Problems Growing Zinnias by Seed


QUESTION: For the past two years I have unsuccessfully grown zinnias from seeds of two different seed producers. The plants have grown well, but the flowers have come out smaller than described and with only a single row of petals instead of the full glorious ones pictured on the seed packets. I feel disappointed, as I feed and care for them well and have grown beautiful zinnias in the past. Although zinnia season has passed, do you have any suggestions which could help for next year?

ANSWER: I contacted three zinnia seed producers, and here is the verdict--basically, specialty zinnia seeds are a hybrid mixture, and sometimes there is a wide variation in the percentage of “true” types in the mix. Mixes vary, as well. For instance, “Dahlia Flowered” zinnias come in degrees of fullness, but often only the extremely full flowers are pictured on the packet. I understand that the “Sunshine” mix of “Dahlia Flowered” zinnias is pretty dependable. Some suppliers, also, are apparently more diligent than others at ensuring optimum percentages of “trues.” Several big name suppliers are good about this. And here are two less-known outfits that I trust: Shepherd’s Garden Seeds, 6116 Highway 9, Felton, Calif. 95018; and Stokes Seeds, Box Main P.O., Buffalo, N.Y. 14240. You might want to send for their catalogues. Better luck next year!

Rose Deformity By Any Other Name Is ‘Thrip’

Q: Not long ago you wrote about deformed roses; sometimes mine have the same symptoms you described (something eating out the “hearts” of the buds). However, gardeners tell me the culprit is thrips and not caterpillars. I would like to know what you recommend for thrips . . . and if thrips and caterpillars cause the same rose deformity.


A: To answer your last question first--no, caterpillars and thrips do not cause the same damage on roses. Caterpillars eat large, obvious chunks out of buds; it is easy to see, and it’s usually just a few buds here and there. Thrips destroy the tissues in developing buds, and opening blossoms are characterized by ugly, brownish, ratty-looking petals. Sometimes the damage is so severe that the buds do not open at all. Sometimes it just looks as if the edges of petals are scorched. Usually all the blooms on a plant are affected.

Thrips are nearly microscopic creatures that feast on succulent, tender petals before they unfurl, damaging the tissues so they partly die and expand improperly as buds open. The result is unsightly blossoms. To see if thrips are present, shake newly opening flowers over a piece of white paper: If thrips are there, some will fall out, looking for a moment like specks of dust, and then they will quickly start moving away.

Unfortunately, these little monsters are hard to control. Since thrips are most active and usually do the worst of their damage in spring, you could just ignore them and sacrifice the first flush of blooms (probably as you have already been forced to do). Or you could actively try to reduce their numbers in order to lessen the amount of damage they do.

Keeping weeds out of the garden significantly lowers the population of thrips. You may notice that the thrips seem to prefer certain rose varieties, in particular (usually the light-colored or soft petaled types); eliminate these from your garden and replace them with other selections. And, as a last resort, if these measures to not provide enough control, you might try spraying young buds with Orthene (according to label instructions) in early spring. The spray alone will not solve the problem, however. But all these efforts combined will normally make an appreciable difference.


Video on Pruning Roses

Readers: I’ve had so many requests for information on rose care over the years that I decided to make a new 30-minute video called “The Care and Pruning of Your Roses,” which demonstrates simple, yet successful techniques for the easy growing of beautiful in your home garden.

To order for yourself, or as a gift, please send a check for $18.99 per video (which covers the prices of the video, plus shipping, handling and sales tax) to Jack Christensen-Video, P.O. Box 1231-B, Ontario, Calif. 91762.

Please specify name and address of any gift recipients. Allow two to three weeks for delivery.