Remember you're pretty much mimicking what happens naturally in nature. Seeds fall from plants in late summer/early fall, get buried by leaves and/or snow in late fall/early winter, then stay there until they "wake up" in the spring.
Ditto stephanietx... I look at ws as doing just like mother nature except we confine and make it easier on us to then put them were we want. Plus we don't have to worry about when cleaning up the garden in early spring pulling something to then find out later it wasn't a weed... as me how I know this last part so well...teeee heeee