Companion plants help beat bad bugs

June 09, 2009|By ANNETTE IPSAN

Would you like to discover an easy, chemical-free way to beat bad bugs and boost your plants' health? Try companion planting.

An old method that's suddenly new again, companion planting uses plant combinations that repel or confuse bad bugs, attract good bugs or enrich growing conditions. It's especially helpful in vegetable gardens.

Discourage bad bugs

Would you like to discourage those big, fat juicy tomato hornworms that plague your tomatoes?

Try planting basil around them. Because most insects find the plants they want to munch by scent, heavily scented plants like basil and garlic confuse them, making it tough to find their target. And let's face it, if you're going to have fresh tomatoes, isn't it nice to have some fresh basil and garlic around so you can whip up a tasty pasta dish?

A few other plants that discourage bad bugs are catnip, tansy, radishes and artemesia.

Marigolds are the real miracle workers, though. Aromatic marigolds not only confuse many bad bugs with their scent, but repel soil-borne troublemakers called nematodes, too.


Attract good bugs

Another way to use companion plants is as a lure for good bugs, beneficial insects that help control bad bugs by eating them or laying eggs on them.

Most beneficial insects are small and are attracted to smaller flowers from which pollen can more easily be collected and from which nectar can be sipped. By planting small-flowered plants such as chives, parsley and sage, you can draw in these good bugs to wrangle the bad guys. Cilantro, rosemary, lemon balm, thyme, sage, dill, fennel and hyssop also attract beneficial insects.

Enrich growing conditions

Companion plants can also improve plant growth. Plant radish seeds with your carrot seeds so the quick-sprouting radishes can mark your planting row and break up the soil for the slow-to-sprout carrots. Let pea vines project young tomato transplants from northerly winds. And plant fall cover crops such as red clover or winter rye between your cool weather crops to enrich the soil when they are tilled into the soil in the spring.

Making it work

The Native-American "three sisters" planting system of corn, beans and squash is a perfect example of companion planting. The beans grow up the corn stalks and enrich the soil by fixing nitrogen. The squash growing at their base discourage weeds, hold moisture and make it harder for animals to snack on the corn and beans.

Resources aplenty

There are many books on the subject of companion planting that can give you specific plant combinations that work. Two favorites are "Great Garden Companions" by Sally Cunningham and "Carrots Love Tomatoes" by Louise Riotte. There is also a fine article by Master Gardener Darlene Widerstky, "Herbal Companion Planting in the Vegetable Garden," at

I also have a free companion planting guide for vegetables prepared by local Master Gardener Karen Greeley for our recent Veggie 101 class. I'd be happy to mail you a copy if you send me a self-addressed stamped envelope. Just mail your request to Companion Plants, MD Cooperative Extension, 7303 Sharpsburg Pike, Boonsboro, MD 21713.

You can see companion planting at work by visiting our new vegetable demonstration garden at the Ag Center. Our Master Gardener volunteers have tucked in marigolds, basil and chives among the vegetables. You can also make a virtual visit to the teaching garden at our Extension Web site, under "horticulture," where you'll also find an archive of some of my past gardening columns.

I hope you'll consider trying companion gardening in your own backyard. It's a wonderful way to thwart pesky pests and improve the health of your garden.

Annette Ipsan is the Extension educator for horticulture and the Master Gardener program in Washington County for the University of Maryland Cooperative Extension. She can be reached weekdays by telephone at 301-791-1604 or by e-mail at

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