I live in Florida. We don't generally experience the season others term winter. A couple cold days. This past year was unusual in that we had several of those days in a row. Heat plate for the first weeks, as soon as we are over 40s overnight, if they are big enough to be out of the brooder, they are big enough to tolerate days unassistedDid you ever run into temperature issues with your chicks ranging in age? 7 week olds may not need a heat source but wouldn’t the 4 week olds? My 10 week olds are in the coop day and night but the 5 week old is out during the day but in the brooder with a heat source at night. Not for much longer cause it’s warming up here in Texas