June 12, 2003

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I have been using distilled water with a small amount of Miracle-Gro for many years. My plants seem to be okay but I wonder if reverse osmosis might be better. Am I giving my plants too much plant food? (E-mail reference)

A: Reverse osmosis (RO) water is all right for watering plants too. All the RO process does is remove most of the salts, generally down to about 10 parts per million, which is very close to distilled water. I think you may be overdoing it with the Miracle-Gro since you use it each time you water. Using it once every two weeks is adequate.

Q: How do you kill mushrooms coming up in a newly seeded lawn? (Linton, N.D.)

A: You don't. They will come back again when the moisture conditions are right. To eliminate mushrooms, get rid of the decaying organic matter they are feeding on. Some people pour a 10 percent solution of bleach into the soil at the base of the mushrooms but that is only a temporary solution and potentially harmful.

Q: I’ve got a veggie question for you. I know a man who has greenhouse tomatoes that are 8-10 inches tall. I don’t know the variety. The top leaves are curling but not discolored. He uses rain water and says the bottom leaves look vibrant and healthy. Any ideas? ( Bowman, N.D.)

A: It’s nothing to worry about -- just something that happens with many cultivars of tomatoes as they grow. It is believed that this is a reaction to high temperatures, sort of a built-in plant water conservation technique used by the most tender and vulnerable leaves.

Q: I have a beautiful lilac shrub growing in my backyard. Since I don't spend much time in my backyard, I would like to transplant half of the shrub to my front yard. Is it possible to pull part of it at the root-ball and transplant that part or would it kill the whole shrub? (E-mail reference)

A: You can but not now unless you live inside the arctic circle. It would be better to wait until next spring, perhaps around the first of April while they are still dormant, to do the dividing.

Q: A week ago I heard on our local news that we should not add gypsum to our gardens as it is too high in sodium. Is this true? Also, I need to move a lot of my peonies. When is the best time and do I cut them back before I move them? (Fargo, N.D.)

A: Gypsum has two elements, unless it has changed since I went to college, calcium and sulfur but no sodium. It is formulated to replace the sodium ion that has built up in soil with calcium to improve the tilth and drainage. It is only effective if adequate quality water can be added to the soil to leach the sodium ion out and replace it with the calcium. Peonies can be moved in early spring before they begin active growth.

Q: I have a red leaf maple that we planted three years ago in our small yard that is in the middle of a forest. The trunk is 5 inches in diameter and about 15 feet tall. The tree seems to be growing taller than wide with one branch rising above the rest. Should I trim the top branch to promote wider growth? Is this due to the height of the surrounding trees? (E-mail reference)

A: Surrounding trees will impact your maple. A maple’s natural form is a rounded so go ahead and prune to meet your needs.

Q: What are the options for a large poplar tree that is sending out suckers up against the foundation of a house? Can they be sprayed with a contact like Roundup without causing too much damage to the tree itself? (Hettinger, N.D.)

A: Apply Sucker-Stopper, a commercially available product in garden centers. Also, a product known as Biobarrier may need to be installed to keep the root system in check. Roundup is a bad option because it is absorbed into the tree's vascular system which could cause problems beyond killing the suckers.

Q: I have four arborvitae planted around the front of my house. They have turned brown from the bottom to almost the middle. They looked fine before winter set in. We have a little mutt and I believe he has made a habit of urinating on them. Is it possible my dog has affected my plants or are they shedding? (E-mail reference)

A: There is no return from foliage browned by dog urine. Either accept the condition or train your pooch to go somewhere else.

Q: I had a lady call regarding her tomatoes. The plants she has seem to be growing quite tall but not bushing out. She is wondering if it’s okay to pinch them back to promote lower growth? Also, what do you think of the blossom spray products? I have a flower bed in town that a lady has had trouble with the last two years. The geraniums and petunias have severe yellowing. Could iron deficiency be a possibility? She also would like to know a source for buying a powdered iron supplement. (Hettinger, N.D.)

A: Yes, she can go ahead and pinch back the tomatoes without any effect. She may be using too much nitrogen fertilizer. Blossom spray products are fine but usually aren’t necessary. The yellowing of the geraniums and petunias could be an excessive salt accumulation and/or too high a pH. Iron sulfate may solve the problem. Chelated iron would be better if it can be found. Most garden stores have some kind of iron fertilizer product.

Q: My husband sprayed our lawn for dandelions with 2,4-D. The dandelions are still standing like tin soldiers. Did we use the wrong spray? What should have we used? Does 2,4-D work well on other weeds? (Grand Forks, N.D.)

A: Defiant dandelions! The formulation may not have been strong enough or there was a rain right after the application. Usually, within 24 hours the dandelion stems will begin curling and gradually die. It works on many broadleaf weeds but you may need something stronger such as Trimec.

Q: I have several cats that are using my flower gardens for a litter box. I noticed that you have recommended using citrus peels. How often do you have to put out new peels and do you have to discard them when they get old or will they decay? Will the citrus peels attract any bugs that I might not want? What about sprinkling pepper on my mulch? I just planted some mint and wonder if that will keep the cats from coming around. (E-mail reference)

A: Citrus peels will breakdown and decay. You can also try garlic spray, onion spray, "trapping" them with catnip or spraying hot pepper spray over the mulched area. If you have a blender, take the citrus peels and give them a quick, coarse chop before spreading them out. More surface area equals more fragrance that cats don't like. Replacing the peels on a weekly basis should do the trick. Once they get the message they will find somewhere else to do their business.

Q: I have a beautiful white flowering crab that is probably 40 years old. It is in perfect condition and everyone who comes to my house gasps in awe when they see it blooming. However, I can't grow grass under it because it drops about 6 inches of apple blossoms just as the grass starts to grow. If I rake the blossoms up, I inadvertently rake up a lot of newly sprouted grass. If I don't rake, they smother the grass. Either way, I'm left with lots of bare patches. This has been going on since I moved to the house in 1986. What else can I plant under the flowering crab? Should I wait until the tree is done losing its blossoms, clean up the area and plant annuals? That would mean a lot of annuals. I estimate at least 20 flats because it's a very large tree. (E-mail reference)

A: The grass under my crabapple suffers the same fate. It’s mostly from the falling fruit not the blossoms. You should be able to grow perennials and annuals under the tree and the herbaceous perennials should be able to stand the onslaught of falling flower petals.

Q: When is it safe to trim my lilac bush? It is growing too large and I would like to cut it down to four or five feet. (Moorhead, Minn.)

A: It would be better to cut the tallest branches as close to the ground as possible. Do it to a third of the branches each year which should keep everything in check at about the right height for you.

Q: I noticed a yellow mold growing on my plant. I thought at the time that my 2-year-old daughter had dropped food or something on it. I scooped it out but then started to notice the same problem on other plants. I repotted the plants as soon as I noticed the mold. I have let my plants go dry thinking whatever it is it will dry out and go away but that doesn’t seem to work. (E-mail reference)

A: All I can tell you is that with sterilized or pasteurized potting soil and containers, this doesn't happen. It is a gross saprophyte that is not directly harmful to the plant. If you want to keep the same plants, go through the whole process again using new containers and pasteurized potting soil. Also, dip or wash the plants in a mild dishwashing solution.

Q: Last year we planted two beautiful Amur maple trees. Now that the warranty has expired, they haven't flourished. My neighbor told me about a spray that he used in early spring and fall that worked for his trees in the same situation but couldn't remember the name. My trees are finally getting several leaves at the bottom but the rest remains bare. Any suggestions? They cost me a fortune! (E-mail reference)

A: I would go back to the nursery you purchased them from. Something has killed your trees and they should at least meet you halfway with replacements or advise you on what caused their rapid decline. I suspect they may have been planted too deep from what you describe. No spray in the world is going to bring dead tissue back to life.

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