We live in a "shadow of the mountain" microclimate where there is very little precipitation so every thing must be watered. I am currently flooding my pampas grass with water from the koi pond. I'm guessing it gets about the equivalent of an inch of precipitation each week. Average lows will drop below freezing many nights this winter and every few years may stay below freezing for several days in a row.

I was wondering when should I taper off my water to my pampas grass? Should I base it on length of day, average temperatures?