Marigolds (Tagetes spp.) are renowned for their vibrant blooms and pest-repellent properties, making them excellent companion plants. From a plant's perspective, their root exudates and aromatic foliage create a symbiotic environment that benefits neighboring plants by deterring harmful insects, suppressing soil nematodes, and attracting pollinators.
Tomatoes (Solanum lycopersicum) thrive alongside marigolds due to their mutual benefits. Marigolds release alpha-terthienyl, a compound that repels root-knot nematodes, which commonly attack tomato roots. Additionally, marigolds attract hoverflies and ladybugs, natural predators of aphids that plague tomato plants. The marigold's scent also masks the tomato's aroma, reducing pest detection.
Cucumbers (Cucumis sativus) benefit from marigolds by experiencing fewer attacks from cucumber beetles and aphids. Marigolds act as a trap crop, luring pests away from cucumbers. Their dense foliage also provides slight shade, helping cucumber plants retain moisture in hotter climates.
Beans (Phaseolus vulgaris) and marigolds form a mutually beneficial relationship. While beans fix nitrogen in the soil, marigolds protect them from soil-borne pests like Mexican bean beetles. The marigold's root exudates also improve soil health, indirectly supporting bean growth.
Roses (Rosa spp.) paired with marigolds experience fewer aphid infestations and fungal issues. Marigolds deter rose pests like thrips and attract beneficial insects such as lacewings. Their antifungal properties may also reduce the risk of black spot disease in roses.
Brassicas (e.g., cabbage, broccoli, kale) benefit from marigolds' ability to repel cabbage moths and whiteflies. The strong scent of marigolds confuses pests, reducing egg-laying on brassica leaves. French marigolds (Tagetes patula) are particularly effective against root-feeding nematodes.
Herbs like basil (Ocimum basilicum) and thyme (Thymus vulgaris) grow well with marigolds. The marigold's pest-repellent properties reduce herb damage, while some gardeners report enhanced flavor in basil when grown nearby. Marigolds also attract pollinators, boosting herb seed production.
Squash (Cucurbita spp.) and melons (Cucumis melo) benefit from marigolds' ability to repel squash bugs and striped cucumber beetles. The bright flowers also attract pollinators, improving fruit set in these crops.
Strawberries (Fragaria × ananassa) paired with marigolds experience fewer slug and nematode issues. Marigolds improve soil structure and microbial activity, creating a healthier root environment for strawberries.
Alliums (e.g., onions, garlic) and marigolds work synergistically to repel pests. While alliums deter aphids and carrot flies, marigolds protect them from soil nematodes. This combination creates a robust pest barrier in the garden.
