Predators are used in large greenhouses: http://www.thanetearth.com/faqs-pesticides.html http://www.thanetearth.com/faqs-pesticides.html > With outdoor plants,

Predators are used in large greenhouses: http://www.thanetearth.com/faqs-pesticides.html http://www.thanetearth.com/faqs-pesticides.html > With outdoor plants, there are so many natural predators to pests that things tend to form a balance. Although you're not looking for balance, you're looking for a huge abundance of a single crop. > In addition to that, yes, there is the world's most abundant (and inexhaustible) energy source just sitting there waiting to be used. That energy source doesn't work quite so well if you start stacking things vertically and isn't necessarily reliable. Reducing inefficiencies in growth may be more beneficial than saving some power.