Thanks to Sharon Carothers for this timely info!
Canna tubers very seldom will survive our winters. So each fall, after the greens have been blackened by frost, gardeners can dig up the tubers for storage over the winter. Here’s the process of saving and dividing canna tubers for next spring.
After the first killing frost, the greens of cannas and other tender bulbs will blacken and it is time to dig them up:
•Cut back the tops of the cannas to three to four inches. Loosen the soil around the cluster of tubers. A garden fork, a sunny day and dry soil make the job fairly easy.
•Turn the clumps over and allow the tubers to dry for several days or longer, possibly a couple of weeks if they are moist, but be sure to move to a covered area if rain is in the forecast. Or hose them off and put them somewhere where they can dry completely for a week or two.
•Carefully dust off the loose soil. They must be dry.
•Locate the eyes on each tuber. Eyes are the buds, like the eyes on a potato.
•With a sharp, clean knife, divide the tuber into sections so that each section has at least two eyes. One eye may work but I prefer to err on the side of caution. Place the cut side up so that the air allows it to form a dry scar.
TUBERS MUST BE COMPLETELY DRY TO BE STORED.
•Dust the tubers with fungicide if you have problems with rotting during storage, if your storage area is not ideal, or just to protect from fungus during the winter.
•Store in a box of peat moss, vermiculite or sand. Keep the container open or punch holes in it to allow air circulation. Others recommend storing on shelves, racks, or mesh bags to allow air circulation. I personally have found the most success by taking a cardboard box; putting a couple of layers of newspaper in the bottom and then wrapping the dried tubers in a sheet of newspaper and putting them into the cardboard box. When full put a couple of layers over the entire lot and close the lid.
•Store the containers in a cool (temperatures below 50 degrees) but frost-free area, dark and dry.
In mid to late March unwrap the tubers and place them in pots about 1-1/2 – 2 sizes bigger than the tuber with a little damp potting soil in the bottom. Throw away any that have rotted. Cover the tuber in more damp potting soil with the eye pointed up but covered in soil. Be sure the soil is not wet. The pots to not need sunlight at this point. (I put them on the floor in an unfinished area of the basement). Check weekly to see if you can see any growth (can take several weeks). As soon as you do; add more soil to the top of the pot (covering the growth). Once leaves grow move the pot to a sunnier location and commence watering and fertilizing program. You may have to up-pot if they get too large before you can put them outside (after frost).