Dahlias are beautiful, tender perennials that flower from summer into autumn, providing a long season of colour and interest. They are grown from tubers, which look like a cluster of brown, carrot-like roots joined by the previous year’s dried stem.
After flowering, dahlias start to rot back into the ground and the nutrients from the plant are returned to the tubers, which remain in the ground over winter and start growing again in spring. However, because dahlias are tender they don’t reliably survive British winters. You may be lucky if you live in the south – after cutting back the stems, simply apply a thick mulch at the base of the plant to protect the tubers from frost. But if you live in the north or if you experience a particularly long, cold winter, your dahlia tubers may rot and have to be replaced.
So, while you could take the risk and replace them if they rot, you can guarantee your dahlias getting through winter by digging them up and storing them. Then simply replant them in May, when all risk of frost has passed.
Learn how you can ensure a fabulous display of dahlia flowers for next summer, whatever the weather, in three easy steps.
How to store dahlias
You Will Need
- Garden fork
- Dry compost
- Storage box or container
Dig up your dahlias
Once the dahlia foliage has started to die down, dig all around the clump and lift the tubers with a fork, taking great care not to damage them with the fork spikes. Shake off as much soil as you can. Then, using secateurs, cut down the dahlia stems and compost the leaves.
Rinse the tubers
Use a hose or bucket of water to thoroughly rinse the soil off the dahlia tubers, and then stand the tubers upside down to dry.
Pack the tubers
Once dry, pack your dahlia tubers in a box or pot, and cover them with dry compost (it’s important to ensure the compost is dry, as damp compost could lead to your tubers rotting in store). You can also store dahlia tubers in vermiculite, or wrap them in dry newspaper. Once packed into their pots, store your tubers in a frost-free place, such as under the greenhouse staging, in a dry shed or garage.
If your dahlias are in a warm, sheltered spot in the border and you don’t want to lift them, add a thick layer of mulch for extra insulation in winter.