The plant is a climber that grows quickly and has large heart-shaped leaves of up to 1m/3ft in diameter. Flowers appear in summer, in white clusters of 10-20 blooms each. Stems can be trained against a wall or between two strong supports such as trees. Sow the seed in spring and leave it until the weather warms up enough for the seedlings to establish themselves; the young plants can die if the temperature drops too low at this stage.