Storing Dahlias over winter

Unlike canna and hedychium, dahlias are best dug up soon after the frost has destroyed the foliage. Although they can be left in the soil over winter with a protective mulch, they are more likely to rot during a particularly wet winter.

Dahlia tubers being washed prior to winter storage.

Washing dahlia tubers prior to storage

Another thing to consider is that left in the ground, your dahlias will not be producing flowers until much later in the summer. Left in the ground your emerging shoots will be at the constant mercy of passing molluscs. Slugs and snails will shear the shoots to ground level leaving you with the sense that all your Dahlias died over winter. The silver linning, if you manage to get control of the situation, is that your dahlia will then throw up many more stems.

You may of course simply wish to grow them in an other location. Digging up dahlia tubers also allows you to increase your stock through division and cuttings.

When cutting back the foliage on your frosted dahlias, leave a few inches of stem so you can easily locate the tubers before digging them up. There is no need to panic about getting them out of the ground once the frost has been, but they become increasingly hard to locate if all the stems have been removed.

Dig them up with a garden fork, taking care not to skewer the tubers. Don't put the fork in too close and go nice and deep to get under the tubers. If your soil is nice and friable they should lift out easily.

Wash them

Before storing dahlias for winter they need to dry out. A good place to do this is on a greenhouse bench, this can be in full sun. Make sure the tubers are upside down for this phase ie the stems downwards. This allows any water collected to drain out. Once fully dry the tubers are ready for storage.

Storing dahlia tubers in a wire mesh laundry device.

Traditionally before storing dahlias for winter, the tubers would have been dusted with a fungicide and stored in paper bags or boxes of dry peat. However the tubers will survive perfectly well without fungicide, if stored dry, in a well ventilated place and not piled on top of each other. A good device for storing dahlias is a wire mesh laundry contraption such as this. (Available from all good Swedish furniture manufactures)

The odd tuber may still rot but generally your stock of dahlias can be increased quite easily. Propagating Dahlias tubers by division or taking cuttings helps you to do this.