Many gardeners lost their precious dahlias in the Arctic storm in February last year. Dahlias are long-lived, tender perennials from their homeland Mexico, but can be damaged in frozen soil. Digging and storing dahlias before freezing will help keep them alive and healthy.
When the temperature drops to between 36 and 32°F, the best time to remove the dahlia is after a slight frost. The leaves and stems will be killed at 32°F, but the tubers will not be damaged. However, tubers can be damaged by continued hard freezing.
The average date for the first freezing in our planting area is around October 31, so please prepare the dahlia tubers as soon as possible so that they can be removed from the garden. The tubers are hardened after being lifted by deduction of water and a slight freezing in winter storage.
First cut the leaves back a few inches from the ground to dig out the tubers. Use lifting forks or flower shovel to dig around and below the base of the plant. The tuber can spread underground, so be careful to avoid damaging the tuber; digging too close to the stem may cut the tuber and cause a wound in which pathogens enter. Carefully dig completely around and under the tuber, lifting gently. When the whole tuber is free, shake off the soil. If the tubers have not split recently, expect a few clumps, one clump per root.
When the tuber block has no loose soil, rinse the tuber with a gentle stream of water. Avoid piercing the tender skin, otherwise it will promote rot during storage.
Tubers are swollen underground stems that can reproduce asexually from many eyes. Dahlia’s eyes are tiny protruding tissues from which the stems of the next season will grow. You can increase the number of tubers by cutting with a sharp, clean knife, leaving at least one eye.
After the tubers have completely dried for several weeks, treat them before storing them. Pickled tubers will minimize rot during storage. After the tubers are dry, cut off the remaining dahlia stems with clean pruning shears. Store in a place with no freezing, good ventilation and low light.
Tubers can be stored in cartons, milk crates, cardboard boxes, paper bags or plastic boxes. Regardless of the container used, leave space between each tuber to ensure adequate air circulation. The container can be stored in a garage or attic where it will not freeze, or in a house to keep it as cool as possible.
When the danger of freezing in spring has passed, dahlias can be replanted in gardens or courtyards. Dahlias grown in pots are amazing specimens; the conventional potting medium is modified with topsoil to provide a heavier mixture.
Ellen Peffley has taught gardening at the university for 28 years, including 25 years at Texas Tech University, during which time she developed two onion varieties. She is now the sole proprietor of From the Garden, a market garden farm.
Post time: Nov-03-2021