Lithops

Lithops

I just bought a couple of lithops the other day. I live in the San Fernando Valley in Los Angeles. It gets pretty hot here in the summer and I was wondering since the conditions here are dryer than most places, how often should I water them? They are outdoors and in full sun. I have been searching google for a while, but I have seen varying advice. The sides of the lithops seem to be wrinkling a little bit. Should I water? Thanks in advance.
My Scandinavian home

My Scandinavian home

A Case for bush (dwarf?) beans

A Case for bush (dwarf?) beans

Bottle brush tree

Bottle brush tree

Pineapples

Pineapples

Still growing.

Still growing.

Flowers in my Garden

Flowers in my Garden