I don't think it's too late to sow PSB right now, though getting borderline. Charles Dowding in his organic vegetable growing book says best to sow early July to avoid pests.
I usually do it in May but didn't get around to it and love them large, but a lot of people around my plot don't set them out til late July or even August. They get smaller plants but they are closer spaced. Not sure which way gives a better yield - I'll be finding that out this year hopefully. Mine are just germinating now, but in soil blocks a la Eliot Coleman so there's no check on growth on planting out.
My next door neighbours don't put theirs out til late July either, and one of them was in the land army during the war so she knows a thing or two about vegetable production ;) Mind you she was surprised when she came down my lottie and saw my mighty towering versions.
