No room !!

Hey just a question I have 4 girls in veg in a 2 x 4 tent and I want to flower them naturally outside but being in Canada it' still cold I was hoping to put them out in June July ish but what my best option when the start getting to big I'm on A 18 on 6 off light schedule would making that shorter help out at all and how short should I make make it last option is to trim them down when the time comes but I really don' want to do that thanks for the feed back !

you can fim them which will slow the upright growth for about 2 weeks like topping and it will start to make them branch out at lower nodes,you can also super crop the tops and tie them down some just to buy you so time,looks like it will get cramped some but think you can manage for a while