You said that you had a 4' x 6' area in your closet? With the lighting that you described earlier, you have enough room for 24 plants, giving each 1 sq. ft. of space. Otherwise put however many you want in there, but space them evenly so that you are getting the best use of your light. Also, that way every plant gets evenly lit, and you can trim them to be bushier if the garden isn't fillind out. By the time they are 3' they could be bushy enough to fill that space, even if you have only 4 plants.
