May 3, 2001

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I have two large hibiscus (one double and one single). Both are full of buds and blooms and have been all winter, but they are getting very large and I want to trim them back. I have been waiting for them to quit blooming but that doesn't seem to be happening. Do I cut them back anyway? They are in the south window and I water them when leaves start to droop. (E-mail reference, Sanborn, N.D.)

A: Yes, go ahead and prune them back to size. Congratulations on getting them to flower so continuously! You must have found the ideal location for them to have an ideal life.

Q: I mixed up my own soilless mix for starting seeds using three parts peat moss and one part vermiculite. Now I have what appears to be damping off disease. I have several flats growing under lights, and one or two plants keel over every day. Is there anything I can do besides dumping them all in the garbage? I thought soilless mix wasn't suppose to have damping off. (E-mail reference, Driscoll, N.D.)

A: The pathogen can be seedborne as well, and given the right conditions ( damp, warm, no-air movement environment) the damping-off fungus will become active. I suggest setting up a little fan to move the air across the seedlings and stretch the time between the waterings a little, trying not to splash when you do water. If the fungus appears to be migrating from one end of the flat of seedlings, cut out a couple of rows, media and all, and dispose of it.

Q: I was reading something on the World Wide Web the other day that suggested distilled water is bad for house plants (especially African violets) because it can rob the plants of essential salts. Then in some responses you wrote you seemed to be advocating distilled water. Can you give me some direction on this issue? (E-mail reference)

A: Distilled water is ionless, and continued use of it in a soilless media would indeed leach it free of just about all nutrients. However, in our part of the country water is quite often loaded with salts, resulting eventually in salt build-up to the point of toxicity, or at least some physical damage. When I was working in Saudi Arabia back in the early '80s, I saw dramatically how nearly distilled water (10 ppm soluble salts) resulted in a very positive growth response to our nursery stock after being stifled by too many salts. So my advice is, if chronic salt problems exist with your water supply, water about once per month with distilled water to leach some of those salts out of the soil mix; or, if you want to control what salts the plant gets, then use distilled water as the base, adding just small amounts of the needed nutrients each time. Keep in mind too, that all soils, with the exception of sand, have a pretty decent cation exchange capacity, which hold the nutrients against leaching water. The most leachable nutrient is nitrogen, which is easily replaced if needed, but most houseplants do not need a great deal of this element anyway to grow normally.

Q: I have a schefflera that my mother gave me. Now I have a rabbit that loves to eat it, and I want to make sure that it won't hurt it. Also I have birds (parkeets, cockatiels, conyer). Is it harmful to them? (E-mail reference, Kansas)

A: You have nothing to worry about. Schefflera has no poisonous record, so it shouldn't hurt your bunny or birds. That is, of course, assuming that no one has used an insecticide, either surface or systemic, on the plant recently.

Q: I have just returned from more southerly climes and find many of my pine bushes and trees with brown edges, which I think come from sun burn. I think Miracid is the answer, but the question is, how warm should it be before I apply, and how many applications? (E-mail reference, Bismarck, N.D.)

A: Don't do a thing at this time. The damage was done either this past winter or earlier last year. If the plants are going to recover, they will do so on their own. Adding Miracid or any other fertilizer at this time will do no good. In fact, it may only compound the problem.

The buds will soon be breaking on the pines, and the new candle growth will elongate. If the older needles are not dead, they may re-green; if they are dead, they will drop off some time during this upcoming season. Protection is needed in the fall, prior to winter's arrival, by spraying the needled evergreens with an anti-desiccant like Wilt-Pruf and spraying again during a thaw in mid-February or early March.

Q: I have a question for you about fuchsias. I have several houseplant books (I'm a beginner) that seem to indicate fuchsias will make excellent houseplants, especially in a shady area of the room. I went to a greenhouse to buy some fuchsias and the owner would not sell them to me as houseplants because he felt they could only be grown outside. Can you help me with this? I do not want to kill my plants but I would love to have a fuchsia for inside. (E-mail reference, Virginia)

A: Fuchsias are both houseplants and hanging basket annuals that are used extensively outdoors during the summer in shady locations. You need to contact a local florist to get a fuchsia that has been cultured as a houseplant. It shouldn't be difficult. The greenhouse was going to sell them as bedding plants or hanging basket annuals. I think as a "houseplant" source, there would be more cultivars for you to select from. Call around to your local florists to see what you can find out.

Q: I have big, overgrown cherries with insects inside. What's the best guess on what the problem is, what product can I use and at what time? (E-mail reference, Linton, N.D.)

A: These are the chokecherry midge larvae. The only answer is to remove the infested fruits shortly after they appear to reduce the numbers next season. No chemical treatments have proven effective for this pest.

Q: We just purchased a new home in Bismarck and we need to plant grass. The contractor planted oats on the lot last year as a temporary cover. The lot is on the edge of town next to a field, so you can see a lot of weeds and weed seeds mixed in with the oats. Lawn contractors which are recommending we spray with Roundup first, but two contractors have totally different bids and totally different ways of preparing and planting grass. We plan to install a sprinkler irrigation system. Contractor A plans to spray Roundup, wait seven days, and then till the soil, level, have the sprinkler system installed and hydroseed. Contractor B plans to spray Roundup, wait seven days, run a rake/harrow over the ground to remove dead weeds and level the yard, install the sprinkler system and drill seed. Questions: Should the soil be tilled 4 to 6 inches deep, or is the Contractor B method of disturbing the top 1 to 2 inches OK? Will the grass grow well with the Contractor B method? Are there any disadvantages to not tilling 4 to 6 inches deep?

What seed blend do you recommend? Contractor B recommends the following 30 percent Park bluegrass, 30 percent Baron bluegrass, 20 percent creeping red fescue and 10 percent rye.

I understand that Washington, Rugby, and Meredith blends of bluegrass are better than Parks and Baron but cost more. Would you pay more for these varieties? How will I know when to spray Roundup? Do I just wait for weeds to grow? Is seven days the proper length of time to wait before raking or tilling? Any other advice? (E-mail reference, Bismarck, N.D.)

A: You would actually end up with a pretty good stand of grass from either contractor, but given my druthers, here is what I would suggest: Have the irrigation system installed after the current grass/weed population has been killed off by Roundup. The seven days is arbitrary. It could be seven, 10, or more, depending on the temperature. The important thing is to make sure everything has turned brown before taking any further action. Get the system installed so you can sprout your grass with it. The mixture suggested by Contractor B would be a good one if there was not going to be an irrigation system. I would suggest some of the elite Kentucky bluegrass cultivars, like Merit, Glade, NuBlue, and Kelly. These elite cultivars have done well in our variety trials and would perform to your satisfaction under an irrigation system. You will want about 10 to15 percent of the seed applied to be a turf quality perennial ryegrass. It is worth the extra money to get the right cultivars planted the first time; it would be more than twice as expensive to do it over again. If the housing contractor left you with a decent grade, there is no reason to till everything up again. It will only pull up more weed seeds. Drag-raking over the surface will be sufficient, and drilling the seed in would work as well, as long as it was done in two directions, perpendicular to each other. He will probably be using a cultipacker to drill the seed in; most lawn contractors do. You will have a minor problem around your sprinkler heads with some of the seed washing out. You can solve this by purchasing some bluegrass sod locally, and centering it around each sprinkler head. It is not anyone's fault, just the law of water physics that is annoying to those of use who do this work! If you are going to be the one spraying the Roundup, wait until things turn green and begin growing for maximum effectiveness.

Q: I have an ornamental purple leaf plum tree (P.cerasifera 'atropurpurea' ) that was planted in 1998. For some reason, only the center main trunk still puts out branches with purple leaves. Lower on the trunk are lots of branches with green leaves, and all suckers have green leaves too. Is there anything I can do to encourage more purple leaves? (E-mail reference)

A: That simply means that the graft for the purple leaf character is not dominant enough to suppress bud break, or growth, below it. I encourage you to prune the lower green growth out when it is apparent, and hope the scion wood can become dominant enough to keep the sucker and unwanted growth in check.

Q: What do fruit trees and fruit-bearing bushes need for fertilizer? What about spraying? I don't like to do spraying any more than I have to and am trying to attract butterflies and birds to my yard. I have a terrible aphid problem on a current bush. What kind of spray could I use? Are there some good, simple landscape software programs or web sites that I could get practical ideas from? I love to look at garden catalogs and books but they always seem to be for another zone and assume I have the perfect soil. I have to work around gumbo-on-shale soil and within a short growing season. (E-mail reference, Rapid City, S.D.)

A: Generally fruit-bearing trees and shrubs don’t need fertilization on a regular basis unless you are in it for commercial purposes. I usually advise people to respond to any diagnosed deficiency that shows up. Most yard grown trees and shrubs get adequate nutrients as a coincidence from turfgrass care. To control aphids on your currant bush, I suggest using insecticidal soap as soon as you see them. This is safe material for you to handle, allowing you to eat the fruit without a worry. Spraying, again, should be in response to a diagnosed problem, not just as a prophylactic action. Local garden supply stores carry many lines of insecticides and fungicides that you can use. Simply spray in the early morning or late evening (before sundown) when the insects and birds are less active. Try my website. Just about everything is published there: www.ag.ndsu.nodak.edu/horticulture.htm 

Q: I live in northern Montana so I think the problem would also apply to your area.

I overwintered some dinner plate dahlias in my basement in a container of peat moss. About a month ago they were showing a lot of dryness so some water was added to the container. Several of the roots now have long sprouts. Should these be removed? Should the roots be planted in containers and then kept indoors until such time as they can be planted outdoors? (Choteau, Mont.)

A: Don't remove the sprouts! The corms are doing exactly what you want them to do. All you need to do at this point is to pot them up and place them in as sunny a location as possible and plant outdoors when danger of frost is past.

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: Gary Moran, (701) 231-7865, gmoran@ndsuext.nodak.edu