Can I Leave Dahlias in Pots Over Winter?

If you have dahlias in the ground and want to overwinter them, you can do so only if the ground is not frozen or has a warm microclimate that allows the tubers to survive. Otherwise, the tubers should be dug up and stored in a cool, dark and dry place.

Alternatively, you can bring potted dahlias indoors to protect them from frost over winter. To do this, wait until after the first frost, then cut them back to about soil level, and store in a cool (but not freezing) place such as your basement or garage.

Once inside, it is important to keep the tubers from drying out as much as possible and to prevent them from shriveling and rotting. You can do this by storing them in a box of packing material such as pet bedding or sawdust, or by using a mixture of vermiculite and perlite. The box should be large enough to allow air circulation without allowing moisture to build up on the surface and cause rot.

A squishy, soft or oozy root is a sign that the tuber has rotted and should be removed. If the roots look shriveled and dried out, they are likely still viable but need to be given water so that the tubers can start growing again next spring.

To overwinter your dahlias in the ground, you will need to lift them and dig up the tuberous roots at the end of October or November if they are grown in a cold area. Once you have removed the tubers, if they appear to be rotten or have severe damage, discard them and start with fresh ones.

You can also overwinter dahlias in a greenhouse. But this method is not recommended for gardeners with low temperatures and long cold spells in winter because the tubers can freeze if they are not protected by the greenhouse roof or another barrier.

The best way to overwinter dahlias is by storing them in a cool, dry place that does not freeze and keeping them out of the sunlight as much as possible. This is best done in a garage, shed, or in a basement but you can also put them on the patio if you have one.

Once stored, it is a good idea to cover the tubers with tarps to protect them from the weather. This can be done with old billboards, silage tarps or construction tarps that are water-tight. It is a good idea to weight down the tarps with sand bags or rocks so that they can’t droop and expose the dahlias to the winter sun and wind.

At Love ‘n Fresh Flowers, we have been able to leave dahlias in the ground without digging them up over five seasons now and they have continued to thrive. It is best to do some dividing in order to increase the number of plants, but if you prefer not to, you can always use cuttings and plant them out again later.