Hi there A little shade will not do any harm but they can do well in full sun. Mine gets sun all day but I keep an eye on the plant during summer. Last summer it suffered burned leaves after a couple of days near 40 degrees C. I learned from that and built it a shade cloth protector which I used successfully on two 42 degree days last month. I think far more important issues to consider are drainage and soil. My waratah is in a raised bed and in a mixed soil of clay, loam and sand. I pruned it right back after it flowered (late September) and the plant took off. I keep it well organically mulched (lucerne) The temperature ranges here are a mid-winter low of -2 up to summer highs of 34 and the occasional 40+ with a good deal of humidity. Hope that helps you in California.
Telopeas graw naturally around Sydney on sandstone soil. They are an understorey plant, but still like a fair bit of sun. The ones I have seen in the bush are usually in a small clearing, where the sun can filter in quite easily. They require excellent drainage, but a good supply of moisture. Not sure how they will go in a medeteranian environment, because they apparently don't grow so well in southern Australia. Worth a try however. Note that they are generally slow growing, so you have to be quite patient.
