Overwintering dahlias is worth doing correctly to ensure that next year you can again enjoy the colourful blooms. Dependant on whereabouts you live your dahlias are probably looking pretty untidy by now. There may still be the odd bloom hanging on but the plants will have lost all signs of vigour and life. But, it’s still too soon to cut them down!
The first fronts will blacken the dahlia stems and foliage and at this stage they can be cut down. Cut the stems to ground level and add them to the compost heap. The next step in overwintering dahlias depends very much on where you live and on your soil.
If you live in the warmer parts of the south and have well-drained soil, then your dahlia tubers will be fine left in the ground. You will still need to cut them down but then just cover with a deep mulch of garden compost.
However, if you live in colder parts of the country and/or have heavy, clay soil then your dahlia tubers will need lifting. They can then be stored over-winter and replanted in the spring.
Lifting & Storing
– Use a fork to carefully lift the tubers from the soil being careful not to damage them.
– Allow the tubers to dry and then remove any soil and trim off any thin roots.
– Stand the tubers upside down in a shallow box or tray for a few weeks. This will allow any residual moisture to drain away.
– Turn the tubers the right way up and place them in trays.
– Cover the tubers with dry soil or sand but leave the crowns clear and exposed.
– Place some newspaper over and store in a shed or other cool but frost-free place.
– Check the tubers from time to time and throw away any that show signs of rot.
Once spring arrives and the danger of frost has gone the tubers can be planted out. Choose a sunny spot and plant the tubers at a depth of 10 to 15cm. Then apart from staking, feeding and watering just sit back and wait for those stunning blooms.