With only 6" to work with the probably will outgrow the space pretty quickly, especially if it is a sativa dom.

You could get a second container the same size and flip it upside down on top of the other to give more room. There are several people around here that do just that.

I used a container very similar to your for the seedlings. After 3 weeks I ran out of space.

Good luck.
blink_inc Reviewed by blink_inc on . will my plants outgrow my box ok well my box has about 6in from soil to light. its a 18gal tuberwear container. I plan on flowering as soon as they get a few more nodes and lst'ing them. im still waiting to find out if they r male or female, i have three plants. so i have 3 chances to get a female. i wouldnt mind just growing one if only one turned out to be female. so will my plants outgrow my box or will they stay below the light? here is a link to my thread that has photos of my build. Rating: 5