Dahlia

Start tubers indoors in pots during April, keeping them frost-free at around 15-18 degrees Celsius. Plant out after the last frost, typically late May in southern England or early June further north. Choose a sunny, sheltered spot with rich, well-drained soil. Add garden compost or well-rotted manure before planting. Set tubers 10-15 cm deep. Stake tall varieties at planting time. Water deeply during dry spells, especially once buds form. Feed fortnightly with a high-potash liquid fertiliser from July. Pinch out the growing tip when plants reach 40 cm to encourage branching. Deadhead regularly to prolong flowering. After the first frost blackens the foliage, cut stems to 15 cm. In mild areas, mulch heavily and leave tubers in the ground. In colder regions, lift tubers, dry for a week, and store in slightly damp compost in a frost-free shed.

Pinch out the central growing tip when the plant reaches about 40 cm tall to promote bushier growth and more flowers. Remove side buds if growing for exhibition blooms. Deadhead spent flowers regularly.