We should be thinking of getting tuberous dahlias and cannas out of the ground and stored away for winter. It’s certainly up to you, whether or not to save these plants. You could buy new dahlias and cannas in spring, but if you’re in a saving mood, here’s how.
Dahlias need to experience a hard, killing frost before being dug. Taking them out of the ground too early, while still green, results in quick rotting as they haven’t hardened their tissues for winter storage. So after a hard frost or two, when the tops are obviously brown from cold damage, lift the tubers and wash them off with a strong jet of water from the hose (it’s also all right to leave them dry and dirty). Take them inside and set the tubers on newspapers until dry—perhaps overnight. Store them in heavy cardboard boxes (wine boxes from the liquor store are ideal), packed in vermiculite, sand or sawdust. Don’t use any plastic boxes or plastic wrap; the tubers need air circulation. Store the closed boxes in a cool, dark basement.
The tubers can be planted next spring, and large tubers with many sections can be split at that time. Splitting could be done now, but it’s easier in spring when the eye growth is more noticeable. The eyes are located on the main stem, and any sections of tubers with a growth eye can be separated with a sharp knife. But it really is easier in early spring when the eyes are more swollen and prominent.
Storing canna tubers calls for different treatment. They don’t require a hard frost to induce hardening of their tissues, and can be lifted any time that’s convenient for you. My friend Marilyn grows them in large, moveable containers and just cuts the plants down, leaving the tubers in the pots, and carts the whole thing into her basement. In spring, she brings them oudoors, gives them water, and they start growth again.
If you want to lift your canna tubers, just brush off most of the soil and store them in boxes, packed with vermiculite. In spring, you’ll notice activity from growth eyes, and that will show you where divisions can be made. Of course, you don’t need to divide them (except for removing dead bits), and the whole clump can be planted outdoors for a huge display. That would fall into the category of garden big, or go home.
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