Tuber Dividing & Storage Tips

This is my approach for digging, dividing, and storing dahlias. Many other approaches work - you just have to find what works best for you!

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🍂 Labeling
As the season winds down, it’s time to start thinking ahead to next year. First step: label your plants while they’re still blooming and easy to identify.

Here’s how I do it:
✦ Use flagging tape (bright, weatherproof, easy to spot)
✦ Write the variety name with a Garden Mark pen (doesn’t fade in the elements)
✦ Tie the tape securely to the main stem at ground level

That way, when it’s time to dig and store tubers, you’ll know exactly who’s who—no mysteries in the spring!

 

🍂 Preparation

Dahlias need to stay in the ground at least 120 days from planting to allow their tubers to mature. A killing frost isn’t required before digging—but I prefer to wait for it, since the frost signals the season’s natural end.

Here’s what I do once frost hits:
✦ Cut the tops off, leaving about 12 inches of the main stem. This stem stub makes it easier to pull the clump out later.
✦ Leave the clumps in the ground for 5–7 days. This helps the tuber skins cure and toughen, improving storage.

After that, they’re ready to dig!

 

🍂 Digging & Washing

Now that you’ve let the clumps rest, it’s time to lift, clean, and bring them inside for dividing: 

• Carefully dig four sides around the clump, about 12" (30 cm) out from the main stalk, using a garden fork.

• On the last side, gently lever the clump up with the fork while supporting the clump by the main stalk — use the stalk as your handle.

• Remove large chunks of soil by hand (work gently so you don’t break tubers).

• Use the jet setting on a hose or sprayer to wash away remaining dirt and debris — blast enough to reveal where tubers connect but don’t gouge them.

• Bring the cleaned clumps inside and set them aside for dividing.

Reminder: Go slow and be gentle with the fork - the biggest damage to tubers is accidental stabbing or prying. Keep the variety label attached during the whole process so you don't lose IDs before dividing. 

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🍂 Dividing

I like to divide my dahlias right after they come out of the ground, while the tubers are still hydrated and easy to work with. That means I only dig as many clumps as I can divide in one session.

Here’s my process:

✦ Sharpen your tools and keep them sanitized between every clump to prevent disease spread.
✦ Keep the label with your work.
✦ Cut off the main stalk close to the crown.
✦ Trim away the fine “hairy” roots so only the firm tuber remains.
✦ Remove and discard any broken or damaged tubers.
✦ Remove and discard the “mother” tuber (the original tuber planted at the start of the season). It has already done its job and usually won’t produce again.
✦ Carefully separate the clump, making sure each tuber you keep has:
 • A piece of crown (the base of the stem where eyes form)
 • A visible eye (the growing point for next year)
 • A sturdy neck (so it won’t snap off)
 • A firm, healthy tuber body

Tubers without eyes, with damaged necks, or with soft spots can also be discarded.

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🍂 Storage

Once your tubers are divided and trimmed, it’s time to cure and store them for the winter.

Here’s what I do:
✦ Lay the tubers out on paper towels in a cool, dry, well-ventilated spot for 24–48 hours.
✦ They’re ready for the next step when you can write on them with a Sharpie without the ink smearing. I label each tuber individually with its variety name.
✦ After labeling, I wrap each tuber individually in plastic wrap and group them into packets of about five tubers.
✦ Place the packets into a plastic container lined with newspaper.
✦ Store the containers in a refrigerator set to 44–46°F. (An Inkbird controller keeps the fridge temperature consistent and slightly warmer than a typical fridge) ​