Climbing and bush nasturtiums make sunny companions for spring and early-summer bloomers such as dahlias, lilies, and roses. Their vivid orange-to-yellow flowers seem to glow in garden beds, even on foggy days. They're ideal for covering banks, fences, and tree stumps, and easy to start from seed; plus, their leaves add peppery flavor to salads. Left to their own devices, nasturtiums will reseed in mild climates and are likely to wander and show up in surprising places. Although their loose arrangement of leaves and flowers gives gardens a casual, cottagey look, these prolific annuals can also be contained: Simply remove unwanted plants as soon as blossoms begin to fade and before seeds set. Flowers are best in full or part sun.

Sow seeds now in mild winter areas; water regularly if rain doesn't come.