Dahlias do not tolerate frosty temperatures and therefore cannot be overwintered outdoors. How they bloom beautifully again next year, you will learn in our guide.
Formerly often called Georgine, the beautiful dahlia originates from North American Mexico. The garden dahlias used in this country are usually crosses of two specific wild species. Since the plant is extremely sensitive to frost, it does not survive the winter outdoors in Europe.
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Overwintering dahlias:
Compared to many other frost-sensitive plants, dahlias are brought inside only after the first light frost nights. Once the upper flower parts have died from the frost and the leaves have wilted, you’re good to go:
Cut off the plant parts about five to ten inches above the ground.
Then start digging up the roots of the dahlias. The best time to remove the large tubers is when the soil is thoroughly dry. You should never take them out of the bed too early, otherwise they will not store enough nutrients for the coming year.
Let the roots dry for a few days. Then sort out rotten and pest-infested tubers and remove the last coarse soil residues.
Tip: Slightly injured tubers do not have to be thrown away. Simply cut out the damaged area with a sharp knife and then sprinkle a little charcoal powder on the open areas.
The optimal winter quarters for dahlias
Dahlia tubers are not demanding in the winter. If their winter quarters meet the following requirements, they usually survive the cold months very well:
Line a few old wooden boxes with newspaper and place the tubers inside. Cover them with sand at the end so they don’t dry out or rot.
Then store the filled boxes in a dark, dry cellar. The optimal temperature is 3 -8 degrees Celsius and should not fluctuate too much. Caution: If it is too warm in the winter quarters, the dahlias may sprout again too early.
Check the tubers every few weeks for rot and mold and sort out broken roots.
Dahlias do not require additional care during the winter months.
Planting dahlias in spring
Between the end of April and the beginning of May you can plant the tubers back into the bed. If the roots are very dry, simply soak them in water for a few hours before planting. Then plant them about five centimeters deep in the ground and cover them with soil.
Tip: With dahlias, you don’t necessarily have to wait for the last frosts in spring. As a rule, they are no longer damaged by this.