Dahlias are tuberous perennials from Mexico that flower from July until the first frost. They are not hardy in Central Europe, so tubers are started in pots indoors in April and planted outside in mid-May, after the last frost, about 10 cm deep. They need full sun, rich, well-drained soil and regular watering in summer; feed with a potassium-rich fertiliser once buds form. Put a stake in at planting time – tall varieties can reach 1.5 m and snap in wind or heavy rain. Pinching out the growing tip once plants have three or four pairs of leaves makes them bushier. Cut flowers for the vase in the cool of the morning and remove faded blooms regularly to keep new buds coming. Slugs damage young shoots and earwigs chew the petals. After the first frost blackens the foliage, cut the stems to 10 cm, lift the tubers, let them dry and store them in a dark, frost-free place at 4–8 °C.