By Keith Wilson
Fall & Winter Care For Dahlia’s
Dahlias provide us with long-lasting beauty from mid-summer through fall. The dahlia tubers require proper storage for these summer “workhorses” to endure over the years. Here are two different options I use to preserve these productive and versatile cut flowers.
If you are going to dig up your tubers, wait for two weeks after the first hard frost or until mid-November, whichever happens first. Cut the stems at the ground level. Carefully dig the clump of tubers to avoid cutting or breaking them. Gently shake and remove excess soil.
The tubers do not need to be washed, just freed of wet clumps of soil. Place them in a dry location for four days to harden up and dry out on the exterior surface.
Store in a cool basement or garage (45 to 50 degrees, ensure it’s in a location that doesn’t freeze.)
Make sure clumps are labeled with their appropriate names. Cover them with vermiculite or somewhat dry peat moss.
These can be divided in the spring. I recommend planting them around Mother’s Day. Buds (eyes) will form on the stored tubers in the spring. Divide them as desired. Allow the cut tissue to air-dry for a few days to form a callus before planting.
Leave in the Ground Method
Alternatively, dahlia tubers may be left in the ground for the winter in our Puget Sound area (Plant Hardiness Zone 8b). Wait two weeks after the first hard frost or until mid-November, then cut them to ground level. Cover the cut stubs and tubers with thick plastic sheeting. This protects them from the cold winter rains that can rot the plant.
Mulch with leaves, soil, or compost. Cover with two to three inches of mulch on top of the plastic for insulation in case of an extended freezing spell. Remove this protection in mid-April. Many varieties sprout above the soil surface in late April.