Autumn Equinox?

So... is the Autumn Equinox when outdoor plants flip to flowering?

according to this site: http://www.timeanddate.com/calendar/september-equinox.html, since i am in s.cali, the date is September 22nd for this year. Which is when there is equal daylight/night.

No, doesnt mean shit. It's all genetics

In round numbers, photo plants will flip to flower when the nights get longer than 10 1/2 hours. That will vary by strain a great deal as more breeders breed for a lighter light trigger due to mold, early frost and other reasons. But everyday from Summer Solstice to Winter Solstice the days are getting shorter. When the nights get to the magic tripping point for the strain you are running, that is when they will start to flower. Talk to growers in your area who are running the strains you are, and find out when their plants usually flip. Many of the New England growers are already in flower. Being down here in NW Florida, I'm still vegging away.