Borage (Borago officinalis) is another all-round performing companion plant for cannabis grows. Borage improves the health of cannabis plants as it naturally enhances the soil with vitamins and minerals. Borage is quite hardy and will thrive in most conditions. It shows continuous sprays of tiny lavender colored flowers all throughout the growing season. This companion plant attracts bees and predatory wasps which repel or hunt unwanted creatures like cabbage worm and whitefly larvae from your cannabis garden. This companion plant takes sun or part shade and prefers moist soil.