Family: Tropaeolaceae
Common Name: Nasturtium

With distribution from Chile to Mexico, these annuals and perennials are grown for their brightly coloured flowers, from pale yellow and orange through to deep red. Of the 90 species, most have a climbing, spreading habit. Nastur­tiums contain a fragrant mustard oil used as a seasoning, while the flowers are added to salads for decoration. The leaves are used as a green salad vegetable, and flower buds and unripe fruits can substitute for capers.

Species

Hybrids of T. majus, the annual garden nasturtium, zone 10, are bushy or trailing plants. The many named cultivars have bright, summer flowers in red, orange, yellow or cream, and either double or single. The dwarf cultivars are the most popular with gardeners and are freely available. A dwarf form with var­iegated foliage and flowers in mixed colours has been bred and is known as Alaska Series. Well worth growing if available.

T. peregrinum, canary creeper, zone 9, grows to 2.5 m (8 ft) high, with lobed, gray-green leaves and rich yellow, fringed flowers.

T. speciosum, flame nasturtium, zone 8, is an herbaceous, perennial climber, to 3 m (10 ft), with long, spurred scar-let flowers.

T. tuberosum, zone 8, from Peru, has tuberous roots and cupshaped, orange and yellow flowers.

Cultivation

Nasturtiums will grow in almost any soil, although an over-enriched soil encourages foliage growth rather than flowers. T. peregrinum, however, requires a rich soil. Plant either in full sun or semi-shade and water frequently. Propagate from seed. Annual garden nasturtiums are sown in mid-spring, outdoors where they are to flower. Seed of perennials is best sown, as soon as ripe, in a garden frame.

Climate

There are species suited to various cli­matic zones.