Dahlias come in a range of different sizes. The dwarf varieties can be grown as bedding, while more compact varieties grow very well in pots, while Tree dahlias (Dahlia imperialis), from which all modern dahlias were bred, can reach 5m tall.
Dahlias make brilliant and prolific cut flowers – the more you cut them, the more flowers they produce. Because of their complex flowers, most dahlias are not attractive to pollinators.
They like plenty of sunshine to thrive and are tender – they need protection in winter. Dahlias require a fertile, moist but well-drained soil, and a sunny, sheltered spot. The taller varieties need staking. In autumn, dig up the tubers and overwinter them in a frost-free place, such as a greenhouse or a shed. Bring them back into growth in early April, then plant out in the garden from May onwards.