Ipomoea is a large and diverse genus consisting of about 500 species. The best-known garden plants are climbing annuals and tender perennials - the genus name is from the Greek ips, "worm," and homoios, "resembling" - but the genus also contains nonclimbing annuals and perennials along with a few shrubs and trees. Botanists have classified and reclassified the plants contained here, so several species are still listed under other names. Closely related to Convolvulus species, Ipomoea species bear funnel- or bell-shaped flowers, either singly or in clusters in the leaf axils. Hummingbirds are attracted to the blooms, especially of red-flowered species and cultivars.

A site in full sun and average, well-drained, evenly moist soil is ideal. Most require strings, a trellis, or other support upon which to climb.

Sow seeds indoors in individual pots 6 to 8 weeks before the last spring frost date. Germination takes from 1 to 3 weeks at 18° to 22°C.

Seedlings will need a stake to climb on even when they are still fairly small, otherwise, the vines will become entangled. Transplant a few weeks after the last frost once temperatures remain above 7°C. or sow outdoors 2 weeks after the last frost date

Install the required trellis before outdoor sowing. Either way, to speed germination carefully nick the seedcoat with a knife or file and/or soak the seeds for 24 hours in warm water before sowing. In addition to seeds, perennials can be propagated by cuttings taken in spring or summer, which can be used to overwinter the plants, if desired.

Some of the hardier species can be obtained from nurseries such as Ipomoea learii, which seems to be the hardiest of the tropical types we can grow in Britain (see below).

Use these plants to climb and cover all manner of structures from deck railings and fences to trellises. They also can be trained over shrubs. Some, including foliage cultivars of I. batatas, are effective clambering among perennials and annuals in mixed plantings or in containers.

Here are some suitable species to try for next summer outdoors or in the conservatory.

Ipomoea alba
Moonflower. A tender perennial climber that can reach 15 feet in a single season. Large, rounded leaves with heart-shaped bases. Bears fragrant, white 5- to 5 1/2-inch-wide flowers that open at dusk from early to midsummer to frost. The flowers attract night-flying moths.

Ipomoea batatas

Sweet Potato.
A tender perennial grown in food gardens for its fleshy, sweet, edible roots. Plants can climb or spread 10 feet or more in a single season, and to 20 feet or more in frost-free climates. They bear rounded to heart-shaped leaves that can be entire or lobed and 1-inch-wide, pale purple flowers in summer. While even cultivars developed for vegetable gardens have attractive foliage, often flushed with purple, several are grown for their leaves alone: 'Blackie' bears dark, purple-black, maple like leaves; 'Margarita' has chartreuse, heart-shaped leaves; 'Pink Frost' has arrow-shaped leaves marked with green, white and pink, which require protection from direct sun. All are hardy in very mild coastal gardens and produce tubers, which can be dug before frost and overwintered like a dahlia. Tender perennial.

Ipomoea coccinea

Red Morning Glory

A vigorous 6 to 12-foot annual climber with ovate or deeply toothed leaves. Bears small clusters of scarlet, 3/4-inch-wide trumpets in summer. Warm-weather annual.

Ipomoea lobata
Spanish Flag. Formerly Mina lobata
A tender perennial climber most often grown as an annual that ranges from 6 to 15 feet in height. Bears lobed leaves and dense, one-sided racemes of slightly curved, narrow, tubular flowers that are 1/2 to 3/4 inches long. Buds and flowers initially are red but turn orange, yellow, and then cream as they age. 'Citronella' bears lemon yellow flowers that age to white.

Ipomoea learii

Indian Ipomoea

A hardy perennial exotic climber with large dark navy blue typical morning glory flowers and large lobed leaves.

Grows very fast to 20 feet, requires full sun. Best grown on a sunny south facing wall or fence.

Mulch roots in winter

Hardy in Western Cornwall.