Companion planting involves growing different plant species close together for mutual benefit. This technique is valuable when cultivating cabbage, a member of the Brassica family, because these heavy feeders rapidly deplete soil nutrients. Cabbage is also highly susceptible to common garden pests, including the destructive cabbage worm and flea beetles. Strategically placing certain neighbor plants helps manage these challenges naturally, reducing the need for chemical interventions. The right companions can deter harmful insects, enhance soil quality, and lead to a more successful harvest.
Companion Plants for Pest Management
Many common garden pests target cabbage, but aromatic herbs and certain flowers offer defense. The primary strategy involves confusing pests by masking the distinct odor of the cabbage plant. Cabbage white butterflies and moths are repelled by the strong scents of herbs like rosemary, thyme, and dill, preventing them from laying eggs that hatch into cabbage worms.
Alliums, such as chives, garlic, and onions, are effective due to their pungent, sulfur-containing compounds. Planting these throughout the cabbage patch creates a chemical barrier that deters a wide array of insects, including aphids and slugs. This strong aroma makes it difficult for pests to locate the cabbage host plant. Geraniums also deter major pests like cabbage worms.
Some companion plants work by diverting pests away from the cabbage entirely, acting as a “trap crop.” Nasturtiums are a classic example, as aphids prefer to feed on their foliage rather than the cabbage leaves. Marigolds are beneficial, known for repelling nematodes in the soil and deterring above-ground pests like cabbage worms and flea beetles. They also attract beneficial insects, such as hoverflies, which prey on aphids.
Companion Plants for Growth and Soil Health
Beyond pest deterrence, specific companion plants contribute to cabbage growth and soil fertility. Cabbage requires significant nitrogen to develop its large, dense head, making nitrogen-fixing plants valuable partners. Legumes, including bush beans and pole beans, harbor bacteria in their root nodules that convert atmospheric nitrogen into a usable form, fertilizing the cabbage as they grow.
Other plants act as a living mulch to regulate the soil environment. Low-growing crops like lettuce, spinach, or clover can be planted between cabbage plants to cover the soil surface. This cover suppresses weed growth, reducing competition for water and nutrients. It also keeps the soil cooler and retains moisture, which benefits the shallow root systems of cabbage.
Root vegetables with different growth habits can also improve soil structure. Beets and celery have different root zones and nutrient requirements, so they do not compete directly with the cabbage’s shallow roots. Beets help break up the soil, and celery may enhance the flavor of nearby cabbage. Plants with deep taproots, like borage, are dynamic accumulators that draw up nutrients and minerals from deep in the soil, making them available to the shallower-rooted cabbage as their leaves decompose.
Plants to Avoid Next to Cabbage
While many plants offer mutual benefits, some neighbors can harm a cabbage crop through intense competition or shared disease susceptibility. Cabbage is a heavy feeder, and planting it alongside other crops with high nutrient demands, such as corn or tomatoes, leads to competition for resources. Tomatoes and their relatives in the Solanaceae family may also release substances that inhibit cabbage growth, a phenomenon known as allelopathy.
Plants within the same Brassica family, like broccoli, cauliflower, or kale, should be spaced away from cabbage. These plants share nutrient requirements and are susceptible to the same pests and diseases, such as clubroot. Planting them together creates a monoculture effect that rapidly spreads disease and concentrates pest pressure.
The onion family, including garlic and leeks, presents a complex case; while they repel pests, some gardeners report they can slow the development of the cabbage head due to released compounds. Another plant to avoid is fennel, which releases chemical compounds that inhibit the growth of many other garden vegetables, including all cruciferous crops. Strawberries are also poor companions, as they compete for nutrients and can harbor pests like the cabbage looper.