"Vince" wrote...
The sprinkler has six zones, and almost always, thus
far, it was shut off during zone 5 because the GFCI outlet tripped.
Then, barely a few minutes later, the outlet was tripped again. Now, I
cannot even reset the outlet - the reset button keeps popping out, even
with the sprinkler unplugged. If I waited a few hours, then I can reset
it and plug the sprinkler back in. I have replaced the GFCI outlet, but
the new one is doing the same thing. Is the sprinkler box the culprit?

Sounds like the GFCI is doing its job! There is probably a current leak
somewhere in the sprinkler system that is exacerbated by the water. When it
dries out, you can reset the GFCI again.

GET IT FIXED BEFORE SOMEONE GETS ELECTROCUTED!