Companion planting is the technique of interplanting vegetables, herbs or flowers in close proximity for the benefit of the different species. The benefits include providing natural pest control, increasing yield and attracting beneficial insects. Without companion planting, plants may become dependent on herbicides and pesticides, whereas with interplanting of herbs and flowers, insects and birds are attracted as natural predators to harmful insects.
For best results, plant strawberries in well-drained soil in full sun and out of the wind. The plants grow successfully in a wide range of soil types from light sand to heavy clay, but should not be planted in soil where tomatoes, peppers, eggplant and potatoes have been grown in recent years. Placing netting over the plants prevents birds and squirrels from eating the fruit. Strawberries are not harmful to most plants, but they are invasive and can become prolific, depleting nutrients that other plants may need.
Borage is a hardy annual that is used as a culinary herb and in herbal remedies. The plant is useful as a companion plant for strawberries to strengthen resistance to insects and disease. Borage deters harmful pests and attracts predatory insects, such as the praying mantis and wasps. Bees are attracted to borage, which increases pollination of strawberry flowers and increases future crops. Borage improves soil nutrition by adding trace elements to the soil.
Comfrey keeps the soil rich and moist and improves the size and flavor of strawberries. Use thyme as a border to deter worms and attract bees and predator insects. Caraway, planted throughout the garden, loosens soil and attracts wasps and flies that are predators of strawberry pests. Marigolds produce a strong odor that deters insects and slugs. A substance in the roots of marigolds deters nematodes that can destroy a strawberry crop.
Strawberry plants are compatible with a number of vegetables. Beans add nitrogen, fertilizing the soil naturally for a better strawberry yield. Lupine is a legume that also adds nitrogen to the soil and attracts honeybees. Strawberries can be interplanted successfully with spinach or lettuce. Strawberries should not be interplanted with vegetables in the cabbage family, including cabbage, Brussels sprouts, broccoli, kohlrabi or cauliflower.