veggin plant til 6-8 inches..how big of pot do i need?

veggin til my babies get to about 6-8 inches what size pot should i get that will last me til harvest? 1.5gallon pot? or 2 gallon pot?
Ps growing under a 400w hps hortilux bulb

3-5 gal............

at least a 3 gallon and remember your air roots get them exsposed to air near the trunk

3 Gal will be fine