Companion Planting and Decoy Crops

By Susan Brackney

About the Author Susan Brackney writes about gardening, beekeeping, environmental affairs, the natural world and more from her home in Indiana. www.susanbrackney.com

Whether it's flea beetles making lace out of the eggplants or tomato hornworms stripping our favorite slicing tomatoes, we've all battled bugs.

With the right combinations of companion plants and decoy plants, we can battle garden bugs and save our favorite vegetables. Learn how to make companion planting a part of your garden.

Fortunately, besides handpicking, relying on organic, insecticidal soaps or employing lightweight floating row covers, organic gardeners have another weapon in their integrated pest management arsenal: companion planting.

By planting particular plants near one another, we can keep some insects at bay.

How Does Companion Planting Work?
Some companion plant combinations drive insect pests away.

Others attract beneficial insects that, in turn, help keep the numbers of harmful insects in check; still other combinations work to “trap” or isolate certain kinds of insects.

In this article ... How Does Companion Planting Work? Some Common Companion Plants Coping with Challenging Pests: A Few Tricks Trap Crops

Best of all, some companion-plant combinations can do all three!

Some Common Companion Plants
Marigolds and “pot marigolds”—also known as calendula—are some of the most well-known companion plants.

The scent of marigolds deters cabbage maggots, Mexican bean beetles, aphids and many other pests, and calendula turns off tomato hornworms and asparagus beetles.

Plant both throughout the garden—along crop rows and between plants—for a little extra color and added insect protection.

For trouble in the cabbage patch, try thyme, which is thought to ward off cabbage worms; and peppermint plants help keep cabbage butterflies away. Amongst your potatoes, plant catnip since it repels the pesky Colorado potato beetle. Because it also drives off flea beetles and squash bugs, catnip's useful near eggplant and cucumbers, too. Nasturtiums, likewise, can deter squash bugs, assorted beetles and some types of aphids.

Coping with Challenging Pests: A Few Tricks
Interestingly, some of the very plants that are repellent to insect pests—like peppermint and thyme—are quite attractive to beneficial insects that feed on aphids, mealy bugs and other troublemakers.

For the best results, you should have a good mix of perennial herbs and flowers along garden borders and interspersed with your vegetable crops. True, companion planting won't guarantee pest-free produce, but it certainly can help to make a dent in the numbers of problem insects.

Aphids
Sometimes found feeding on young cabbage heads, on the undersides of lettuce or spinach leaves, or even on sweet corn tassels, aphids are among the most common insect pests.

Thankfully, the larvae of green lacewings and ladybugs—as well as adult ladybugs—will eat large numbers of these soft-bodied freeloaders. Plants with clusters of tiny flower heads, like yarrow, coriander, Queen Anne's lace, fennel and dill, will attract both ladybugs and green lacewings.

Caterpillar
Many types of caterpillar wreak havoc on cabbage as well as broccoli, cauliflower, Brussels sprouts and assorted greens. The good news is that you can enlist predatory wasps to do them in. To attract the tiny, stingless helpers, try many of the same plants that appeal to lacewings and ladybugs along with lemon balm, parsley, chamomile, peppermint and catnip.

Leafhoppers
While eggplant, tomatoes, potatoes and beans often fall victim to leafhoppers, leafhoppers, in turn, can fall prey to the larvae of hover flies, which are attracted to many of the same plants as predatory wasps. Hover flies also will gravitate to English lavender, buckwheat, statice and sweet alyssum.

Trap Crops
You can protect your produce in one other particularly tricky way. By growing “trap” crops—plants well-known to attract specific insect pests—alongside any plants you wish to protect, you can divert attention away from your veggies and isolate the damage that problem insects can do.

Scented Geraniums and Four O'clocks
For instance, while Japanese beetles can be especially troublesome, you can draw them away from your green beans or those prized roses by planting scented geraniums and four o'clocks nearby. Although the adult beetles love to eat both, the flowers of scented geraniums and the leaves of four o'clocks happen to be toxic to them. And, although it won't kill them, borage is said to be another good Japanese beetle lure. Should you plant it as a trap crop, be prepared to handpick the insects daily to knock down their numbers.

Nasturtiums
Another popular trap crop, nasturtiums will attract large numbers of black aphids; to control their populations, you can handpick regularly or periodically treat with an organic, insecticidal soap. And for very heavily infested plants? Simply rip them out and discard well away from the garden.

Extra Vegetables
Planting an extra row or two of whatever vegetable you wish to grow can also work to trap and isolate insect pests since most insect pests stay on or near the host plants from which they originally hatched. Mixing low-growing herbs in between individual vegetable plants and between rows of tomatoes, potatoes and other crops can further help to throw insects off the trail of potential host plants.

Of course, despite our best efforts, it's normal to experience some losses in the garden. Still, with the right combinations of companion and trap plants, we may not have to share as much of the harvest with insect pests.

Find more articles like this on in Hobby Farms magazine. Pick up a copy at your local newsstand or tack and feed store. Subscribe to Hobby Farms online.