I have a side yard full of
Tree Philodendron (Thaumatophyllum bipinnatifidum) at our rental property growing in the shade of taller trees and one growing on the opposite side of the house in full hot Florida afternoon sun without any problems but I also have one here at this house in a container, it's a cultivar that's been on the market the past few years Philodendron 'Hope':
http://www.south-florida-plant...
http://www.plantdelights.com/P...
When I left 'Hope' in full sun, the leaves looked identical to your plant! I find that this Philo loves moisture and high humidity as the other P. bipinnatifidum but prefers more protection from direct sun. Since you are in California where you don't get much rain during the year, I'd say you might want to water a little more often than once a week but also move it to a shadier location.
