Certified GKH Gardening Expert
Tender bulbs, such as dahlia, actually require lifting each fall and overwintering indoors in cold regions like yours. Only in warm, southern regions can these bulbs be left in the ground year round. They can be easily lifted with a garden fork or spade shovel prior to the complete die out of their foliage. Break up the clumps and separate the bulbs, allowing them to dry out some before storing, usually about a week or two in a cool, dry area. Then, clip off the foliage, shake off any remaining soil and pack the bulbs in dry peat moss or wood shavings within a brown paper bag or cardboard box. Place them in a dark area with cool room temperatures, like a basement, until spring.