Borage (Borago officinalis) is an annual herb recognized by its vibrant blue, star-shaped flowers and slightly hairy foliage. Companion planting involves cultivating different species in close proximity to promote mutually beneficial relationships. When borage is strategically placed near certain vegetables and fruits, it can significantly enhance the health and productivity of the entire garden ecosystem. This utilizes the herb’s specific biological traits to improve soil conditions, deter pests, and increase yields for neighboring plants.
The Functional Role of Borage in the Garden
Borage serves multiple ecological functions, making it a highly desirable companion plant. The flowers are rich in nectar, making the plant a powerful attractant for beneficial insects, particularly honeybees and bumblebees. This high level of pollinator activity is beneficial for the fruit set of many vegetables that require insect assistance. Borage also attracts beneficial predatory insects, such as lacewings, ladybugs, and parasitic wasps. These predators help naturally control populations of common garden pests.
The plant’s deep taproot system allows it to function as a dynamic accumulator, drawing up minerals from the subsoil that shallow-rooted plants cannot reach. Borage foliage contains significant concentrations of minerals, specifically calcium and potassium. When the leaves and stems decompose, either naturally or through “chop and drop,” these accumulated minerals become available in the topsoil for nearby crops. This mineral delivery system can directly address common nutrient deficiencies.
Specific Companion Pairings for Optimal Growth
Borage offers targeted benefits when paired with specific garden plants. Planting borage near tomato plants is effective because the herb’s calcium-rich leaves help prevent blossom end rot, a disorder caused by calcium deficiency. Furthermore, borage is thought to help repel the destructive tomato hornworm, potentially by confusing the pest or by attracting parasitic wasps that prey upon the hornworm.
Strawberries are another common companion that benefits significantly from borage. The herb’s strong attraction to bees ensures a high rate of successful pollination for the flowers, directly leading to increased fruit yield. Gardeners also report that borage can improve the flavor and quality of strawberries, attributed to the trace minerals released into the surrounding soil.
For brassicas, which include cabbage, kale, and broccoli, borage acts as a protective barrier. Its scent and the attraction of predatory insects help to deter the cabbage moths and their larvae, the cabbage worms, which commonly defoliate these crops.
Cucumbers and squash varieties, such as zucchini, rely heavily on insect pollination for fruit production, making them excellent companions for borage. Placing borage plants strategically within or around a squash patch ensures a steady flow of pollinators, maximizing the chance for every female flower to be fertilized. This focus on attracting pollinators is often more impactful for these plants than pest control benefits.
Practical Placement and Plants to Avoid
Successful companion planting with borage requires careful consideration of its vigorous growth habit and size. The herb can grow quite large and sprawling, requiring adequate spacing of 12 to 24 inches to prevent it from shading out its neighbors. Care must be taken not to plant borage directly next to delicate, shade-intolerant, or shallow-rooted crops like lettuce, spinach, or radishes. The plant’s rapid growth and deep taproot can aggressively compete with these smaller vegetables for water and nutrients.
Borage is a prolific self-seeder, readily dropping seeds that germinate the following season, often resulting in numerous volunteer plants. To manage its spread, gardeners should deadhead or harvest the spent flowers before the seeds mature. While borage is compatible with most garden plants, avoid planting it near fennel, which releases allelopathic chemicals that inhibit the growth of nearly all nearby plants. Avoiding competitive herbs like mint and comfrey near borage is also recommended, as one plant may become overly dominant.