Hi Deb, I'm in zone 4/5 too, and I overwinter my flats in an unheated garage. Plants that are established in larger pots than flats do OK outside, even without much snow cover. The ones in the ground do well too. But flats offer much less protection to the roots so I prefer to keep them in the garage. (It's not uncommon to have temps below zero here in winter.) About once every other month I give them just a small bit of (cold) water, maybe a tablespoon per plant. Mine are on a table in the garage where they get minimal light through the windows. They do go dormant, often closing up into tight little balls that look nothing like they did when winter began. That's OK, in spring they quickly return to their beautiful selves. As brutal as our winters are, they'd much rather be outside than in the house.
