Digging and Storing Dahlia Tubers
This is the time of year to harvest dahlia tubers, before or after the first hard frost. If your plan is to dig the tubers early you need to cut the stalks down to 8-10” above the ground. This prompts the formation of nodes on the tubers. If you allow your dahlias to experience a hard frost the stalks will dieback naturally.
Use a garden fork to loosen the soil around the tuber. Carefully lift the tuber out of the soil and wash gently to remove remaining dirt. Allow the tuber to dry for 24 hours in a cool, dry location.
This is a good time to divide large dahlia tubers into smaller sections. Each new division must have an eye (bud) to produce a new plant. Use a sharp, clean knife to divide tubers into sections.
Place tubers in a cardboard box with sawdust, dry peat moss or vermiculite. Label the storage container to help you identify the tubers next year. Be sure to dust the tubers with Green Earth garden sulphur powder to prevent rot and disease while in storage (it is harmless to pets and children).
Choose a storage location in a dry area where the temperature will remain near 10 degrees C or 48 F. Check on the tubers periodically during the winter. Look for signs of shriveling. If the tubers are beginning to shrivel I recommend that you moisten the storage medium to ‘beef’ them up again. But be sure to check weekly for mildew or rot.