Marigolds + Melons
Certain marigold varieties control nematodes in the roots of melon as effectively as chemical treatments.
Tomatoes + Cabbage
Tomatoes are repellent to diamondback moth larvae, which are caterpillars that chew large holes in cabbage leaves.
Cucumbers + Nasturtiums
The nasturtium's vining stems make them a great companion rambling among your growing cucumbers and squash plants, suggests Sally Jean Cunningham, master gardener and author of Great Garden Companions. Nasturtiums "are reputed to repel cucumber beetles, but I depend on them more as habitat for predatory insects," such as spiders and ground beetles.
Peppers + Pigweed
Leafminers preferred both pigweed and ragweed to pepper plants in a study at the Coastal Plains Experiment Station in Tifton, Georgia. Just be careful to remove the flowers before the weeds set seed.
Cabbage + Dill
"Dill is a great companion for cabbage family plants, such as broccoli and brussels sprouts," Cunningham says. "The cabbages support the floppy dill," while the dill attracts the tiny beneficial wasps that control imported cabbageworms and other cabbage pests.
Corn + Beans
The beans attract beneficial insects that prey on corn pests such as leafhoppers, fall armyworms and leaf beetles. And bean vines climb up the corn stalks.
Lettuce + Tall Flowers
Nicotiana (flowering tobacco) and cleome (spider flower) give lettuce the light shade it grows best in.
Radishes + Spinach
Planting radishes among yor spinach will draw leafminers away from the spinach. The damage the leafminers do to radish leaves doesn't prevent the radishes from growing nicely underground.
Potatoes + Sweet Alyssum
The sweet alyssum has tiny flowers that attract delicate beneficial insects, such as predatory wasps. Plant sweet alyssum alongside bushy crops like potatoes, or let it spread to form a living ground cover under arching plants like broccoli. Bonus: The alyssum's sweet fragrance will scent your garden all summer.
Cauliflower + Dwarf Zinnias
The nectar from the dwarf zinnias lures ladybugs and otherpredators that help protect cauliflower.
Collards + Catnip
Studies have found that planting catnip alongside collards reduces flea-beetle damage on the collards.
Strawberries + Love-In-A-Mist
Tall, blue-flowered "love-in-a-mist (Nigella damascena) looks wonderful planted in the center of a wide row of strawberries," Cunningham says.