How to Overwinter Canna Lilies

Cannas are tropical plants pretending to be hardy perennials, and how you overwinter them depends entirely on your USDA zone. In zone 8 and warmer, you can leave them in the ground under a heavy mulch and they will resprout in spring. In zone 7 and colder, the ground freezes deep enough to kill the rhizomes, so you lift them after the first frost, dry them off, and store them cool, dark, and barely damp until the soil warms again. Either way the plant survives winter as a fat, knobby underground rhizome — a swollen horizontal stem packed with growth buds — and your job is simply to keep that rhizome from freezing, rotting, or drying to dust.

A single canna planted in spring bulks up into a dense colony of rhizomes by fall, so overwintering is also how you multiply your stock for free. Lift one clump in October and you can have three or four plants the next May. The process is forgiving — cannas are tougher in storage than dahlias — but a few details make the difference between plump rhizomes that explode out of the pot in spring and a box of shriveled or moldy disappointment. This guide covers both the lift-and-store method for cold climates and the mulch-in-place method for warm ones, with the temperatures and timing that keep cannas alive.

Know Your Zone: Lift or Leave?

Before you touch a shovel, figure out which strategy your climate calls for. Cannas are hardy in roughly USDA zones 8 through 11, meaning the rhizomes survive winter in the ground there. In zones 8 and 9, especially toward the colder edge, leaving them in place works but benefits from a protective mulch. In zone 7 and any colder region, winter soil temperatures drop low enough to kill the rhizomes outright, so lifting and indoor storage is the only reliable way to keep them. Microclimates matter too — a south-facing bed against a heated wall in zone 7 may overwinter cannas that would die in an exposed bed across the yard.

If you are right on the zone 7/8 line and want to hedge your bets, lift half your clumps for safe indoor storage and mulch the other half in the ground. That way a hard winter cannot wipe you out, and a mild one rewards you with established plants that come up early. Container-grown cannas are the easiest of all: in cold zones, just move the whole pot into an unheated but frost-free garage or basement, cut the foliage back, and let the soil go nearly dry until spring.

The Mulch-in-Place Method (Warm Zones)

In zones 8 and warmer, overwintering cannas is almost effortless. After the first frost browns the foliage, cut the stalks back to 2 to 6 inches above the ground. Then pile on a thick insulating mulch — 4 to 6 inches of shredded leaves, straw, bark, pine needles, or compost — spread over the root zone to buffer the rhizomes against the occasional cold snap and to keep the soil from heaving during freeze-thaw cycles. In the coldest part of zone 8, you can go heavier, up to a foot of loose mulch, and pull it back in spring once hard frosts have passed so the new shoots are not smothered.

The one enemy of in-ground cannas is not cold so much as waterlogged winter soil, which rots the rhizomes. If your beds stay soggy through winter, improve drainage before relying on the mulch method, or lift the rhizomes despite living in a “hardy” zone. Even where cannas overwinter happily in place, it is worth digging and dividing the clumps every two or three years, because crowded rhizomes bloom less and flower size shrinks as the colony competes with itself.

Lifting Canna Rhizomes (Cold Zones)

In zone 7 and colder, wait for the first frost to blacken the foliage — that cold snap signals the plant to move its energy down into the rhizomes and begin dormancy. Once the leaves have been frosted, cut the stalks down to about 4 to 6 inches, leaving short stubs as handles. Then dig a wide circle well outside the stem, because canna rhizomes spread aggressively and you do not want to slice through them. Lever the entire clump up with a garden fork, lifting from underneath rather than pulling on the stalks, which can tear the rhizomes apart at their joints.

Do not wait so long that the ground freezes solid — frozen rhizomes are dead rhizomes. In most cold regions the window is mid to late autumn, often within a week or two of that first killing frost. Once the clump is out, gently knock and shake off the bulk of the soil. You do not need to wash cannas; a coating of dry garden soil is fine and actually helps buffer moisture in storage. Cannas grow from rhizomes rather than bulbs, which changes how they store and divide — our comparison of rhizomes vs bulbs explains why these knobby, multi-eyed stems behave so differently from a tulip or daffodil.

Drying and Storing the Rhizomes

After lifting, let the clumps dry. Set them in a cool, airy, frost-free spot out of direct sun — a garage, shed, or basement — for a few days up to a week so the cut surfaces and any nicks dry and callus over. This curing step seals out the rot organisms that would otherwise move in during the long months of storage. You want the outside dry to the touch while the rhizomes inside stay firm and plump; cannas hold moisture better than dahlias, so over-drying is less of a worry, but you still do not want them sitting damp.

Once dried, pack the clumps in barely-damp peat moss, sawdust, wood shavings, sand, or shredded paper, nestled in cardboard boxes, paper bags, or vented plastic bins. The packing medium buffers humidity so the rhizomes neither dry to husks nor sit wet against one another — squeeze the medium and it should clump but release no water. Store them in a cool, dark place at 45 to 55°F, such as an unheated basement, a frost-free garage, a root cellar, or a closet on an exterior wall. Darkness keeps them dormant; warmth above 55°F triggers premature pale sprouts, and anything near freezing kills them. The same steady-cool conditions that store root vegetables work perfectly — our guide to building a root cellar covers how to create exactly that environment.

Winter Checks and Spring Division

Look in on the stored rhizomes about once a month. Healthy canna rhizomes stay firm and heavy; trouble shows as soft, mushy, foul-smelling spots (rot) or a shriveled, lightweight, wrinkled feel (too dry). Remove any rotting rhizome immediately so it does not infect the rest of the box, cutting back to clean, firm tissue if only a tip is affected. If many are shriveling, lightly mist the packing medium or move to a more humid spot; if you find mold or condensation, add ventilation and swap in drier medium. Cannas are generally robust in storage, so most years a quick monthly glance is all it takes.

As spring approaches, the eyes — small pink or white growth buds along the rhizomes — will begin to swell. That is the moment to divide. Using a clean, sharp knife, cut the clumps into pieces, making sure each division carries at least one or two healthy eyes, ideally three or four for a fast, vigorous plant. A rhizome chunk with no eye will not sprout. You can pot the divisions indoors four to six weeks before your last frost to get a head start on blooms, keeping them warm and lightly watered, then move them into the garden only after all danger of frost has passed and the soil has warmed — cannas have no frost tolerance once they break dormancy.

The Bottom Line

Overwintering cannas comes down to one question: does your ground freeze? In zone 8 and warmer, cut them back and bury them under a thick mulch. In zone 7 and colder, lift the rhizomes after frost, dry them for a few days, and store them cool, dark, and barely damp at 45 to 55°F, checking monthly and dividing in spring so every piece keeps its eyes. Either way you carry these tropical bloomers through the cold and multiply your stock for free — one clump becomes a stand of fiery foliage and flowers the following summer. To overwinter the rest of your tender bloomers like dahlias and gladiolus, browse our full library of plants and flowers guides.