May 16, 2002

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: My first question concerns purple cone flowers that seem to have deformed blooms the past two years. Is this aster yellows disease? Should I destroy them and replant? My second inquiry has to do with a local landscaping project I'm working on for my church. I did a soil test. Also I realized when digging for the soil sample the good black dirt on top of the area to be planted is only 8 to10 inches deep with clay below. Our plan was to lay down biodegradable mulch first then plant an assortment of easy care perennials, bushes, and ornamental trees that are drought tolerant with wood chips around all plantings. The "black dirt" soil sample shows organic matter 4.2%, pH 8, Olsen Phosphorus 31, Bray 1 Phosphorus 5, K 121. They recommended using a fertilizer ratio of 15-0-20 / 100 sq ft. Will it work, since we're doing a pretty large area, if as we plant we add black dirt and fertilizer to each area being dug? We planned on adding good soil to all holes dug for the bushes and trees for sure. When adding fertilizer by this method I'm unsure about amounts. (Kandiyohi, Minn.)

A: Unless you know where to get a fertilizer with that analysis, I would opt for what is known as a "garden fertilizer," one that typically has an analysis of 10-10-10, and working it into the soil at a rate of about 10 pounds per 1000 square feet (or 1 pound/100 sf). You shouldn't be so fussy. I know plenty of folks who would be delighted with 8-10 inches of good topsoil! I don't think you will have any problem growing whatever you want. The symptoms with the purple coneflower does sound like aster yellows. I would suggest digging them out.

Q: We recently purchased a beautiful Amur maple for our backyard. We have two dogs, and I want to make sure that the flowers, seeds and fruit produced by the tree are not toxic to animals. (E-mail reference)

A: They are not - don't worry and enjoy!

Q: I am planning a late November wedding and would like to grow pots of calla lilies to place throughout the reception hall. I am not sure of the best way to begin growing the callas indoors, or if the timing of my wedding is correct for the plant's cycle. Could you instruct me as to the best way to go about this task? Also, is it possible to guarantee that my callas will bloom in time for my wedding? If so, when should I plant my bulbs? (E-mail reference)

A: If you want a guarantee on bloom timing, find a florist and place an order. As homeowners, we lack the facilities to control the factors of growth well enough to precisely time the blooming cycle.

Q: We have a hedge of amur maples that is about 40 feet long. They have grown to about 10 feet and the new growth each year is almost impossible to trim as they are also wide at the top and it is difficult to reach the middle of the hedge with a ladder. We would like to trim the hedge to a height of 6 feet. Would this damage the hedge? If the hedge can be trimmed to this height, what would be the best time of the year to do this serious amount of pruning? (Dickinson, N.D.)

A: If it isn't snowing in Dickinson today, get out and do it ASAP. You want to get this done before the new growth comes out. You might consult with Craig Armstrong, the city forester, about how, specifically, to go about this. He's a good man and knows his stuff!

Q: My daughter recently received a Dieffenbachia. It was beautiful. Now the leaves are getting yellow and are curling. Any suggestions? (Steele, N.D.)

A: It sounds like it is getting "sunburned." If it is getting direct sun at all, move it. This is one of these "office" or "parlor" plants that do well in low light situations.

Q: I have two Christmas/Easter cacti . When they bloomed I took the blooms and cross pollinated then. Now I have seeds pods forming. My question is, do I wait for the pod to fall off or do I wait for it to dry on the plant or do I open it and sprinkle them onto potting soil? (E-mail reference)

A: Wait for the pods to dry on the plant, then excise the seed and plant.

Q: We were considering putting in an Amur maple (bush variety) and were told that they produce the seeds typical of some maples, which we do not want. Others have told us they have the Amur maple bush and have no seeds. Are there different varieties and which one would you recommend for good fall color and no seeds (if there is such an animal)? (E-mail reference)

A: The Amur maple produces seeds that are very ornamental in many cases, but never a nuisance. I've had one growing in my back yard for over 15 years, and while it does produce very colorful samaras in mid to late summer, they have never been a problem with sprouting in flower beds or the lawn. That being said, I have seen this species without seeds. You might look into the compact forms: 'Compactum', 'Durand Dwarf', 'Emerald Elf' and 'Red Rhapsody'. The latter is not a dwarf, but a full size for the species, with knock-out red fall color. I am not guaranteeing those I have named are seedless, but they are not touted for their showy seeds.

Q: I am still trying to find a source for purchasing a Copper Curls Pekin lilac. I called Bailey's and they are strictly wholesale. They said Bachman's carries their stock so I tried a local Bachman's. The lady there said she would need to know the botanical name to help her figure out what is what. I didn't know the Botanical name. Do you have information like that? (E-mail reference)

A: This is an NDSU introduction developed by our woody plant researcher, Dale Herman, and is known as Syringa pekinensis 'Sun Dak', aka Copper Curls Lilac. You may be a little ahead of the curve on the availability of this plant, as it has just been released to the trade and was expected to be available retail by 2003. If anybody would have it, Backman's would, or they could tell you when it would be available.

Q: Rhododendron trees are now available in our area. Do you recommend them for outside planting? (Fessenden, N.D.)

A: No, because I have not heard any results of their hardiness. Until I do, and get it confirmed professionally, I'll withhold my recommendations on them.

Q: I just bought a pot of six spider plants. One of them has what looks like a stem growing up next to it but it is not growing at all. Is this what the plantlets come off of? Will the other spider plants have these? How long will it take if they will? (E-mail reference)

A: Yes. Plantlet production is dependent on daylength. Give it more than 12 hours of bright indirect light with some direct sunlight thrown in, and you should see some new plantlets coming on shortly, generally in about six to eight weeks.

Q: I have two peace lilies. I would like to take them out of dirt and put them in a vase with water and marbles. If I do this will it cause damage to the plant and if not what is the best way to take care of the plant when it's in water? Also, I use mayonnaise on the leaves of the plant to give them a nice shine. Is this OK? My last question, when the tips of the leaf turn brown I pick it off. Is this to okay or am I harming the plant? (E-mail reference)

A: The plant should be all right. Just keep the water fresh, never allowing it to go stagnant. It is OK to use mayo, but don't overdo it. Distilled water does a good job without the oil buildup. And finally, no, you are not harming the plant by picking off the brown tips.

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