The idea of companion planting is as old as agriculture itself. Farmers have observed through the ages that certain vegetables just seem to grow better when planted together; in recent years, this has become one of the accepted ways of enhancing an organic garden. Companion plants cut down the need to add fertilizer or use pesticides in the garden, and that’s a good thing.
Not as well known, though, are the effects of planting flowers among the beans, squash and corn. Some purists want to keep vegetable gardens solely for vegetables, but there are a number of flowers that you can to plant next to your edibles that will improve your yields and draw off insect pests.
And speaking from personal preference, I find the combination of vegetables and flowers very attractive in a yard.
One flowering plant that has been the object of scientific study is tansy, an herb that produces masses of yellow flowers. Tansy in large-scale studies has been shown to attract ladybugs, lacewings and other beneficial insects that prey on aphids. In addition, according to a study by the Rodale Institute Research Center in Pennsylvania in the 1990s, interplanting tansy with potatoes reduced Colorado potato beetles by 60 to 100 percent.
Other beneficial flowering plants in the Rodale study included the “White Sensation” variety of cosmos, and herbs such as caraway, dill and fennel.
In the classic book “Designing and Maintaining Your Edible Landscape,” author Robert Kourik recommends planting dandelions with tomatoes, since apparently the dandelions excrete a compound that protects against fusarium wilt. Another is amaranth, which is thought to keep leafminers away from bell pepper plants.
Most famous since early times is the effect of marigolds, which have a pungent odor that could be responsible for keeping bugs away. In Europe, marigolds are often used as an edging for cottage gardens, according to the book “Old Wives’ Lore for Gardeners,” by Maureen and Bridget Boland, and they are said to be beneficial to any kind of vegetable. It’s also thought that excretions from their roots kill nematodes in the soil. French marigolds are most commonly used, although Mexican or African varieties also are recommended by some gardeners.
Nasturtiums are also said to benefit the growth of cucumbers, and their blossoms are edible and beautiful, and make a colorful topping for salads. Dwarf zinnias and sweet alyssum are also noted by the Organic Gardening Web site for attracting ladybugs and beneficial wasps.
Two other flowers recommended in the Borlands’ book are foxglove and chamomile. Their observations in their own garden are that these plants act as “doctors” for other plants and somehow make them grow better.
“Designing and Maintaining Your Edible Landscape,” book by Robert Kourik
“Old Wives’ Lore for Gardeners,” book by Maureen and Bridget Boland