Lawn & Garden • Iowa Fall Garden • Updated October 30, 2026

How to Store Dahlias and Cannas Over Winter in Iowa

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Dahlias and cannas bloom right up to the first hard frost, but they cannot survive an Iowa winter in the ground. The good news: their tubers and rhizomes are easy to save. Dig them a few days after a killing frost, let them dry, and store them somewhere cool and dry until spring. This guide walks through how to store dahlias and cannas over winter, step by step, based on Iowa State University Extension and Outreach guidance.

The short answer

A few days after a hard, killing frost, cut dahlias back to 2 to 4 inches and cannas to 4 to 6 inches. Dig the clumps carefully, let dahlias dry for about a day and cannas for 1 to 2 days, then store them in a cool (40 to 50°F), dry place. Dahlias go upside down in boxes covered with vermiculite, peat moss or wood shavings; cannas go in boxes, crates or mesh bags. That is the Iowa State University Extension method.

When to dig dahlias and cannas in Iowa

Wait for the first hard, killing frost that blackens the leaves. In much of Iowa that usually happens in October, a little earlier in the north and later in the south. The frost signals the plants to stop growing, and the few days after it give the tubers a chance to firm up.

Don’t wait too long, though. Dig before the ground freezes hard, and pick a dry day: wet, muddy clumps are harder to clean and slower to dry.

How to store dahlias over winter

1. Cut back. Within a few days of a killing frost, cut stems to within 2 to 4 inches of the ground.
2. Dig carefully. Use a spade or digging fork and start a foot or so from the stem so you don’t slice into the tubers. Lift the whole clump.
3. Clean. Shake off the soil, cut the stems back to the crown and wash off the remaining soil.
4. Dry. Let the clumps dry until they are dry to the touch, usually about one day.
5. Label. Mark each clump with its variety or color before they all look the same.
6. Pack. Place the clumps upside down in boxes or containers and cover them with vermiculite, peat moss or wood shavings.
7. Store cool and dry. Keep them at 40 to 50°F, for example in a cool basement, root cellar or attached garage that does not freeze.

A fork lifts a clump with less risk of slicing tubers than a sharp spade. This border fork is a manageable size for flower beds.

How to store cannas over winter

1. Cut back. A few days after a hard, killing frost, cut cannas to 4 to 6 inches above the ground.
2. Dig. Lift the clumps with a spade or fork, leaving a small amount of soil on the rhizomes.
3. Dry. Let them dry for 1 to 2 days in a frost-free spot.
4. Pack. Place the clumps in large boxes, wire crates or mesh bags.
5. Store cool and dry. Keep them at 40 to 50°F in a dry location.

Thick canna and dahlia stalks are tough for small snips. Geared bypass pruners cut stems up to 3/4 inch with less hand effort.

Dahlias vs cannas: side-by-side

Gladiolus are different. ISU Extension says to dig them in late summer or early fall, cut the foliage to 1 to 2 inches above the corms, dry them for 2 to 3 weeks in a warm, airy place, and store them at 35 to 45°F in mesh bags or old nylon stockings.

Check them during winter

Stored tubers are alive, so look at them every few weeks. Remove any that are soft or rotting so the problem doesn’t spread. If they are badly shriveled, the storage area is too dry: lightly moisten the packing material, but don’t soak it, because too much moisture causes rot. A min/max thermometer shows whether the storage spot stays in the 40 to 50°F range, including on the coldest nights.

Replanting in spring

In spring, divide large clumps before planting. ISU Extension advises leaving at least one or two dormant buds (eyes) on each section. Plant dahlias and cannas outdoors after the danger of frost has passed and the soil has warmed; see our Iowa last frost dates by city.

Supplies for storing dahlias and cannas

The fork and pruners above cover digging and cutting back. These three items handle storage. All were listed as sold by Amazon.com when checked on October 30, 2026.

Packing material: Kaytee Pine Bedding

ISU lists wood shavings as a dahlia storage medium. A bag of plain pine bedding is an easy, low-dust source. Use it dry, and cover the tubers completely.

Labels: waterproof plant tags

Once dug, every dahlia clump looks the same. Label each one with its variety or color before you pack them, using a pencil or garden marker.

Monitor the storage spot: Taylor min/max thermometer

Sold as a fridge and freezer thermometer, its min/max memory also works in a basement or garage: it shows how cold the spot gets overnight, so you know the tubers stay above freezing and near 40 to 50°F.

FAQs

When should I dig up dahlias in Iowa?
A few days after a hard, killing frost blackens the leaves, which usually happens in October in much of Iowa. Cut the stems to 2 to 4 inches first, then dig before the ground freezes.

Can dahlias and cannas stay in the ground over winter in Iowa?
No. Iowa State University Extension says tender perennials such as dahlias and cannas will not survive Iowa winters outdoors and must be dug in fall and stored indoors.

What temperature should dahlias and cannas be stored at?
Cool and dry, at 40 to 50°F, according to ISU Extension. A basement, root cellar or attached garage that does not freeze often works.

What do you pack dahlia tubers in for winter?
ISU Extension recommends placing clumps upside down in boxes and covering them with vermiculite, peat moss or wood shavings.

Do I wash canna rhizomes before storing them?
No. ISU Extension suggests leaving a small amount of soil on canna clumps, letting them dry 1 to 2 days, and storing them in boxes, crates or mesh bags.

Sources

• Iowa State University Extension and Outreach – How to Overwinter Tender Perennials
• ISU Extension – How do I over-winter dahlias?
• ISU Extension – Yard and Garden: Over-wintering Tender Perennials

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