To propagate dahlias by division, follow these steps. In the fall, carefully prune the dahlia back until it’s a stump, then gently dig away the topsoil until you can see the tuber and root system.

With the growing season slowing winding down for most, it’s just the opposite for Alyssa McDermott and her Newbury micro-farm. At Hay Street Flower Farm, McDermott is elbow-deep in earth, as it is ...