I want to let my chickens do all my brooding this year but we live in a colder climate. When can I let my hens set? It is nice today but we are going to get more sub 0 temps this next week. They will be kept in the barn when it's cold. We had chicks last of August last year that did just fine but we had some very cold days when they were young. The end of August is the latest we can hatch outside.