Grow season is determined by first hard frost, generally. I don't rush getting the plants out early. Up here on the Canada border they can go out May 1st, if you're lucky and it's not too cold and/or wet. If you start them indoors you can wait until July 1st and still have time to get four weeks of veg outdoors before they start to bud. June 1st is when our veggie gardens normally go in around here.
That said, success growing outdoors is very strain dependent. You want strains that will finish in 8-10 weeks as most strains will usually start to bud the beginning of August and by the middle of October the good growing weather is done, frost or not.