How to winterize dahlias and cannas

The process for winterizing dahlia and canna tubers is pretty much the same. Here’s what the tubers look like with the large canna on the leeft.

I dig up my tubers round mid November (when they have stopped flowering). When I say ‘I’, what I mean is my my wife digs them up (since I can’t get that low anymore). I usually shake off all the dirt (you can rinse them), then leave them to dry in my shed for a few days or more before storing them in a paper bag. Its important to get any water out of the stem, and you can do this by hanging them upside down.

Lots of people have different methods to store them (wrapped in newspaper or in in dry soil), but. this works for me. Storing them in a paper bag as opposed to plastic allows them to breathe. Make sure the canna tubers are not touching each other, so rot and disease won’t spread.

Dahlias don’t like cold and definatley don’t like wet. A few years ago I left a dahlia in the ground through the wet winter and the tubers rotted, giving off the worst smell I have ever come across in the garden (like human vomit).

Don’t forget to label the bag! Holland Bulb Farms sent me a wrong tuber so I only know the color…. Actually their customer service was great and they emailed back with a store credit as soon as I let them know.

This year I’m experimenting by keeping a couple of dahlia’s in the ground and using these sponge things I got on Amazon. Here in the Pacific North West (zone 8b) you can leave them in the ground and protect the tubers from the cold by adding about 8” of compost (which I have never tried).

Monty Don, (the BBC presenter of Gardeners World) said that he tried this (he lives in southern England, (which is the equivalent of zone 8b) and the results were that the dahlias came up later and had smaller flowers but were otherwise fine. This is appealing to me because I can no longer dig up the tubers without help. I’ll keep you posted on how this experiment goes.

Store them in a cool dark place (I put mine in the basement) till they start to sprout in early spring, then replant them in pots outside. They need to be frost free and ideally between 40-50f but our basement is about 65f and they have been fine. When we first moved into this house 1.5 years ago I accidentally left some dahlia tubers in a paper bag in a very hot tool shed all summer and they withered to very pathetic looking remains.

If you want more detail on dahlias go here.