I'm just starting my first grow and am doing 2 northern lights. It was mentioned that 2 of these may make it crowded. We will see. It makes me wonder though if it's crowded will it affect the yeild? Looking down the road I already have seeds of Girl Scout Cookies, Blue Dream and White Widow and I'm not sure if it would be better to just do one of each or if these strains size is OK to grow two in this size tent.
Learn to scrog(lst), and super crop and loli pop. You will be good then. All that means is make a net, and when the plant gets too tall, you hold the branch down in the net, lets the other shoots catch up. Super crop, you damage the outer stem(maybe do on your next grow or becareful). And lolipop, thats where you trim every thing under the scrog net, so you will only have colas in your small space. Best luck.