Quite the hodgepodge mix for me. Shoulder season is a mix: Primarily Aspen and Jack Pine with some fir and red pine mixed in. Winter is: Primarily Red Oak with some Birch and Red Maple mixed in. Last winter was our first burning here at the new house. We went through a TON of shoulder season wood. There wasn't really a plan, it was just grab whatever whenever. This year I have the Red Oak in its own stack waiting for the true cold season.