How to Store Dahlia Tubers Over Winter

Dahlias are my favorite thing in the cut flower garden. If you want them back next year, giving them the care that they need this fall season goes a long way. Whether you leave your tubers in the ground or dig them up, I’ll share tips on overwintering, dividing, and storing dahlia tubers so they’re ready to bloom again come summer.

This post covers how to know the best method for your area, how to safely dig and split your dahlias, and three ways to store tubers indoors.

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Choosing How to Store Dahlia Tubers Over Winter

Your climate dictates whether you can leave your dahlia tubers in the ground or lift and store them somewhere safe until the danger of freezing has passed.

Storing Dahlia Tubers in Mild Winters

Because I’m in a milder climate (Zone 8b), I’ve been lucky. In the ten years I’ve grown dahlias, I’ve only dug and stored the tubers once.

If you leave yours in the ground, protect them from freezing through the coldest months with about a 3-inch layer of organic leaf mulch around each plant.

One honest caveat: in a wetter-than-usual winter, I’ve lost around 15% of in-ground tubers to rot. But I actually had more rot the one year I stored them out of the ground, so in-ground isn’t necessarily the riskier choice here.

Storing Dahlia Tubers in Colder Climates

In most regions, winters are too cold to leave tubers in the ground. There, cut the plants back at the end of the season, once the top growth dies back or turns black by the first frost. With clean, sharp pruners or loppers, cut all but about 4 inches of the top growth.

The longer tubers stay in the ground, the more they mature, which improves their odds in storage, but you want them out before the first hard freeze. You can look up your average first and last frost dates here.

How to Safely Dig Up and Split Dahlia Tubers

Whether you store your dahlias or leave them in the ground, you’ll still need to dig them up at some point to split and inspect them. For the full walkthrough, see my post on splitting dahlia tubers in the spring. Here’s how I dig and store mine.

Label Your Dahlia Tubers

Label your dahlias before the blooms fade so you can keep track of each variety once they’re out of the ground. Even if you leave them in the ground, you’ll want the labels to find each plant next year when it’s time to dig and divide the tubers.

Dig Up Your Dahlia Tubers

Whichever overwintering method you choose, the digging process is the same:

1. Use a shovel or garden fork to dig around the clumps, taking care not to slice through the tubers. I use a pitchfork, since the tubers are so easy to damage.
2. Gently shake the excess dirt off the tubers and set them aside.
3. Repeat until you’ve lifted all your clumps.

Split Your Dahlia Tubers

You can divide your dahlia clumps at any of these points:

I dig mine up in April to split and inspect them, toss anything rotted or diseased, and remove the old mother tuber. After splitting, I plant them right back in their holes and wait for summer blooms.

How to Store Dahlia Tubers Over Winter Indoors

If you’re lifting your tubers to avoid risk of frost, here are three methods I’ve used or seen work well.

Method 1: Paper Bags or Cardboard Boxes

This is the method I’ve used myself.

Rinse and Examine the Tubers

Rinse the clumps to remove excess soil, then dip them in a 5% bleach, 95% water solution. Once rinsed, check each clump for damage or rot.

Divide If the Eyes are Visible

If you can see several growth eyes, you can divide now. Use a sharp knife or pruners, making sure each piece keeps at least one eye. The eyes are the cells that produce next season’s plants and blooms. I have much better luck spotting them in spring, so if you can’t find them in fall, wait and divide in early spring when they’re easier to see.

Make Sure They’re Fully Dry

To prevent rot, let the tubers dry completely before storing. Some gardeners dry them for weeks; others just a couple of days. Ours dry quickly, thanks to the wood-burning stove in our outbuilding. Once dry, store them somewhere dark, cool, and freeze-free, ideally 40 to 50°F: an unheated basement, closet, utility room, or attic.

Pack Them Properly

Nestle the tubers in slightly dampened peat moss, sawdust, wood shavings, or coarse vermiculite, then set them in a cardboard box or paper bag lined with newspaper. They need good airflow, so keep them from touching and give them room to breathe. I check mine for rot once a month all winter.

Method 2: Deep Bulb Crates

After digging, shake off the excess dirt, set the whole clumps into deep bulb crates, and stack them into a 40 to 50°F basement or garage. The clinging soil seems to keep the tubers hydrated enough that they don’t shrivel. In mid to late March, pull the crates out, rinse the clumps, and start dividing.

Method 3: Plastic Wrap

This is the Saran Wrap method. Rinse the clumps to remove soil, dip them into a 5% bleach, 95% water solution, and check each one for damage or rot. Lay them out to dry in a cool garage or basement for a day or two. Once dry, carefully divide the clumps and wrap each tuber separately in plastic wrap.

Place the wrapped tubers in plastic bulb crates and store at 40 to 50° F through winter.

I have mixed feelings about this method:

• Pro: The wrap keeps each tuber separate, so if one rots, the rest stays safe.
• Con: Wrapping each tuber individually is time-consuming.

Common Questions About Storing Dahlia Tubers Over Winter

Final Thoughts on Storing Dahlia Tubers

With a few simple steps, you can bring these beautiful blooms back year after year. Wait for the first frost, dig gently, let the tubers dry, and tuck them somewhere cool and dark while they’re dormant. For more on growing and dividing, see my Dahlia Planting Guide for Beginners.

If you have questions or a method of your own to share, leave it in the comments, and pass this along to a fellow gardener who could use it.

Until next time.

Happy Gardening!

I’m a self-taught hobby gardener. Everything I share on my blog is my opinion and what has worked for me.

For tips on saving plants over the winter, visit my friend Rachel of The Ponds Farmhouse, where she uses her gorgeous greenhouse to overwinter her plants.