How many plants will fit depends on what size you grow them to. There are SoG growers that put as many as four small plants in a square foot of floor space. The higher wattage the light, the further from the bulb the light reaches and the taller the plants can be. A 1000w, for example, can support up to six feet of vertical growth, not counting the bottom of the trunk where light doesn't reach very well. We grow up to 2.5' tall plants that take up 1.25 square feet each.