Yes, Evelyn, that's about when I do annuals too- late March or early April. The annuals sprout fast when weather is warm, and unlike perennials, they grow fast too.
For late frosts I generally flip the jug lids closed and cover all the jugs with a sheet. For a really hard freeze I sometimes put them in my unheated garage overnight. Perennials tolerate it fine on their own, though.
I sometimes "wintersow" in summer, too. I use the milk jugs with more vents and keep them in mostly shade. It works well for perennials or biennials which don't need cold strat. They get planted out in fall and bloom in the following summer. Much easier than starting them indoors. What I really have against indoors is all the sterilizing trays and cells, it's a pain.
Karen
