I'd say 4 to 10 depends on whether you want to lst scrog or sog
DamianLucifer Reviewed by DamianLucifer on . How Many Plants Should I grow!!! I have a 3 or 4'x21/2'x5' area that I am going to use a 400W HPS. I was woundering how many plants I should grow to get the most out of my light and plants. I dont wana take away any lighting from plants by crowding the area. What do you think will be the proper number. Peace, Sensisaint Rating: 5