Grow guide

Digging and storing dahlia tubers

Dahlias aren't winter-hardy in Massachusetts: tubers left in the ground freeze and rot. Digging them each fall and storing them indoors is how you keep, and multiply, your favourite varieties from year to year.

When to dig

Wait for the first frost to blacken the foliage, usually October in most of Massachusetts. Dig before the ground freezes hard.

Digging up the clump

Cut the stems down to about 6 inches, and label each plant with its variety.
Loosen the soil in a wide circle around the plant with a fork, well out from the stem, so you don't spear the tubers.
Lift the whole clump gently. The tuber necks are fragile, and a tuber with a broken neck won't sprout.
Rinse or shake off the soil.

Dividing

You can divide in fall or in spring. Each division needs a piece of the old stem's crown with at least one eye, the small bud that sprouts next year. A tuber with no eye won't grow, however plump it is. Many growers find eyes easier to see in spring, so they store the clumps whole and divide just before planting.

Drying and storing

Let the tubers air-dry for a day or so, out of the sun and frost, until the surface is dry.
Pack them in a box or bin with slightly damp wood shavings, peat or vermiculite, or wrap them individually in plastic wrap.
Store them somewhere cool that doesn't freeze, about 40–50 °F. A basement, cool garage or crawl space often works.
Aim for moderate humidity, around 50–60%: too dry and the tubers shrivel, too damp and they rot. Check them once a month. Our printable storage log keeps track. Remove any that are rotting, and mist the packing lightly if tubers start to shrivel.

Spring: plant after the last frost, usually late May here. Starting tubers in pots indoors a few weeks earlier gets you flowers sooner.

Dahlias from Groton

We grow dahlias in Groton, Massachusetts, for spring tubers and for cut stems from late summer until frost. See our dahlia varieties and reserve tubers for spring.

Reserve dahlias

Sources: UMass Amherst Extension, Hort Notes 2024 vol. 35:8 (digging, drying, humidity, storage) and Hort Notes 2026 vol. 37:8 (40–50 °F storage).

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