How to Naturally Control Aphids on Brussels Sprouts

Inspect each brussels sprout plant before transplanting it to your garden bed. Because many aphid infestations begin in seedling beds, thoroughly inspecting seedlings before the plants are moved to the garden can be a good method for cultural control of aphids.

Plant ornamental plants in borders and nearby planting beds to attract beneficial insects such as ladybugs, lacewings and other insects that prey on aphids. For example, planting bachelor's buttons (Centaurea cyanus), which are hardy in U.S. Department of Agriculture (USDA) plant hardiness zones 3 through 8 , can help attract ladybugs, beneficial wasps and lacewings to your garden. Other plants that attract natural enemies of aphids include annuals such as sweet alyssum (Lobularia maritima) and perennials such as golden marguerite (Anthemis tinctoria), which is hardy in USDA zones 3 through 7.

Grow aromatic herbs nearby. Examples include tansy (Tanacetum vulgare), which is hardy in USDA zones 4 through 8; catnip (Nepeta cataria), hardy in zones 3 and 4; and basil (Ocimum basilicum L.), hardy in zones 9 through 11. Although little supporting scientific evidence exists, many gardeners believe these plants, which typically are grown as annuals by many gardeners, repel aphids. Growing tansy and catnip in containers can help prevent the herbs from taking over a garden and becoming invasive.

Spray infested brussels sprout plants with a strong stream of water early in the day. The spray reduces the number of aphids on the plants. When dislodged from a plant, most aphids aren't able to go back to the plant. Spraying the plants early in the day allows the plants enough time to dry before sunset, preventing fungal diseases.

Apply an organic insecticide such as neem oil, a natural product that contains azadirachtin, which causes aphids to feed less frequently and slows their growth. Mix roughly 2 tablespoons of neem oil in 1 gallon of water, and use the solution to spray every surface of the plants. Apply it once every one to two weeks as soon as you spot the first adult aphids on your brussels sprouts.