November 5, 2025, 4:48 am | Read time: 3 minutes
When the last dahlias have faded in the fall and the nights grow cooler, it’s time to think about winter. myHOMEBOOK gardening expert Franka Kruse-Gering explains what to consider when you want to overwinter dahlias.
Dahlias originate from Mexico and are not adapted to frost. Their underground tubers store nutrients and water, but they are very sensitive to cold. Just a few degrees below freezing can destroy them. To ensure the plants sprout and bloom again next year, the tubers must be dug up in the fall and stored in a frost-free place. With some preparation and a suitable storage location, this can be done without any problems.
Don’t Miss the Right Time
As soon as the first light frost blackens the leaves, the dormancy phase begins. Now is the ideal time to dig up the tubers. Digging too early is not beneficial because the plant only fully stores its nutrients in the tuber after blooming. Waiting too long, however, risks frost damage.
First, cut the stems about a hand’s width above the ground. Then carefully lift the tubers with a digging fork or a small shovel, taking care not to damage them. Remove any clinging soil roughly, but leave the fine roots attached.
How to Prepare Dahlias for Overwintering
Before the tubers move to their winter quarters, they need time to dry. It’s best to lay them out for a few days in a well-ventilated, frost-free place—such as a garage or shed. Moisture can easily lead to rot, so the soil should dry out a bit. Once clean enough, larger soil residues can be removed.
Tip: If desired, label each variety to avoid confusion in the spring. This is especially helpful with multiple colors or flower forms.
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The Perfect Place for Overwintering
Dahlias prefer a cool, dark, and dry environment in winter. The temperature should be between 39 and 46 degrees Fahrenheit. Suitable locations include basements, frost-free garages, or garden sheds. Good air circulation prevents mold.
Also interesting: Planting and Care Tips for Dahlias
The tubers are loosely placed in wooden boxes, cardboard boxes, or baskets. Dry leaves, sawdust, or some sand can be used as a layer between them to prevent contact. It’s important they don’t dry out, but also don’t accumulate moisture. Regular checks are worthwhile—rotting tubers should be removed immediately.
Starting the New Gardening Season
From March, the tubers can be brought back into the light. If desired, place them in shallow boxes with some soil and lightly moisten them. This encourages earlier sprouting. After the Ice Saints, when there’s no longer a risk of frost, they can be moved outdoors again. A sunny location and nutrient-rich soil ensure a strong start to the new season.