If you have an empty area in your garden that you will eventually plant with perennials, or an ugly fence that needs some quick color, nasturtiums (Tropaeolum tuberosum) may be just what you have been looking for.
Nasturtiums are often grown as annuals, but in many parts of the Bay Area they can be grown as perennials. Herbaceous vines twine and climb to 12 feet, or cover the ground with mounds of bright green leaves and cup-shaped orange, pink, burgundy or yellow flowers. Nasturtiums bloom most heavily in spring and summer, but in some microclimates they can be seen blooming in winter. They are easily grown from seed, or can be purchased in 6 packs for a quicker cover.
A relative of watercress, nasturtiums are edible, both the leaves and flowers making a tasty addition to salads and other cold dishes.
Most varieties can survive when grown in partial sun. In fact, they will produce lush foliage but then you tend to miss the best part of your nasturtiums: they flower less under those conditions. Ideally, nasturtiums like to be in full sun, with moist, well drained soil. Once they are established, nasturtiums will continue to spread and bloom, reseeding easily on their own.
Nasturtiums basically come in two forms: compact and trailing. The compact variety is low and busy, usually staying at about 12″ tall. They are useful as border plants, creating a colorful and dense edge. The trailing variety cascades dramatically down walls or tumbles brightly out of hanging baskets. They are also perfect for window boxes and container herb gardens. Just be sure to keep them trimmed back or they will crowd out the other plants.