I sowed hardy perennials in late Sept/early oct. some have germinated and are tightly packed in the pot. I think it is too late to prick them out. Will they survive in my plastic greenhouse? I have each pot in a ziplock freezer bag which is open now, but I can close over the winter. I have overwintered older seedlings(from summer sowing) in plastic boxes with snap lids before. this is my first attempt at autumn sowing. Should I do anything else?
Many seeds do well when sown fresh in late summer and autumn. If they germinate early, they can be pricked out. Late germinatiion can be thinned and left to prickout later and many do not sprout in autumn but do so in spring.