Your grow area is about 2.6 x 4.5...that's about 11.75 square feet. I'd go with two 250w over a single 400w. With a room that's more rectangular than narrow, the farthest areas of the room will be pretty far from the bulb if you've got one 400w in the center. You can get the 250w a little closer to the plants, too. You'll have slightly less heat issues. Try and get a clip light and mount it on something that is up high and near the door...and have it blowing out. That will at least get some of the (rising) warm air out. I've grown in an area like this, and here;s the good news...the extra height helps a lot with keeping things cool. My 02.

btw...I don't know what you call "small" plants...but 11.75 square feet is enough to get 6-8 good sized plants. I'm talking about 32-40" tall plants. I've grown four decent size plants in a 28" x 28" area. I'm interested in hearing how other feel, but I'd be thinking about 6 plants in a space like that. 16" x 17" for each plant would be 32" x 51"... pretty much exactly what you described. 16" x 17" is enough room for a plant that ends up around 3 feet tall.
Roughrider Reviewed by Roughrider on . Light Recommendations/Issues for this space The space available measures 2.62ft wide (standard door size basically), by 6.5ft length, by 7.4ft high. Due to some shelves and a slight decrease in height towards the back, the area im looking to grow in equals about 2.62 x 4-4.5ft x 7.5ft high, which is towards the front of this area. What would the best setup be in this space, using a HPS light and non-hydro/garden pots setup? I was thinking a single 400/430w lamp to grow either two nice plants, or 4 slightly smaller ones. I can Rating: 5