Is canna lily a perennial?
Cannas (*Canna* × *generalis* hybrids and species) are tropical perennials that survive in the ground year-round in USDA zones 8–11. In zones 3–7, the rhizomes are killed by freezing soil temperatures and must be dug each fall and stored indoors. In zone 7a Long Island (my zone),
Canna lily occupies the same practical category as dahlias and tuberous begonias — technically perennial, but requiring winter storage in most of the US. Understanding this distinction will save you money and help you build an expanding collection over the years.
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What cannas actually are
Cannas are not true lilies — the "lily" in the name refers to the bold tropical foliage and showy flowers, not botanical relationship. Per Missouri Botanical Garden, the garden canna (Canna × generalis) is a "tender rhizomatous perennial" native to tropical and subtropical regions of the Americas and Asia. The rhizome (a thick, fleshy horizontal underground stem) is the storage organ that allows the plant to persist year after year when protected from frost.
USDA zone behavior
Per University of Florida IFAS, cannas are "perennials in USDA zones 8–11 and annuals in zones 3–7."
Zones 3–7 (most of the US, including the entire Northeast, Midwest, and mountain West): Cannas must be dug before frost and stored through winter. The rhizomes are damaged and killed when soil temperatures drop below 28–30°F. In zone 7 Long Island, the first killing frost typically arrives in late October. I dig canna rhizomes in the first week of October — before frost, after the foliage begins to show the first signs of cold stress (darkening, slight wilting). I don't wait for frost to hit first, as frost damage can lead to rot during storage.
Zone 8 (Atlanta, Charlotte, Dallas): In most winters, cannas can be left in the ground with a 3–4 inch layer of mulch over the rhizomes. But a hard winter in zone 8 (temperatures below 20°F) can kill unprotected rhizomes. Experienced zone 8 gardeners often dig the largest, most valued rhizomes as insurance while leaving some in the ground.
Zones 9–11 (Gulf Coast, California, Hawaii): Cannas grow as true perennials without any special protection. They die back to the ground in a frost (rare in these zones) but regrow vigorously in spring. In zones 10–11, they may grow nearly year-round.
How to dig and store canna rhizomes
Per University of Minnesota Extension, the steps for overwintering in zones 3–7:
- After the first light frost (which blackens the foliage), cut the stems to 3–4 inches above the soil.
- Dig carefully with a garden fork. Rhizomes spread horizontally and can extend 18 inches from the main clump. Avoid stabbing them with the fork.
- Shake off excess soil but do not wash.
- Cure for 1–2 weeks in a single layer in a cool, dry, airy location out of direct sun.
- Store in slightly damp peat moss or sawdust in a breathable container (paper bag, cardboard box, crate) at 40–50°F. Per University of Minnesota Extension, "temperatures below 40°F may injure rhizomes; above 55°F may cause premature sprouting."
- Check monthly for rot (soft, wet spots) or desiccation (shriveling). Remove any rotted sections; mist lightly if rhizomes are shriveling.
- Replant in spring after last frost, when soil temperatures reach 60°F. Per Missouri Botanical Garden, cannas planted in cold soil grow slowly and may rot.
In my zone 7a beds, I store cannas in a cardboard box in the basement, which stays around 45–50°F. They reliably survive this treatment, and I typically divide the clumps each spring as the rhizomes multiply, building up my collection over time.
Starting cannas: rhizomes vs. transplants
Most garden centers sell cannas as potted transplants (already started, ready to plant) or as dormant rhizomes in bags. Rhizomes are cheaper but require a longer lead time.
Rhizomes: Soak rhizomes in warm water for 12–24 hours before planting to break dormancy. Per University of Minnesota Extension, plant "2–3 inches deep with the growing eye (bud) facing up." In zone 7, start rhizomes indoors in pots 4–6 weeks before last frost to get a head start on the season; transplant outdoors after last frost.
Transplants: Set out after last frost once soil has warmed to 60°F. No cold hardening is needed — cannas have no frost tolerance.
Size and cultivar considerations
Cannas range from dwarf types (18–24 inches) to giants (6–8 feet). Per Missouri Botanical Garden, flower colors include red, orange, yellow, pink, and bi-colors. Foliage is also variable — most are green, but 'Tropicanna' and similar cultivars have striking bronze or striped leaves.
For zone 7 gardeners who store rhizomes every year, compact cultivars are easier to handle and store than 6-foot giants. My preference for the vegetable garden border is a mid-height type (3–4 feet) that doesn't shade the adjacent beds.
Common mistakes
| Mistake | What happens | Fix |
|---|---|---|
| Planting in cold soil | Slow growth, possible rot | Wait for 60°F soil temps |
| Not digging before hard frost | Rhizome damage, loss | Dig before first frost in zones 3–7 |
| Wet storage conditions | Rhizome rot | Store in barely damp (not wet) medium |
| Deep planting (6+ inches) | Delayed or no emergence | Plant 2–3 inches deep only |
| Zone 7 gardeners leaving in ground without mulch | Rhizome loss | Either dig or mulch heavily (4+ inches) |
Frequently asked
Can I leave cannas in the ground in zone 7?
It's a gamble. Zone 7 is right at the borderline — if the winter is mild (not much below 20°F), heavily mulched rhizomes sometimes survive. Per Missouri Botanical Garden, mulching with "4–6 inches of protective mulch" after the ground cools is recommended for zone 7 "in situ" storage. But a hard winter will kill them, so most zone 7 gardeners (myself included) choose to dig reliably rather than gamble.
How do I divide canna rhizomes?
Each growing season, canna rhizomes multiply significantly. When dividing at replanting time, look for natural break points between sections. Per University of Minnesota Extension, each division should have "at least one healthy eye (bud)." A sharp knife or hatchet makes clean cuts; dust cut surfaces with garden sulfur to reduce rot risk.
Are cannas deer-resistant?
Mixed reports. Per Rutgers NJAES, cannas are listed in the "occasionally severely damaged" category — deer will browse them when other food is scarce but do not preferentially target them. In my zone 7a Long Island beds with high deer pressure, I've seen deer damage canna foliage during dry summers when other food sources are limited.
Why are my canna leaves full of holes?
The most common culprit is the canna leafroller, a caterpillar that rolls and staples leaf edges together. Per NC State Extension, the damage is "unsightly but rarely serious." Unrolling affected leaves reveals the caterpillar; remove by hand. Per UC IPM, Bt (Bacillus thuringiensis (BT spray)) sprays applied to the affected areas can provide control.
Sources
- Missouri Botanical Garden — Canna × generalis
- University of Minnesota Extension — Cannas
- University of Florida IFAS — Canna
- NC State Extension — Canna Leafroller
Sources
- 1. Missouri Botanical Garden — *Canna × generalis*
- 2. University of Minnesota Extension — Cannas
- 3. University of Florida IFAS — Canna
- 4. NC State Extension — Canna Leafroller