The valve is directly wired to the transformer on the low voltage side. The mains voltage side of the transformer the plugs into that Zwave relay from Amazon.

Remote control activates the Zwave AC output. Transformer gets power and in turn feeds lower voltage AC to the solenoid valve. Valve turns on, water flows.

If you stick with generic sprinkler control stuff then you can use the commonly sold 24 volt irrigation transformers, some of which are rated for outdoor and water exposure. The 24 volt irrigation valves are usually rated for outdoor exposure and water.

The key to reliability is that the actual electrical connections on both the full mains voltage AC wiring and the low voltage AC wiring connections must be sealed against moisture and corrosion.

Corrosion happens fast in outdoor installations so sealing and intelligent installation are critical.

Winterizing a basic traditional in-ground irrigation system is not terribly difficult. I use a rather compact air compressor but a larger rental or borrowed unit makes the job go faster. Rig up a hose to adapt between the air compressor outlet fitting and the garden water hose bib feed connection.

Use the compressor to pressurize the feed-in end of the irrigation system, then open one irrigation zone valve at a time. The compressed air flow simply forces the residual water through the buried tubing and out the spray heads. The compressor just needs to have enough oomph and CFM to move water from all the low lying pipe sections and carry it up and out the spray heads.

Cycle through all the zones one at a time until only a fine mist is still visible from any of the heads. Cycle through all the zones once more to be sure. Shut the compressor off, you are done.

Disconnect the air hose and cap the water feed inlet until spring.