Wireless latch valve controller help

I’m guessing my situation is unique but I’ve got 4 separate gardens that I need to water, due to the geography of my property they are pretty far apart. There is a hydrant next to each one so I have water but I don’t really want to run control wires all over the place. What I would like to do is build a wireless controller that can turn a latch valve, like an Orbit 58874N, on and off. Since my gardens are spread out and don’t have power nearby I’d like to use LoRa or some other low powered communication protocol and power everything from solar. My thought was I would run OpenSprinkler on a master node in the house and have it tell each of these slave nodes then to turn on and off. I don’t mind getting dirty with code or breaking out the soldering iron but I’ve never designed a PCB before. I think OpenSprinkler has all the parts I need to make this happen but I’m not sure where to start with re-arranging them. Any help getting started would be greatly appreciated.