Overwintering Canna The President bulbs is essential in regions with freezing temperatures (such as USDA hardiness zones 6 and below), as they are not frost-tolerant. Before the first frost, cut back the foliage to about 6 inches above ground level. Carefully dig up the rhizomes, shaking off any excess soil, and let them dry for a day or two.
Store the rhizomes in a cool, dark, and well-ventilated area, ideally at temperatures between 40-50°F (4-10°C). Place them in a box or container filled with peat moss, sawdust, or vermiculite to prevent them from drying out. Check periodically for any signs of mold or rot and remove affected rhizomes.
If you live in USDA hardiness zones 7 and up, it is fine to leave the cannas in the ground over winter. Just make sure to give an extra layer of mulch in colder months.