The practice of companion planting involves strategically placing different plant species near strawberries (Fragaria x ananassa) to achieve mutual benefits. Selecting the right partners enhances the health, yield, and sometimes the flavor profile of the fruit. This ecological approach optimizes growing conditions, creating a more resilient and productive environment with less reliance on external chemical inputs.
Mechanisms of Strawberry Companion Planting
The success of companion planting relies on ecological principles that influence the strawberry patch’s micro-ecosystem. Pest management is achieved through chemical signaling and scent masking, as aromatic plants release volatile compounds that confuse or deter pests.
Flowering companions also serve as biological control agents by attracting beneficial insects. These include pollinators, necessary for fruit set, and predators like ladybugs, lacewings, and parasitic wasps. The presence of these predators naturally manages common strawberry pests such as aphids and mites.
The root systems of complementary plants improve soil health and nutrient availability. Some plants fix atmospheric nitrogen into a usable form, providing a natural nutrient source for the strawberries. Diverse root depths utilize soil resources more efficiently and improve soil structure, leading to better water infiltration and drainage.
Beneficial Plant Groupings
Herbs
Many herbs offer protective benefits to strawberry beds due to their strong scents. Borage, with its distinctive blue flowers, attracts pollinators and beneficial predatory insects such as braconid wasps. This herb is also believed to add trace minerals to the soil, potentially contributing to sweeter fruit.
The Allium family, including chives, onions, and garlic, acts as a powerful pest deterrent. The sulfur compounds released repel common strawberry pests like slugs, snails, and aphids. Chives, in particular, help suppress fungal diseases like Fusarium wilt in nearby crops.
Aromatic herbs like thyme and sage serve a dual purpose. Thyme is a low-growing plant that works as a living mulch, suppressing weeds and retaining soil moisture around the shallow strawberry roots. Sage emits strong odors that confuse or repel flea beetles and other crawling insects.
Vegetables
Certain vegetables are excellent companions because they occupy different ecological niches, minimizing competition. Lettuce and spinach are ideal because their shallow roots do not compete with strawberries for nutrients and water. They also provide a living ground cover that shades the soil, keeping the root zone cool and moist.
Spinach provides an added benefit by producing saponins, natural compounds that may offer antifungal and antibacterial properties in the soil. Bush beans are valuable companions as they host nitrogen-fixing bacteria in their root nodules. This process naturally enriches the soil with nitrogen, benefiting the fruiting plants, and bush beans repel certain strawberry-feeding beetles.
Flowers
Flowering plants contribute significantly to pest management and pollination. Marigolds (Tagetes species) are widely used because some varieties, particularly French marigolds, release root compounds toxic to root-knot nematodes. The strong scent of the flowers also deters various above-ground pests.
Nasturtiums function as a trap crop, drawing pests like aphids and whiteflies away from the strawberries. They also attract beneficial insects and feature a trailing habit that provides ground cover. Calendula attracts predatory insects like hoverflies and lacewings, which feed on soft-bodied pests.
Plants That Inhibit Strawberry Growth
Some plants should be kept far away from strawberries because they hinder growth or increase disease risk. The nightshade family (Solanaceae), including tomatoes, potatoes, peppers, and eggplants, shares a high susceptibility to Verticillium wilt, a soil-borne fungus. Planting strawberries in soil recently occupied by these crops greatly increases the risk of infection, as the fungus can persist for years.
Plants with aggressive growth habits or allelopathic properties also make poor neighbors. Fennel releases chemical compounds that inhibit the growth of surrounding plants, including strawberries. Mint, while aromatic, is an extremely vigorous and invasive grower, quickly overwhelming and competing with strawberries for space and nutrients.
The Brassica family (cabbage, broccoli, kale) are heavy nutrient feeders that aggressively compete for soil resources, especially nitrogen. Their dense foliage can also cast too much shade over the low-growing strawberries. Additionally, large, vining crops like squash and melons compete heavily for moisture and reduce the light needed for robust fruit production.
Layout and Rotation Strategies
Effective companion planting requires thoughtful spatial arrangement to maximize benefits and prevent competition. Low-growing herbs like thyme and spinach are best interplanted directly between the strawberry crowns, acting as a living mulch. Taller plants, such as bush beans, should be positioned to the north of the patch to prevent excessive shading.
Deterrent plants like chives and marigolds are most effective when planted as a border around the perimeter, creating a protective barrier against crawling pests. In a permanent strawberry patch, which lasts three to four years, surrounding companion plants should be rotated annually. This rotation prevents the buildup of pest populations and soil-borne diseases.
While strawberries are perennials, establishing new patches in a different location every few seasons ensures long-term soil health. When starting a new bed, gardeners should avoid areas where Verticillium wilt-susceptible crops were grown in the previous five years. This strategic rotation and placement maintains the integrity of the soil and the health of the plants.