Below I discuss how to store canna bulbs. By extension, you can use this information for storing other tropical or sub-tropical plants that return annually via bulbs or rhizomes.
Note: The instructions I supply can be considered the by-the-book method. The fact is, my wife stores cannas down in an unheated basement during the winter without preparing them at all (she leaves the bulbs in the pot they grew in all summer) and without giving them any water all winter.
Canna bulbs (technically, rhizomes, but known to the general public as canna "bulbs") can be left in the ground to overwinter in planting zones 8-11. In zones colder than that, to be safe, it's best to dig and store canna bulbs at the end of fall. When winter is over, the ground has thawed and all danger of frost has passed, you'll be able to plant your canna bulbs again outside.
How to Store Canna Bulbs
- When: Although you could dig up the canna bulbs earlier, most growers wait until the cannas' foliage has been killed by frost.
- Remove any foliage -- dead or alive -- from the canna bulbs.
- Note: In storing canna bulbs, there is some disagreement among the experts as to whether you should remove the dirt from the canna bulbs, or let it stay on.
- Allow the canna bulbs to dry for a few days inside before storing, where they won't freeze.
- You'll be storing the canna bulbs in a plastic bag, in which you can punch some small holes, for aeration.
- Put peat moss in the bag to retain some moisture.
- Now pack the canna bulbs in the peat moss, in such a way that no two of them touch.
- Store the canna bulbs in a dry, dark cool place (around 50 degrees, give or take a few degrees).
- Periodically check during the winter to make sure the peat moss around the canna bulbs is still slightly damp (if you find it dry, use a mister to dampen it).
You might wonder why, in the above steps for storing canna bulbs, I mentioned the need both for moisture and dryness. Isn't that a contradiction? Well, the point is to strive for a balance. Too much moisture will rot the canna bulbs; while not enough moisture will cause dessication. Avoid either extreme.