Worried about your dahlias surviving the winter chill?
If you’re passionate about these stunning blooms, you know they need a little extra care to make it through the colder months.
Don’t let frost steal their beauty.
Follow these simple steps to winterize your dahlias and ensure they return even more vibrant next spring.
How To Correctly Store Your Dahlias Over Winter
Why Overwintering Dahlias is Essential
Dahlias are not just another pretty flower; they are tropical beauties that thrive in warm weather.
Unfortunately, this means they are not frost-tolerant.
When the temperature drops, dahlia tubers, those precious root systems, can easily rot or be damaged by freezing.
By properly winterizing your dahlias, you’re safeguarding next year’s blooms and ensuring all your hard gardening work doesn’t go to waste.
Step-by-Step Guide to Winterizing Dahlias
1. Timing is Key
Start the winterizing process after the first hard frost, which will kill the top growth. Dahlias need this time to allow their tubers to mature, which improves their chances of surviving in storage. Keep an eye on your local weather forecast to act at the right time, typically in late fall.
2. Cutting Back
Wait to cut back the stems until just before digging up the tubers. This prevents water from collecting in the hollow stems, which can lead to crown rot and tuber decay.
Once ready, use clean garden shears to trim the stems down to about 4–6 inches above the ground.
3. Digging Up Tubers
Approximately two weeks after the first frost, when the foliage has died back, carefully dig up the tubers.
Use a garden fork or spade to loosen the soil around the entire plant, starting at least a foot away from the stem to avoid damaging the delicate tuber necks.
Gently lift the tubers from the ground, being careful not to cut or skin them, as any damage can lead to rot and disease during storage.
4. Cleaning and Drying
Once dug up, remove and discard the mother tuber as it wont produce new growth and may rot in storage. Also get rid of any remaining soil from the tubers.
Rinse them with water if necessary, but be sure to let them dry completely. Consider hanging them upside down for a couple of weeks to help cure them, which helps prevent rot during storage.
5. Dividing The Tubers (Optional)
To expand your dahlia collection, you can divide the tubers before storage. Locate the “eyes” which are small growth points near the crown where the tuber connects to the stem.
Using a clean knife, carefully cut the clump into individual tubers, ensuring each piece has at least one eye.
Discard the original mother tuber, as it won’t produce new growth and may rot. Allow the cut tubers to dry for a day or two in a cool, dry place before storing them.
6. Storing Tubers
Store the dried tubers in a box lined with peat moss, sawdust, or vermiculite. Some gardeners even use newspaper. The key is to keep them in a cool (40-50°F), dry, and dark place. Make sure the tubers are not touching each other to avoid the spread of any potential rot.
Some gardeners recommend keeping slightly moist peat moss to reduce the chance of the tubers completely drying out inside or shriveling.
You can optionally sprinkle sulfur dust on them or another fungicide to reduce the chance of disease during storage.
7. Labeling for Next Season
Before you tuck them away for the winter, label your tubers with the dahlia variety. This small step will save you a lot of guesswork when it’s time to plant them again in spring.
Common Mistakes to Avoid
Storing in a Damp Environment: Moisture is the enemy here. Even a little dampness can cause tubers to rot, so make sure they are completely dry and stored in a dry area.
Forgetting to Check: Set a reminder to check your stored tubers once a month. If any show signs of rot, remove them immediately to protect the healthy ones.
Not Labeling Tubers: Without labels, you might mix up your dahlias next season. Take the time to tag each one, and you’ll thank yourself later.
Bonus Tips for Success
Inspect Tubers During Storage: It’s a good idea to check on your tubers periodically throughout the winter. Look for any signs of rot or shriveling and address issues as soon as you spot them.
Prepare for Spring Early: When winter ends, start thinking about where you’ll replant your dahlias. They’ll need a sunny spot with well-drained soil to thrive once the risk of frost is gone.
Label Before First Frost: This makes identification much easier as you can still recognize the foliage.
With just a bit of effort now, your dahlias will be well-prepared to burst back to life when spring arrives.
These steps might seem simple, but they’re crucial to ensuring your dahlias don’t just survive the winter, they thrive in the seasons to come.
FAQs
In very mild climates (USDA hardiness zones 9-11), dahlias can sometimes be left in the ground with heavy mulch. In zone 8, the ground may still freeze enough to damage the tubers, so it’s safer to dig them up. Digging them up is the most reliable way to protect them from frost.
Using a garage, basement, or even a closet is a good idea. The key is to keep them dry and at a steady, cool temperature—ideally above freezing but below 50°F (10°C).
Wait until all danger of frost has passed. Dahlias love warm soil, so plant them once soil temperatures are consistently above 60°F (16°C).
Want More?
Now that you have winterizing dahlias mastered, why not learn how to overwinter ferns, hostas or hydrangeas?
All of these tasks are part of many gardeners winter garden prep, to ready them for spring.