With a new round of vegetable gardening for fall in full swing, August is a good time to take a second look at “companion planting.”
The most familiar example is planting marigolds in vegetable beds to repel harmful insects. Unfortunately, science offers little support for that particular pairing. Planting French marigolds from the garden center with your broccoli or lettuce doesn’t hurt, but it won’t do much to discourage bug attacks, either.
Surprisingly, though, a North Carolina researcher has found that pretty much the opposite strategy – planting plants to attract insects, not repel them – brings real benefits to gardens and landscapes.
In 2007, Debbie Roos of the N.C. Cooperative Extension Service began creating a series of demonstration pollinator gardens. One is at the Executive Mansion in Raleigh, where former North Carolina Gov. Bev Perdue harvested honey from hives near the garden and current first lady Ann McCrory hosted a garden tour last spring, which also featured the governor’s large vegetable garden.
Roos’ flagship garden, the “Pollinator Paradise,” is at Chatham Mills in Pittsboro. This garden contains 154 species of trees, shrubs and perennial flowers, most of them native to North Carolina. She also planted a number of important non-native herbs and flowers.
Roos designed the garden to provide habitats for pollinators such as honeybees, native bees, butterflies, flower flies, beetles and other beneficials. It also attracts hummingbirds, other birds and wildlife.
Bees and other pollinators are vital to fruit and nut crops, such as apples and almonds. Without them, we wouldn’t have watermelons for summer picnics or pumpkins for Halloween. There are growing concerns, however, that many pollinators – not just European honeybees, but native species as well – are threatened. Pollinator gardens offer a refuge for these unsung heroes.
The diverse population of plants in Roos’ garden provides additional benefits, such as nurturing insects that prey on pests.
Dr. Linda Chalker-Scott, a garden myth-buster, compares “marigold-style” companion planting to comic page horoscopes – entertaining, maybe, but not sound advice. She is quick to add, however, that observation and research clearly demonstrates plant diversity (she prefers the ecological term “plant associations”) can help attract and retain beneficial insects.
In addition, a number of different plants growing together can disorient pest insects, especially ones that attack and breed on a specific kind of plant.
Practical implementation of a diversity plan for a food garden or landscape remains part science and part art, with dozens of factors to take into account – including root size and growth rate. A relatively easy first step is to simply create a separate natural habitat area, as Roos has done. The Charlotte Observer’s Nancy Brachey suggests starting with an area where grass and conventional landscaping are not doing well.
The Pollinator Paradise garden has yet another benefit worth noting: It is beautiful in all seasons, with the charm and color of a natural meadow vibrant with wildflowers. Roos’ captivating collection of photos on her website reveals some of the lovely, but odd and extraordinary, creatures that call the garden home.
The pollinator garden is at 480 Hillsboro St., Pittsboro. It is open to the public for informal visits seven days a week, and Roos offers a free guided tour once a month.
Roos’ excellent website, Growing Small Farms ( http://growingsmallfarms.ces.ncsu.edu), has a wealth of reliable information about pollinator gardening, sustainable agriculture and a host of other topics of interest to gardeners and growers.