Archive for Wednesday, March 14, 2001

Double-agent plants lure bees, deter pests and add to garden’s bounty

March 14, 2001


In our continuing saga on companion planting, we now turn to the deployment of flowers and blooming herbs to attract the beneficial insects that (we hope) will prey upon pests and improve productivity in the vegetable garden, and to the strategic use of aromatics to ward off pests.

First, the bloom issue. Every vegetable gardener knows that a good deal of pollination is necessary to set fruit on blooming vegetables. Corn and cucumbers are among the veggies that require pollen to travel in order to produce, while the blooms of others, such as tomatoes and beans, have both male and female parts and can self-pollinate.

The breeze facilitates a lot of pollination. But I have known some impatient gardeners who have even used very soft paint and cosmetics brushes to make it happen, by first gently rubbing the stamens on one bloom and then dabbing at the pistil of another. This might be described as simulated plant sex.

It's a whole lot easier if you just let the bees help out.

Pollination will occur more quickly and reliably if you have a lot of bees in your garden. If you plant flowers near your vegetable plot, you can ensure that bees and other insects will be around when it comes time to pollinate.

Among other insects you like to have in your garden are parasitic wasps, syrphus flies and ladybugs, which eat aphids and other bad bugs.

Among the flowers that do a good jobs of giving beneficial insects what they need are yarrow, flowering herbs, daisies, cosmos, coneflowers and zinnias.

Flowers and herbs that give off strong aromas also may help keep worms and chewing insects away from your harvest, and can be planted liberally throughout the garden.

The most commonly used flower is the French marigold, such as the Safari Primrose, Sophia and Bonanza varieties. Not only do the flowers give off a strong scent, but the roots do as well. This may help drive away nematodes, which attack root crops. Marigolds are also relatively inexpensive and can be direct-seeded in the spring.

Basil set between tomato plants is said to ward off tomato hornworms. I've found hornworms a few times when I've also planted basil nearby, but the worms have been few and infrequent. Be prepared to make a lot of pesto, however, as you'll have plenty of basil to work with by midsummer.

Catnip may repel cabbage worms, aphids and flea beetles, the latter being the bane of eggplant growers in this climate. The downside of having catnip in your garden should be obvious. But if you garden in a catless neighborhood and choose to plant catnip, be sure to confine it in a container. Like other mints, catnip can become invasive.

Horseradish is a deterrent for potato beetles, but this plant also can wander and become difficult to control. Because horseradish sends its roots out more or less horizontally, I usually plant it in a large, submerged plastic pot. However, the roots are the most aromatic part of the plant and this strategy would be counterproductive.

The courageous gardener might plan to dig up the horseradish when the potatoes are harvested and allow an afternoon to churn up all the soil within a 6-foot radius of the original plants, in order to catch all the wayward horseradish roots.

Even if you don't plan to use flowers and herbs for insect control and to encourage pollination, a garden is a more pleasant place to be when you interrupt rows and rows of green with occasional splashes of color. Many of the annual flowers and herbs reseed themselves, and you'll see marigolds and cosmos reappear year after year.

When she's not writing about foods and gardening, Gwyn Mellinger is teaching journalism at Baker University. Her phone number is (785) 594-4554.

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