Mine are big, old established P. bipinnateifidiums about 8ft tall and wide, living under big oak trees. They get filtered sunlight all day. They get supplemental water from the irrigation system in the spring and fall, and only what rain Mother Nature provides in summer. I've never fertilized them, as I don't really want them to get much bigger . .
Despite my best effort, the one in the pic put up a nice new leaf this month.
In a pot, I'd think it would help the plant if you can sink the pot into the ground under a tree that gives filtered light. This would insulate the roots from the hot daytime temperatures. In CA with your lower humidity, I'd think they'd do well with a good watering every second or third day. But bumping up the humidity around the plant would sure help it a lot. A quick spray with the hose around the plant once or twice a day - or whenever you walk by - would do the trick.
