Simply said, "our dahlias are weaklings." They need special care. These glorious and prolific bloomers don't like our soggy winters. The endless rain and freeze/thaw cycles will rot the tender tubers.
If you want these Primadonna flowers to survive the winter, there are a few steps to their care. First, you can dig them up, wash them off, wrap in newspaper, then store in a cool garage or basement. In the spring, after the danger of frost has past, you can replant the tuber clump. Otherwise, if you leave them in the ground, follow the next steps in the photos. In late March or April, uncover the rows and get your slug bait out to allow the new shoots to grow.
1. Wait until the first frost or after November 15th. Cut the stems to the ground.
2. Cover rows with black plastic strips. This will keep them mostly dry for the winter.
3. Lastly, cover the rows with thick layer of straw to act as a winter blanket.