its body is 60 percent black and fading fast. Should I repot it with just the “good” part? I think I overwatered and used the wrong soil. Is there a Miracle-Gro for cactus? (e-mail reference)

A: Try cutting off the nondecayed top and allow it to “cure” for a couple of days before planting it to see if you can get roots to form from the cutting. There is no Miracle-Gro for cactus.

Q: This year I decided to buy wave petunia plants and create my own hanging baskets. The plants were full of flowers when I planted them, but over the course of two weeks all the flowers dried up. I now have green plants with no flowers. I have been using Miracle-Gro Bloom Booster once a week, but it seems to have had the opposite effect. The plants were sometimes put in direct sunlight for part of the day, but mostly hung in indirect sunlight. Any suggestions? (e-mail reference)

A: It sounds like you planted petunias outside that had not been hardened off. Treat them normally, but don’t overwater or overfertilize. They should begin to recover in a couple of weeks.

Q: A friend of mine gave me four hosta plants. How far apart should I plant them? What can I do to prevent slugs? (e-mail reference)

A: Plant them 12 to 18 inches apart, depending on what effect you want and how soon you wish it. As to preventing slugs, you can’t. Slugs and hosta go together like potatoes and Colorado potato beetles. All you can hope to do is keep them under control by not overwatering and doing a good cleanup in the fall. If they should get out of hand, there are the usual remedies available at local garden centers.

Q: How do I test the soil for pH? Is there a test kit I can buy or do I have to take a sample to a county Extension Service office? (e-mail reference)

A: The test kits that can be purchased are not reliably accurate and have limitations in range. You are better off contacting the local Extension Service office to get a bag or two from it to use to collect the soil. Then order a nice snapshot of N,P,K, pH, SS (soluble salts) and the organic matter present.

Q: My amaryllis has produced a seedpod. What suggestions do you have to improve germination? (e-mail reference)

A: Sow the seeds, but barely cover them and keep them moist, but not soggy. Keep the seeds at room temperature. The resulting plants should flower for you in three to four years.

Q: I have two large rhubarb plants in my vegetable garden. The leaves are huge and the stalks get long and thick, but they remain mostly green. Is this a different variety than the common red kind or are my plants not getting enough sun? Last spring I kept waiting for them to turn red, but they got woody instead. (e-mail reference)

A: Sounds like you have wild or common rhubarb instead of the valentine red.

Q: I have glowing ember hydrangea bushes. They are growing out of the ground quite well, but all of the old stems are dead and not growing. Should I prune them or will I get growth on the old wood? (e-mail reference)

A: Prune them. Your hydrangea will flower on the current season’s growth. Last year’s growth is dead and is of no use to the plant.

Q: I have a flowering crabapple tree (I think) in my front yard. From the roots, there are little shoots sprouting up all over the yard. What do I do to stop that? (e-mail reference)

A: Prune them back to the root and get some Sucker Stopper RTU from a local garden center. Spray it on the pruned spots. It will not produce new suckers there again.

Q: How long should wood chips be aged before using as mulch? (e-mail reference)

A: I would like to see it go for a season or six months, if possible.

Q: Is there a difference between male and female spider plants? I have some baby spider plants that I am rooting, but I was told that I need a male and a female plant to grow them. I’m not sure what a male spider plant looks like. Also, can I plant different types of spider plants together? (e-mail reference)

A: There are no female or male spider plants. You should be able to grow them without that to worry about.

Q: I have a client who is planning to plant a few horse chestnut trees this spring. He has heard that the leaves and the chestnuts are poisonous. Do you know if that’s true? (e-mail reference)

A: Horse chestnuts are poisonous and are not dependably hardy to North Dakota. Your client probably is talking about the Ohio Buckeye chestnut. Ohio Buckeye is toxic to horses, but can be grown in most parts of North Dakota.

Q: I have a rosebush I had to relocate and now some of the leaves have a yellow line on them. Could you please tell me what to do? The bush has blooms on it and everything else looks OK. (e-mail reference)

A: Those lines could be the result of damage to the root system, which could be limiting the uptake of nutrients. Apply a fertilizer, such as Miracle-Gro, once a month during the growing season to help get the plant established.

Q: I have a very clay soil. Cabbage, broccoli and cauliflower grow well in my garden, but the cucumbers turn yellow and do not produce very well, if at all. I’ve brought in sand in the past. Using sand, the onions, potatoes and peppers do well, but the sand disappears after a year. The garden is surrounded by grass and is on flat ground, but there is a hill about 30 feet away. We brought in more soil from Streeter because it is sandy. Can I “bake” the soil to destroy the weeds or would it decrease the nutrients? (The soil was full of quack grass.) How can I keep the sand from leaving the garden? Why don’t cucumbers grow in my garden? Is there a missing nutrient? (Jamestown, N.D.)

A: Forget using sand. Instead, use large amounts of sphagnum peat moss to work into the upper 6 to 9 inches of the soil. “Solarizing” the soil will help get rid of some of the weeds, but not all because some weeds are heat resistant until the temperature gets above 170 degrees. The reason your cucumbers turn yellow is probably because of the high pH and/or high clay content. The addition of peat moss should go a long way toward making nutrients available to the plants.

Q: I planted daffodil bulbs last year. The shoots came up, but no blooms. Will they come up next year or should I replant? (e-mail reference)

A: If the leaves came up, that is at least a good sign. I would allow them to stay through next spring, but if flowers do not grow, dig them out and replace.

Q: I have a paper birch with three main trunks. Last year everything was fine. This year it looks as if two of the trunks area dead. One trunk does have a new shoot on it. Most of the branches break off. What is going on? The third trunk seems fine. (e-mail reference)

A: Sounds like bronze birch borers have moved in and destroyed the tree. Look for d-shaped exit holes about the size of pencil lead in the branches and trunk. It is just a matter of time before they move to the remaining trunk.

Q: Our lilac is about 18 years old. This spring it began to flower in May. After a heavy rainfall, it toppled over and was uprooted. Is there anything we can do to save the tree? It is lying on its side. (e-mail reference)

A: You can try resetting the lilac as best you can and see if it will survive. There is bound to be some die-out from this kind of treatment. With a lilac that old, there are bound to be some roots that will send up suckers for you and begin the process over again.

Q: I need to eradicate some snow on the mountain. Digging it out is a real project because of its extensive root system. Is there something I can apply to the leaves that will kill the whole darn thing? I need to be careful what I use because the area also has rhubarb, coneflower and obedient plants. (Blaine, Minn.)

A: Good luck! The only stuff on the market is Roundup. Because of the other plants growing in the area, you will have to carefully paint the herbicide on the leaves and hope for sufficient translocation to kill the entire root system.

Q: I have what I believe is a white/cream hydrangea bush in front of my apartment that I love. Can I cut a branch and get it to root? I’m moving and would like to try to root my own tree if possible. (e-mail reference)

A: A nonflowering branch will root, a flowering one will not.

Q: My Norway maple is about 80 years old. It started to get long splits in it and dripped sap. Wherever the sap gets on the bark, it eventually dies. Half of the main trunk is dead and many splits have occurred. There is a sugar maple very close to the problem tree and just as old. It had a problem where the top of it died. I fertilized it with 10-10-10 and it grew faster than the disease could damage it. It is now doing well. Could you tell me what this disease is and how to save the tree? (e-mail reference)

A: The disease is known as bacterial wetwood or slime flux. The infection originates from the sapwood because of previous injury to the tree. Generally, there is little that can be done except to drill a hole in the tree and insert a copper tube to help drain the sap from the trunk onto the soil. If you had luck fertilizing the sugar maple, give the Norway maple a similar treatment to see if that helps. You have nothing to lose.

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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

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