Cool topic, Annie! The examples you give are such good ones, and a reminder to me of how dependent we've become on instruments (e.g., 'plant Caladium bulbs when the soil temperature is x degrees outside'), as opposed to observing and understanding nature's own signs.
When I lived in CT, the forsythia blooming in March was always the first sign that spring was about to begin.
In October and November, the signals of autumn were flocks of Canadian geese honking and migrating overhead in Vs, along with the fall foliage colors, which would begin turning about midSeptember and peak the 3rd week in October.
I guess I know seasonal signals, but have not yet learned nature's signals for different planting times.
