Thunbergia

These tender vines are natives of tropical Africa, South Africa, tropical Asia and India. These plants are usually treated as annuals, though they will behave as perennials in mild climates. They will grow 3 to 15 feet long. The ovate to triangular leaves grow up to 4 inches long and they produce flowers that may grow solitary or in clusters. They look like flaring tubes, 1 to 2 inches across. They may be orange, yellow, or white, with or without a brownish-purple eye.

Pot Cultivation

These plants love well-drained moist soil and sun half the day or more. When they are grown in a greenhouse, they may be planted (in March) in pots or tubs, but the best results will come from planting in a bed of soil in the greenhouse. Take out 2 feet of soil and add 6 inches of broken crocks, broken bricks, stones, or crushed gravel in the bottom for drainage. Cover that with rough leaves or similar material to prevent the soil from washing down. Fill the rest of the space with two parts good topsoil, one part peat moss or leaf mold and well decayed manure, with a bit of sand. Once the plant is set down, pat the soil firmly and don't water until it becomes fairly dry, after which it is thoroughly watered. Throughout the summer, the soil should be kept moist and the atmosphere humid. Watering should gradually be reduced as autumn approaches and during mid-winter, the soil is kept fairly dry. When the plants start to grow actively during the summer, dilute liquid fertilizer should be applied. It is beneficial to sprits the foliage, except when they are in bloom and on cold winter days. The plants should be cut back quite harshly in the spring. Prune back all shoots and train the main branches to a trellis or greenhouse wall.

Propagation

Start seeds inside at a 70- to 75-degree temperature, 6 to 8 weeks before it's safe to plant outside. They should be sown in a pots or seed pans filled with light, finely sifted soil. Sprinkle them thinly on the surface and cover lightly with soil and a glass pane. They may also be sown outside where they are to grow when the soil is warm. Cuttings may be made, in the spring, from young side shoots that are about 3 inches long. Insert these in sand, sand and peat moss, or vermiculite in a propagating case in a warm greenhouse and when they've formed roots, they are potted individually in small pots and treated as if they were seedlings.