Seasons and Dates

2012 - although the variances between years are so minor it doesn't matter
source: http://aa.usno.navy.mil/data/docs/EarthSeasons.php

Spring

March 20th - June 19th

Summer

June 20th - September 21st

Fall

September 22nd - December 20th

Winter

December 21st - March 19th

General guidelines

source: http://www.digitalseed.com/gardener/schedule/vegetable.html

• Cool weather crops (leafy greens, winter squashes, peas, brassicas, etc.) sown outdoor October - February
• Warm weather crops (tomatoes, beans, corn, etc.) sown outdoor April - August
• See source document for exceptions