Connecticut Garden Journal: How to dig up and store dahlias and cannas for the winter
Our dahlias and cannas have been tremendous this year with the warm fall weather. But frost has finally put them to rest. Now it's time to dig and store them for winter because dahlias and canna lilies aren't hardy in our climate.
To store them, cut the foliage to ground level. Then carefully dig up the entire clump of dahlia and canna lilies to inspect them before storing. Gently knock off the soil around the tubers, remove damaged tubers and label each variety. Let the clumps dry in a dark, cool, airy place, such as an unheated garage or shed, for a few days. Then wash off more soil before storing them.
Some gardeners like to divide clumps in fall, but I'd rather wait until spring. Dahlias and canna tubers have eyes that sprout into new shoots. Not all tubers will have eyes. In fall it may be hard to tell where the eyes are, but by spring they will start swelling like on a potato. Then you'll know which tubers to keep.
I store dahlia and canna tubers in cardboard boxes. I fill my boxes with wet wood chips to keep the tubers moist, but with good airflow. Other gardeners use slightly moist peat moss or vermiculite as well. Place the boxes in a cool, dark basement or garage where the temperatures stay between 35 and 50 degrees. Check periodically in winter. If the tubers have shriveled or dried out, mist them. If the tubers have started to rot, dry them out. By spring you should have plenty of tubers to plant and share with friends and family.