Larkspur were my best examples of hardy annuals sown in fall. They grew to be big, sturdy, beautiful plants. The ones sown in winter or spring never got to half that size.
Here are volunteer larkspur in my yard in January. Yep, that green are all larkspur, seeds dropped by plants the summer before. Reseeding was such a problem I had to evict larkspur from my yard.
Karen