A little Java App that calculates daylight hours based on latitude. http://astro.unl.edu/classaction/animations/coordsmotion/daylighthoursexplorer.html could be helpful this fall.
While that's cool and all.....flowering outdoors begins much sooner (up to a month) than the equinox. So it's not really an acurate gauge of flowering time. Just sos yous know. asssit:
yeah, it's cool and all but you do realize that 12/12 is sept 21/22 no matter where you are on the planet. put the day-of-year slider on sept 21/22 and then slide the lattitude slider around. and as Psycho D said, flowering does not start on day 1 of 12/12. my plants always start flowering around the 2nd week of august and finish in october.