I've decided to install some sort of fertigation system in my new greenhouse. The water is being supplied by 3/4" high pressure PVC to three individual valves assigned to three individual zones. 1 of the 3 zones is for a small orchard (5 or 6 trees) and the remaining 2 zones are for raised grow beds in a 1,000 sq. ft. hoophouse type greenhouse. My struggle has been designing a system whereby I'm able to use one fertigation system to separately fertilize each of the three zones. It seems this should be possible using ball valves and so forth but I'm having difficulty with the actual design. Should I have the fertigation system (EZ flow for example) before the valves in the high-pressure section of the water line or should the system be after the valves in the low-pressure part of the system?

Does anybody here have any experience with fertigation inside a greenhouse who could weigh (ore anybody else with experience/ideas) in on this with any suggestions? Your help would be appreciated. Thanks!!