I've been experimenting with mirror's (acrylic mirror pieces) placed under plants, I'm growing (4) in a cabinet and (2) have mirror's placed below them around the stalk, these (2) are 7 inches @ 4 weeks and very, very bushy compared to the (2) without mirror's and contain large amounts of under growth, this may be worth a try for you.
No Expert just havin' fun.....:rastasmoke: