with a 400 watt light I would leep the plants under 3 foot you will not get good enough light penatration for any taller of a plant. If you had better lighting then yes a 4-5 is going to yeild more but with less light all the bottom will be scragly shit that is pretty useless for anything other than hash. I have always found that in any given sq footage if fully covered in canopy whether you have 5 bigger plants or 10 smaller plants it will yield pretty much the same it all really depends on your light.
u.g.u Reviewed by u.g.u on . hight/yield ratio Just harvested my first buds since building my growroom(s). I let my two plants get really tall (4-5 feet). I'm using a 400W HPS for flowering, and a seperate room with 4 ft. flourescents for veg. I have my second batch in veg right now and they're 7"-8". What is the optimum height to move them to the flowring room? If I flower 4 plants that are 1 foot tall, will they yield as much bud as 2 plants that are 3 feet tall? Just trying to figure out how to maximize my output. Does Rating: 5