Evelyn, this is my 6th year wintersowing, so I've come across a little of everything.
I have had sprouts killed off by late freezing weather, when I first started. They were tender annuals which had sprouted in early warm weather, then they bit the dust when the cold returned. I've never had that happen to things that are perennial or hardy annuals here. To avoid that, I sow my perennials and hardy annuals in winter. I wait until later, closer to spring, to sow the tender and half hardy stuff. This includes my tomatoes and flowers like zinnias, marigolds, cosmos. I haven't sown those yet this year. I'll be doing them in the next 2 to 4 weeks, depending on the weather and forecasts. Then after those things sprout, if we have late hard frost, I'll throw an extra cover over them overnight. I don't worry about covering the perennials or hardy annuals.
Consider this: We just had a week with highs if mid 50s to high 60s for a week. That's enough to make zinnias and tomatoes sprout. But the low tomorrow night will be 28. I'm gad I haven't sown anything tender yet.
Karen
