Flowers control garden pests by attracting beneficial insects. As part of companion planting for organic gardeners, adding specific flowers near vegetable and flowering plants helps control garden pests without the use of toxic chemicals. Desirable beneficial insects include lacewings, ladybugs, hoverflies, parasitic wasps, tachinid flies, praying mantis and predatory bugs. Two plant families offering excellent garden pest control are the Compositae and Umbelliferae.
Black-eyed susans are members of the Compositae flower family with bright yellow petals and black centers. They grow well in full sun and tolerate some shade, especially in very hot climates. They are often seen growing wild along roadways. Black-eyed susans bloom in summer and early fall, and the plants are between one to two feet tall. The flowers attract lacewings, ladybugs and parasitic wasps.
Marigolds make a lovely bright yellow border plants for your garden. Scented marigolds, particularly French and African varieties, discourage white flies, and some marigolds release compounds that are toxic to selected species of nematodes. There is anecdotal evidence that marigolds discourage tomato hornworms. Marigolds are also members of the Compositae flower family. Plant them in direct sun and well-drained soil.
Zinnias are members of the Compositae (also called aster) family--the largest group of flowering plants in northern latitudes. Not only are zinnias great for attracting beneficial insects, they add vibrant colors to your garden in pinks, oranges, whites and salmon. Zinnias are easy to grow from seed and prefer direct sunlight for at least six hours per day. Native to the southwest and Mexico, your zinnias require some supplemental water to thrive. Zinnias also attract pollinating insects like bees and butterflies.
Queen Anne’s Lace
Queen’s Anne’s Lace is a member of the Umbelliferae family, also known as the parsley or carrot family. Members of the Umbelliferae family have compound umbels--stems of the flower radiate from a single point at the end of the stalk. The plant’s small white flowers with purple centers attract lacewings, ladybugs and hoverflies.
Queen Anne’s Lace is a biennial plant that grows in height in its first year, producing flowers in its second. It blooms throughout the summer except in the hot south where it blooms in the spring. Queen Anne’s Lace can be found growing wild over much of the northern United States.