Most plants in the genus Plectranthus that are familiar to northern gardeners are small house plants valued for their colorful aromatic leaves. Being in the mint family, they have square stems and opposite leaves. Large spur-flower looks very different: a large shrub native to forest margins and streams of South Africa, grown for its huge sprays of blue-purple flowers that from a distance resemble lilacs. Each floret is a long tube that flares out with swept-back petals, revealing the long stamens. It is only hardy to Zone 8, but it can be grown in northern climates and set outside during the summer. The flowers will bloom in September and October, attracting pollinators. Before frost, it will need to be brought inside and cut back.