How big of a plot are you planning? I am putting a mix of oats, rye, and peas here in the next week or so. The oats will frost out but will be a good draw early with the peas and then the rye will stay green all winter. You dont have many options at this point. A brassica mixture is a good winter source, but you had better get it in pretty quick. They require 90 days before the first frost, and your pretty far north. I got my brassica plot in on 8/6 and i plan to do the grain mixture over labor day weekend. You could split it and do both like i did.