Bigger is better! I use 10s now, but you may have trouble with your space. Do 7s if you can, and yup.... Super crop that bad boy! Mine did fine.
Here they are today a few hours before lights out. A little thirsty they got watered yesterday. I'm up to just about daily waterings now in the 1 gals. Getting ready to upsize soon. I was planning on 3 gals but I do have 5s. I may have to super crop that tall one