Dahlias are not winter-hardy
As soon as the first night frost arrives, it's time to protect your dahlias from the real winter. Dahlia tubers are not winter-hardy. They can’t handle frost, they freeze and die. If the soil stays too wet, they may also rot or become mouldy.
How to overwinter dahlias
If you want to enjoy your dahlias again next year, it’s a good idea to follow a few simple steps:
- Wait a few days after the first frost before digging them up. The leaves and stems will blacken and die back, and all the plant’s energy will move down into the tubers. This gives the tubers the best chance to survive storage over winter. If autumn is very wet and water doesn’t drain within a day, it’s better to lift the tubers already from mid-October.
- Cut the stems down to about 30 centimetres above the ground. You can use this stem later as a handle when lifting the tuber. Use a garden fork to loosen the soil around the plant – about 30 cm away from the stem and gently lift the clump out of the ground.
- Label each tuber with its name and, if you like, the colour and plant height. That way you can easily plan your garden again next year.
- Let the tubers rest for a few hours in a sheltered spot with the stems pointing down, so any trapped water can drain out.
- Brush off the soil using an old dish brush or a soft paintbrush. You can trim away excess roots if needed.
- Before storing, inspect each tuber carefully. Are they healthy and firm? If any show signs of rot, damage or mould, it’s better to discard them.
- Cut the stems shorter for easier storage and to prevent mould.
- Store your tubers in wooden crates or boxes with ventilation holes. It’s important to have good air circulation without exposing them to drafts, which can dry them out. Everyone has their own method. Some store their tubers in dry sand or used potting soil, others use straw, wood shavings or wrap them in newspaper. Choose the method that works best for you. Place the crates in a cool, frost-free spot, like a crawl space under the house, as long as it’s not too damp. The ideal temperature for storage is between 6 and 9 degrees Celsius.
It takes a little effort, but you’ll be rewarded with blooming, healthy dahlias again next summer.
You can also overwinter dahlias in pots. Keep them under a shelter to prevent the tubers from getting wet. Make sure the pots are stored in a frost-free place. Once the weather warms up in spring, you’ll see new shoots appear. You can then divide the clumps with a sharp knife and replant them in the garden.
Leaving dahlias in the ground
If all this sounds like too much work, you can take the risk and leave the tubers in the ground. In a mild winter, and depending on your soil and location, they might survive. Cover them with a thick layer of compost or straw as a warm blanket. If the winter turns out to be too harsh, you can always treat yourself to new dahlia tubers in our dahlia candy shop.
A fresh garden every year
There’s actually a big advantage to lifting your dahlias each year. It gives you the chance to redesign your garden with fresh colours and new varieties. One year you might go for a cheerful garden with yellow and pink dahlias, and the next for a romantic look with red and white ones.
There are so many stunning combinations to try. We love pairing the dinnerplate dahlia Belle of Barmera with the smaller ball dahlia Sylvia. Belle of Barmera is big and bold in soft pink, while Sylvia brings warm orange tones and a perfect shape to balance the mix.
Looking for inspiration? Try one of our ready-made dahlia mixes, carefully matched in colour and height for a beautiful result.
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