Dahlias originally hail from the sunny, warm landscapes of Mexico. Because of those tropical roots, they aren’t naturally built to handle our chilly winters. If you want to see those stunning blooms again next year, giving your dahlias a cozy place to stay for the winter is a must.
Are There Any Cold-Hardy Dahlias?
Unlike many other perennials in your garden, there really aren’t any truly “winter-hardy” dahlia varieties available for home gardeners. While there is a specific wild species in Mexico that can handle sub-zero temperatures, you won’t find that variety in your local garden center. The beautiful dahlias we all know and love—the ones bred in greenhouses and sunny backyard plots—simply can’t survive a deep freeze on their own.
Most dahlias can handle a very brief, light first frost without much trouble. In fact, that first nip of cold is often the signal to start moving them into their winter quarters to prevent the tubers from freezing solid.
The Best Way to Overwinter Your Dahlias
To make sure your dahlias come back with a bang next summer, you need to overwinter them correctly. Depending on your setup, you have a few options:
- Storing them in a basement or cellar
- Overwintering without a basement (like a frost-free garage)
- Keeping them in pots
- Trying your luck in the garden
Since they aren’t hardy, the gold standard is storing the tubers in a basement or another frost-free spot. The main goal is to keep those tubers tucked away where the frost can’t reach them all winter long.
Very few dahlias survive being left in the garden over the winter. If you’re feeling adventurous, you should only try this if you live in a very mild region with minimal frost. Even then, since no dahlia is truly winter-proof, you’ll need to provide some serious extra protection.
Protecting Them from the Cold
If you decide to leave your dahlias in the ground, extra insulation is non-negotiable. You’ll want to cover the area with a thick layer of mulch—think fallen leaves, straw, or evergreen branches. When it comes to insulation, more is definitely better! Adding a few inches of soil on top of your mulch layer can also help seal in the warmth.
You can also use specialized garden gear for an extra layer of defense:
- Thermal garden fleece
- Burlap sacks
- Coconut fiber mats
These natural fiber products add a great buffer against the biting cold. Feel free to stack these methods, too—the more protection you give your dahlias, the better their chances of sprouting back to life once spring rolls around.
Spring Tips for Your Dahlias
Don’t be in too much of a hurry to plant your dahlias back outside! Wait until the danger of the last spring frost has passed (usually after Mother’s Day in many regions). If a surprise frost is forecasted after you’ve planted them, be ready to move your pots indoors overnight or cover your garden beds with fleece or burlap to keep those tender new shoots safe.
