Dahlias are gorgeous, but let’s be real: they aren’t exactly fans of the cold. Since they aren’t naturally winter-hardy, they usually need to be tucked away in a cozy indoor spot to survive the freezing months. However, in some specific cases, you can actually get away with overwintering them right in the ground.
Outdoor Overwintering: The Exception, Not the Rule
Generally speaking, your best bet is to move your dahlias somewhere frost-free. I usually recommend storing them in the cellar or keeping them in pots indoors. Leaving them outside is a bit of a gamble and should really only be tried as an exception.
What You Need for Outdoor Success
If you want to give outdoor overwintering a shot, there are a few boxes you need to tick to increase your chances:
- This works best in regions with mild winters where hard freezes are rare.
- You have to go the extra mile with frost protection to keep those tubers safe.
How to Overwinter Dahlias Outdoors
If you’ve decided to leave your tubers in the garden, here’s your game plan:
- Just like any other storage method, start by cutting the plants back completely. Leave just a small stalk—about four inches—poking out of the ground.
- Give the dahlia a “winter coat” by mounding a thick layer of soil and fallen leaves over it. For an extra layer of defense, you can even wrap the area with bubble wrap.
Extra Protection Tips
Beyond just leaves and soil, there are some great garden supplies you can use to keep the chill away:
- Burlap sacks
- Coconut fiber mats
- Winter garden fleece
These natural materials are fantastic for insulating the plant against the cold. Pro tip: Don’t be afraid to layer them! The more protection you provide, the better the odds that your dahlias will wake up happy in the spring.
The Risks of Leaving Them Outside
I have to be honest with you—there are some risks involved here. You never truly know how harsh a winter will be until it’s already here. If you do leave them out, try to make sure they are in a sheltered spot rather than an open, wind-swept area. Also, keep an eye on the moisture; if it’s a particularly wet winter, the tubers can easily rot because all that protective mulch can trap too much dampness.
Watch Out for Voles!
One last thing to keep in mind: hungry voles. These little garden critters love to snack on dahlia roots during the winter. If they get to your tubers, your plants won’t be able to send up any new shoots come springtime.
