Will someone please tell me what this means?
RE: From seed; stratify if sowing indoors
Most perennials and some hardy annuals need a cold period before they can germinate well. You can winter sow them, but if you don't want that you can stratify them. Here you can read how it works.
http://www.canadiangardening.com/how-to/seeds/how-to-stratify-seeds/a/1972
Jonna