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.
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