A cultural practice with roots in antiquity, companion planting, involves planting two or more kinds of plants in close proximity. Its popularity spiked in the 1970s when organic gardening began to attract a wide audience, and now companion planting is being applied to roses to keep them healthy without the need for insecticides.
Native Americans have doing companion planting in their gardens for eons using three compatible crops: corn to support the pole beans, pumpkins to spread across the ground as a living mulch and beans to fix atmospheric nitrogen via symbiotic bacteria living in root nodules. When their corn seedlings reach about 6 inches tall, they sow several pole bean seeds in every hill of corn and a few pumpkin seeds in every seventh hill.
This technique lets you maximize the use of garden space, improve pollination and obtain better plant growth when mutually beneficial plants are combined. It was featured in Louise Riotte’s best-selling book titles, such as “Roses Love Garlic” and “Carrots Love Tomatoes.”
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Repelling insect pests is a common reason given for companion planting. Although results can be mixed, it is said garlic repels aphids, wormwood repels flea beetles and marigolds repel insects, in general.
Attracting insects to your garden is much more important than repelling them. Companion planting is the way to establish a diverse population of insects where beneficial species, such as ground beetles, lacewings, lady bugs, parasitic wasps, tachinid flies and praying mantis can find food, cover and opportunities to reproduce.
A new rose garden at Canada’s Royal Botanical Garden has “3,000 roses and 18,000 perennials chosen as insect attracting companions,” according to its designer Peter Kukielski. The author of the recently published book, “Rosa: The Story of the Rose,” was featured last February in The New York Times, where he advised gardeners to select regionally adapted rose varieties, use mulch and leaves instead of fertilizer and embrace companion planting.
Highly recommended are members of the carrot family with their tiny flowers clustered in uplifted umbels. One of the best is dill, which attracts many predators and parasites of insects while also self- sowing year after year and it tastes good on potato salad.
Other members of this family are parsley, anise, angelica, chervil, caraway, cilantro (coriander), cumin and fennel. Another good one is Queen Anne’s lace or wild carrot.
More top choices for planting with your roses are the daisy-like flowers of the composite family of plants. These include cosmos, purple coneflower (Echinacea), gloriosa daisy (Rudbeckia), sneeze weed (Helenium) and fall blooming chrysanthemum and aster.
Many other native plants are magnets for insects. They range from butterfly weed and penstemon to phlox and golden rod.
Native grasses also provide valuable habitat for insects. The best ones are Indian grass, switch grass, little blue stem and big blue stem.
Praying mantises will stalk your rose garden for prey when you practice companion planting. In autumn, they will attach their nut-size brown egg cases to the stems of those grasses.
Don Davis is a retired Virginia Cooperative Extension agent. He can be reached at dodavis2@vt.edu.
