When and How to Dig Dahlia Tubers in Fall: A Step-by-Step Guide
When and How to Dig Dahlia Tubers in Fall: A Step-by-Step Guide
Fall arrives. The first frost hits. And suddenly those magnificent plants that filled your garden all summer are black and drooping — and underneath them is next year's garden waiting to be saved.
Digging dahlia tubers is one of the most satisfying moments of the growing season. It's also one of the most nerve-wracking if you've never done it before. Here's exactly how we do it at Rooted Dahlias, every fall, across thousands of plants.
When to Dig Dahlia Tubers
The timing of digging matters more than most growers realize.
Wait for a killing frost. A light frost that nips the tips is not your signal to dig. Wait for a hard frost — temperatures below 28°F for several hours — that kills the foliage completely. The tops will turn black and collapse. That's your signal.
Why wait? Right up until that killing frost, your dahlia plant is still sending energy down into the tubers. The longer you leave them in the ground after the season ends, the more developed and viable those tubers become for next year. Digging too early costs you tuber quality.
Don't wait too long. Once a killing frost hits, watch overnight temperatures. If the ground freezes solid the tubers become impossible to extract without damage — and frozen tubers are lost tubers.
In most of the US, digging season runs from mid-October through November depending on your zone.
What You Need
- Garden fork
- Sharp pruners or loppers
- Labels and a marker
- Somewhere dry and sheltered to lay clumps for curing
How to Dig Dahlia Tubers: Step by Step
Step 1 — Cut the stalks
Cut each stalk down to 4–6 inches above the ground. This gives you a handle to work with and reduces the weight and leverage that can snap tuber necks during digging.
Step 2 — Mark your varieties
Label each stalk with the variety name before you dig. Once tubers are out of the ground they all look remarkably similar — and a clump of unlabeled tubers is a clump of mystery dahlias. We use metal plant stakes with the variety name written in permanent marker.
Step 3 — Work your fork in wide circles
Push your garden fork into the soil about 12 inches away from the stalk and work it in a wide circle around the plant, going down 10–12 inches. You're loosening the soil around the clump, not prying it up yet.
Step 4 — Lever up from below
Once the soil is loosened on all sides, push your fork under the clump and lever it upward from below. Do not pull from the stalk — the neck connecting the stalk to the tubers is the most fragile point and it breaks easily. Work from below and let the fork do the lifting.
Step 5 — Lift and inspect
Lift the clump free and gently shake off loose soil. Inspect for any tubers that were cut or speared by the fork — these won't store well and should be set aside.
Step 6 — Rinse or leave dirty?
This is a matter of preference and climate. In wet climates, rinsing clumps with a hose removes soil that can harbor rot organisms. In dry climates, leaving soil on is fine and can even protect tubers during curing. We rinse our clumps to remove soil and prepare them for shipping to your garden in the spring.
After Digging: Curing Your Tubers
Lay clumps upside down — stalks pointing down — in a cool, sheltered spot with good airflow for up to a week. A barn, garage, or covered porch works perfectly. Tubers should be dry to the touch, but not allowed to begin shriveling or drying out. This curing period allows:
- Residual moisture in the stalks to drain away from the tubers
- The skin to firm and toughen against rot
- Any small cuts or wounds to callous over
Don't skip curing. It's the step between a successful dig and a successful storage.
Dividing Your Clumps
You can divide now or in spring — we prefer fall when the eyes are most visible and easier to identify. If you divide in fall, use sharp, clean snips and make sure each division has at least one healthy eye — the small growth node where the tuber meets the neck. A tuber without an eye will never sprout.
Storage
Once cured, store tubers in a cool dark space between 35–50°F in peat moss, vermiculite, or slightly damp sawdust. Check frequently and remove any tubers showing rot immediately. For a complete storage guide, read our full post on how to store dahlia tubers over winter.
One Last Thing
Every tuber you dig this fall started as something we grew at Rooted Dahlias — or could next season. Our shop opens every December with hand-dug tubers from our farm, shipped to your door in time for spring planting.
If this fall's garden has you dreaming about next year's blooms, join our waitlist at rooteddahlias.com/pages/waitlist. You'll get early access before the shop opens — and first pick of the varieties that sell out fastest. 🌸
Rooted here. Blooming there.