As long as they have 2+ months to veg, they'll be fine. Strain dependent, obviously, but you need to allow 2+ months to flower as well... so you need a solid 4 months of suitable outside weather. This is trickier in say FL (born n raised) due to crazy RH. Just check your freeze dates if you even have any... don't let them get colder than 54 degrees and don't let them burn up either :) hope this helps you out. I would however suggest that you run autos.. then seed to harvest is 3 months and then you won't need to worry at all. My opinion though, it's not too late at all. Lots of guys wait til mid may. But I want trees, so I started early lol