Bulb Hardiness
To lift or not to lift, that is the question many gardeners ask this time of year: Will my elephant ears make it through winter? What about my dahlias, my glads, my cannas? Bulb hardiness depends on many factors: the average winter temperatures in your area, the severity of a given winter, the degree of shelter in your garden, and the species or cultivar. Bulbs are ranked from the most tender (injured below 68 F) to the hardiest (injured below 5 F). The USDA Plant Hardiness Zone Map, which delineates three growing zones for North Carolina (6, 7 and 8), is based on the average minimum temperatures in a region (find your zone at www.ces.ncsu.edu/depts/hort/consumer/ weather/hardiness_zones.html or consult any gardening book).
North Carolina Cooperative Extension provides the following guidelines:
- Cannas may remain in the ground, mulched, in Zones 7 and 8. Lift rhizomes in Zone 6 after first frost, remove soil and store in dry peat or vermiculite.
- Dahlias may overwinter in Zones 7 and 8, with mulch; dig in Zone 6 and store at 35–45 F in dry vermiculite or sand.
- Caladiums do not survive North Carolina winters; dig tubers in fall and store dry at 70–75 F.
- Glads and elephant ears seem to be on the fence in terms of hardiness within Zones 7 and 8. If in doubt, lift gladiolus corms when foliage dies back and store in a mesh bag at 35–41 F to ensure proper air circulation. Dig tubers of elephant ears, dry them and store at 70–75 F.
For more information, consult the plant label, check with the nursery where you purchased the plant, or ask your neighbors about their experiences.