storage of Cannas and Dahlias - Ask Extension
What is the best procedure for digging up cannas and dahlias to keep for next year?
Knowledgebase
storage of Cannas and Dahlias #890107
Asked November 20, 2024, 5:56 PM EST
What is the best procedure for digging up cannas and dahlias to keep for next year?
Anne Arundel County Maryland
Expert Response
Some gardeners in central and southern/eastern MD have luck with cannas and dahlias overwintering in the ground in mild areas, but it may be safer to dig and store them just in case they are not hardy enough. Cannas can be dug up now (if they weren't already) and stored in either a cool, dry basement, cellar, garage, or shed at about 50° to 55°F. Avoid temperatures below 45°F or above 70°F. Don't store them bare-root (with the soil removed) as the tubers can dry out. Alternatively, a U.S. Botanic Garden plant breeder has had success digging them up and putting them in a crate or pot with some potting soil to fill-in around the rhizome, and then layering 3 to 4 inches of mulch on top; put the containers where they receive sun in the winter.
Once dahlia tubers have been dug out of the ground, you only need to let them cure (air-dry) for a day or two. If left out longer, they may begin to dry out and shrivel up. When you first dig out the tubers, the outer skin is very tender and thin (can be easy to nick with a fingernail). When they are cured, the surface of the tuber is a little bit darker and tougher. Visually, the difference can be somewhat subtle.
There are advantages to rinsing the tubers (some people blow off the soil instead of using water). This gets out any clumps of soil that might be holding a lot of moisture and microorganisms next to the tubers - potentially leading to rotting in storage. Rinsing off the clump also makes it easier to divide the tubers (if you plan to do so in the fall).
You can trim off roots and thin tubers as soon as you dig the clumps out of the ground. You also can trim away the “mother” tuber (it usually has a rougher surface and may even be shriveled or partially hollow -- it will not regrow).
If you are interested in dividing tubers, it could be done in spring or fall, though most commercial dahlia growers divide in the fall. The tubers are more tender and easier to cut when they are freshly dug out (whereas after winter storage, they are toughened-up and larger clumps can be more difficult to cut). Also, dividing the tubers in the fall can make it easier to store them. That said, there is absolutely nothing wrong with storing whole clumps and making divisions in the spring. Either way will work, and it comes down to personal preference.
The American Dahlia Society has excellent instructions on dividing tubers and the various options you can use for storing them for the winter: Digging, Dividing, and Storing Tubers. They also have a guide demonstrating how to process (rinse and divide) tubers.
Miri
Once dahlia tubers have been dug out of the ground, you only need to let them cure (air-dry) for a day or two. If left out longer, they may begin to dry out and shrivel up. When you first dig out the tubers, the outer skin is very tender and thin (can be easy to nick with a fingernail). When they are cured, the surface of the tuber is a little bit darker and tougher. Visually, the difference can be somewhat subtle.
There are advantages to rinsing the tubers (some people blow off the soil instead of using water). This gets out any clumps of soil that might be holding a lot of moisture and microorganisms next to the tubers - potentially leading to rotting in storage. Rinsing off the clump also makes it easier to divide the tubers (if you plan to do so in the fall).
You can trim off roots and thin tubers as soon as you dig the clumps out of the ground. You also can trim away the “mother” tuber (it usually has a rougher surface and may even be shriveled or partially hollow -- it will not regrow).
If you are interested in dividing tubers, it could be done in spring or fall, though most commercial dahlia growers divide in the fall. The tubers are more tender and easier to cut when they are freshly dug out (whereas after winter storage, they are toughened-up and larger clumps can be more difficult to cut). Also, dividing the tubers in the fall can make it easier to store them. That said, there is absolutely nothing wrong with storing whole clumps and making divisions in the spring. Either way will work, and it comes down to personal preference.
The American Dahlia Society has excellent instructions on dividing tubers and the various options you can use for storing them for the winter: Digging, Dividing, and Storing Tubers. They also have a guide demonstrating how to process (rinse and divide) tubers.
Miri
