As a rule of thumb in hydro...DWC, you can use 5 gallon buckets or 10 gallon sterlite tubs...1 plant per tub...or make a recirculating system, Grow a MUM, and clone it...veg until plants are 12-18" tall, then flower. this allows you to grow more plants smaller, and acheive the same grams per watt or sq. foot or whatever you are shooting for. If you want trees from seed..then you have to go thru sexing, and that will end up requiring as many as 3 grow spaces...whereas with cloning, you can use a small cloning area, and veg them 'til you need them. sorry, rambling on