Collard greens are a popular leafy vegetable known for their robust flavor and nutritional value. As members of the Brassica oleracea family, they are susceptible to specific garden pests and require ample nutrients to thrive. Companion planting is a natural technique that involves placing different plant species near collards to create a mutually beneficial environment. This strategy supports the collard plant’s health and productivity without relying on chemical interventions.
The Goals of Collard Companion Planting
The primary goal of companion planting is protecting the crop from specialized insect herbivores. Pests like the cabbage white butterfly and flea beetles locate collards using specific chemical cues. Aromatic companion plants release strong volatile compounds that mask the collard plant’s natural scent, confusing pests and reducing infestation.
A second function is improving the soil environment, as collards are heavy feeders requiring high levels of nitrogen. Legumes contribute to soil fertility by hosting nitrogen-fixing bacteria in their root nodules. This process converts atmospheric nitrogen into a usable form, providing a steady supply of fertilizer.
Beneficial Neighbors for Pest Control and Growth
Tomatoes
Tomatoes are recommended neighbors because their foliage releases compounds, including alkaloids like solanine, that repel brassica-specific pests. Planting tomatoes nearby significantly deters flea beetles, which often chew small “shot-hole” damage into young collard leaves. This repellent effect helps young collard plants establish themselves without early insect pressure.
Aromatic Herbs
Aromatic herbs are effective at scent masking due to their high concentration of volatile oils. Dill, mint, and rosemary release strong odors that interfere with the olfactory sensors of pests like the cabbage moth. Interplanting these herbs creates a protective aromatic barrier that confuses female moths seeking egg-laying sites.
Marigolds
Flowering species like marigolds (Tagetes species) serve a dual purpose. Their roots exude thiophenes, which suppress parasitic nematodes in the soil. Their bright flowers also attract beneficial insects, including hoverflies and parasitic wasps, which prey on common collard pests like aphids and cabbage worms.
Legumes
Leguminous plants, such as bush beans or peas, enhance soil quality. These plants form a symbiotic relationship with Rhizobium bacteria, capturing atmospheric nitrogen and converting it into nitrates. This process naturally fertilizes the surrounding soil, reducing the need for external nitrogen amendments for the heavy-feeding collard plants.
Plants to Avoid Near Collard Greens
Other Brassicas
Avoid planting other members of the Brassica family near collards, including cabbage, kale, and broccoli. These plants share the same pest and disease vulnerabilities, allowing infestations like cabbage worms or diseases like clubroot to spread easily. Placing them together creates a concentrated target for specialized herbivores, increasing the risk of widespread damage.
Heavy Feeders
Heavy-feeding vegetables should be kept separate from collards to minimize competition for resources. Both corn and strawberries require substantial amounts of nitrogen and water. When grown in close proximity, competition for limited soil nutrients often results in stunted growth and lower yields for the collards.
Allelopathic and Root Crops
Aggressive root vegetables and certain aromatic plants can inhibit collard growth through chemical or physical means. Fennel releases allelopathic substances that actively inhibit the growth of many nearby plants. Planting large root crops, such as potatoes, near collards can also cause physical competition below the soil surface.
Intercropping and Timing Strategies
Successful companion planting relies on strategic placement, often utilizing intercropping where companions are planted directly within the collard rows. This close arrangement maximizes beneficial effects, such as scent masking, by placing the protective barrier where it is needed.
Timing the planting is also key to managing garden space. Succession planting uses quick-maturing companions like radishes or lettuce, which are harvested before the collards reach full size. This maximizes early production while suppressing weeds until the collard canopy closes.
Taller companion plants can provide beneficial partial shade in regions with intense summer heat. Planting collards on the eastern side of trellised peas or tall tomato cages protects the greens from the harshest afternoon sun, keeping the soil cooler and reducing the likelihood of premature bolting.