I made an incredibly similar project earlier this summer that's been humming along quite nicely for a couple months now.
I used 12V 1/2" solenoids from AliExpress that were about $4 each and control them with a custom PCB I made that has mosfets on the board to run the solenoids from a pro-mini. I also added a rain-sensor so it can adjust the watering schedule accordingly.
There is also an NRF24L01 integrated on the board so it can communicate with NodeMCU's inside to get time, report status, enable wireless control, etc. But I haven't actually implemented that portion yet.
In case you're interested, I attached the PCB outline below.
Pro-Mini SOT-232 MOSFET Wireless RGBW Driver_INVERTED.pdf (172 KB)