Kale (Brassica oleracea) is a resilient, cool-season leafy green vegetable and a member of the cabbage family. Gardeners often use companion planting, the practice of growing specific crops near each other, to foster a healthier, more productive garden ecosystem. This method relies on natural interactions to achieve mutual benefits, such as enhancing growth or improving soil conditions. Companion planting for kale involves selecting neighbors that deter common pests, attract beneficial insects, or manage soil nutrients. The right pairings can significantly reduce challenges, transforming a simple plot into a robust environment.
Plants That Deter Pests and Improve Kale Health
Companion plants for kale primarily work by confusing or repelling insects that target the Brassica family. Aromatic herbs are excellent choices because their strong scents mask kale’s natural odor, making it difficult for pests like the cabbage moth to locate the leaves. Planting herbs like dill and cilantro nearby can attract beneficial insects, such as hoverflies and parasitic wasps, which prey on destructive pests like aphids and cabbage worms. Alliums, including onions and garlic, are effective because their sulfur compounds naturally repel aphids and flea beetles from the foliage.
Flowers serve a dual purpose, acting as decoys or attracting natural predators. Nasturtiums, with their lily-pad-like leaves, function as a “trap crop,” luring aphids and flea beetles away from the kale and providing a sacrifice plant for these common pests. Conversely, flowers like sweet alyssum and marigolds attract beneficial insects, such as ladybugs and lacewings, whose larvae are predators of soft-bodied insects like aphids. Marigolds also release a chemical from their roots that can help suppress soil-dwelling nematodes, which can damage plant roots.
Root crops and legumes contribute significantly to kale’s soil health. Kale is a heavy feeder, needing nitrogen for prolific leaf growth. Bush beans and peas are legumes that enrich the soil by fixing atmospheric nitrogen through bacteria in their root nodules. Crops with different root depths, like carrots and beets, are ideal companions because they do not compete with kale’s shallow root system for surface nutrients and water. Root vegetables like radishes also help break up compacted soil, improving drainage and aeration for kale’s roots.
Crops to Keep Separate From Kale
Certain plants should be avoided near kale because they share the same vulnerabilities or compete too aggressively for resources. All other members of the Brassica family, including broccoli, cabbage, cauliflower, and Brussels sprouts, should be spaced far away. They are all susceptible to the same pests, such as flea beetles and cabbage loopers, and planting them together can lead to an overwhelming infestation. Grouping these crops also rapidly depletes the soil of specific nutrients, most notably nitrogen, due to their high feeding requirements.
Heavy-feeding crops that require significant amounts of nitrogen and other nutrients can stunt kale’s growth due to intense competition. Tomatoes, for example, are vigorous growers that compete directly with kale for soil resources and water, resulting in a diminished harvest for both plants. Similarly, strawberries and kale both demand rich soil and can attract pests like slugs, which can then spread between the crops.
A few specific herbs and vegetables can actively inhibit kale’s development. Fennel releases chemicals that suppress the growth of many neighboring plants, including kale, making it a poor choice for intercropping. While pole beans are nitrogen fixers, their aggressive climbing habit can quickly overshadow the kale, blocking sunlight and reducing air circulation, which invites fungal diseases. Maintaining separation from these plants preserves soil health and reduces pest and disease pressure.
Maximizing Garden Space with Companion Planting
Successful companion planting with kale involves strategic spatial arrangement and timing. Intercropping, which means growing two or more crops in close proximity, maximizes limited garden space and pest deterrence. Aromatic plants like chives or scallions can be tucked directly between kale plants, providing a continuous pest-repellent scent barrier. Planting a dense border of marigolds or sweet alyssum around the kale patch creates a protective perimeter that attracts beneficial insects into the growing area.
Timing the planting of companions can also optimize resource use through succession planting. Fast-maturing crops, such as radishes or lettuce, can be planted alongside young kale seedlings and harvested before the kale grows large enough to require the full space. This method provides an early harvest and ensures the soil is utilized during the kale’s initial, slower-growth phase. Once the early crop is removed, the kale has access to the full nutrient profile and space for its mature size.
Vertical gardening elements can be integrated by using taller plants to provide necessary microclimates for the cool-season kale. In warmer periods, planting tall crops like sunflowers or corn strategically on the south or west side of the kale can offer light afternoon shade. This shade mitigates heat stress that can cause the leaves to wilt or become bitter. This layering technique optimizes light exposure and temperature, allowing the kale to thrive throughout its long growing season.