Thanks! It’s a pet project 
requiring care & feeding every now & again.
Check out this project and search Google for SmartThings, sprinkler, irrigation: ESP8266 Smart Sprinkler System
My recommendation is to actually have two NodeMCU modules because they’re cheap. The reason for TWO is because you want to alleviate yourself from maintaining your own version of my code and just use my prepared stock code from here to eternity. For $3.50 on fleebay, it’s a simple choice. Otherwise you’ll be copying quite a bit of logic from me which is not simple or easy. Remember that for automating (like turning it on/off at certain times like irrigation systems require) SmartThings is limited to only automating the main “capability”, switch in our case… and hence the reason why I needed to create a SmartApp to synchronize the secondary switch to a virtual/fake one. Otherwise no automation worked. In your case, you’d do that for 3 separate switches. Not easy at all…
Lastly, don’t be too cheap as you’ll pay for it all in your time investment & long-term maintenance. I love my RainMachine Mini8. It was super-simple to install & run. I’m very happy with it and how smart it is adjusting water amount based on local weather/rainfall/humidity, etc.