Dahlias are not winter-hardy in our climate so they must be lifted for repeated use. The success of this process involves careful digging, curing, and storage to prevent the fleshy tubers from freezing or rotting.
After the first frost, the dahlia foliage will turn black and wilt, indicating the plant has entered dormancy. The following steps should then be taken:

— Cut off top vegetation leaving 4-6 inches of stem.

— Within one week, use a garden fork or spade to loosen soil in a wide circle around the plant, at least a foot away from the center. Gently pry entire clump out of the ground, taking care not to break the tubers.

— Label each clump with its variety name using a permanent marker on a tag.

Once dug, your tubers require preparation to prevent rot and shriveling.

— Gently remove excess soil from the clumps either with a gentle rinse with a garden hose or by gently brushing off the dirt.

— Allow tubers to air-dry in a cool, dry, and protected location for 1-2 days. This cures skins and allows any surface moisture to evaporate. Do not leave them in direct sunlight or on a concrete surface, which can dry them out too quickly.

— Examine each tuber clump for signs of rot, damage, or disease and discard any tubers that feel mushy or have dark, discolored flesh.

— Divide the clumps into individual tubers. Each individual tuber must have a visible “eye,” or a small piece of the stem with a bud, to sprout a new plant in the spring.

Maintain the right balance of moisture and air circulation to keep the tubers dormant and healthy throughout winter.

— Choose a storage medium that helps regulate moisture but avoids sogginess. Options include peat moss, vermiculite, wood shavings, or shredded newspaper.

— Place a layer of your storage medium in the bottom of a ventilated container such as a cardboard box, mesh bag, or plastic storage bin.

— Arrange the tubers in a single layer, ensuring they don’t touch, and cover with more medium. Repeat the layers until the container is full.

— Store tubers in a cool, dark, and dry location at 40°- 50°F. Unheated basements, attached garages, or root cellars often work well. Temperatures below freezing will kill the tubers.

— Inspect stored tubers monthly. If shriveled, lightly mist the storage medium with water to rehydrate them. Remove any tubers with mold or rot.

By following these steps, you can successfully preserve your beloved dahlia tubers, ensuring a spectacular show of blooms in your garden next season.

Submit gardening questions via ask.extension.org or call 719-520-7684. The in-person help desk is closed for the season. Questions submitted via Ask Extension will be answered remotely and phone messages will be answered biweekly.