What Are the Best Companion Plants for Butternut Squash?

Butternut squash is one of the three crops in the traditional Native American "Three Sisters" planting — along with maize and beans — a combination where each plant benefits the others. Beyond this classic combination, a range of companion plants can improve pollination of squash flowers, deter common pests, make use of the ground shaded by the large squash leaves, and add colour and biodiversity to the growing area. Understanding which plants work well alongside squash — and which should be kept separate — helps you get more from your growing space.

Flowers to attract pollinators

Borage is considered by many the ideal squash companion — it flowers prolifically, its star-shaped blue flowers are highly attractive to bumblebees, and it is said to deter tomato hornworm and aphids. Marigolds (especially French marigolds, Tagetes patula) repel aphids and whitefly and attract hoverflies whose larvae eat aphids. Nasturtiums are easy to grow and act as a trap crop for aphids — they attract aphid colonies that might otherwise settle on the squash. All three can be planted around the edges of the squash bed.

The Three Sisters combination

The Three Sisters — squash, maize, and climbing beans — is a time-tested planting combination. The maize grows tall and provides a support for the climbing beans. The beans fix nitrogen from the air and enrich the soil. The squash spreads its large leaves along the ground, suppressing weeds and retaining soil moisture. Each plant occupies a different layer and different niche, making very efficient use of space and nutrients. This combination can be adapted to a modern garden on a smaller scale.

Plants to avoid near squash

Potatoes are generally best kept well away from squash — they compete vigorously for nutrients and water, and share some pest and disease pressures. Other cucurbits (cucumbers, courgettes, other squash and pumpkins) will cross-pollinate with butternut squash — this does not affect this year's fruit, but saved seeds from cross-pollinated plants will produce mixed results. Fennel is known to inhibit the growth of many vegetable plants, including squash, and should be sited away from the vegetable garden.