If they look good, they may not need to be fertilized. Sample your soil and have it tested.

Camellias facing a south wall in So. CA may not do well in extremely warm or hot weather mainly due to the reflected heat. It would help if you could provide some artificial shade such as shade-cloth during the hot summer months. The best time to begin fertilizing camellias is at the end of the blooming season, probably March for your area. One or two applications of a commercial fertilizer for acid loving plants would be adequate. Cotton seed meal is also good.

Thanks for the reply. They are doing well - but that wall may be a forthcoming problem next summer. I really hate to move them but perhaps now would be a better time if they need it.

I will wait to fertilize then until later this spring. Perhaps I worry needlessly, our summers can be quite cool and perhaps the reflected sun will not bother too much.

Bejay

Just after you fertilise, and when the soil is damp, put on a good mulch layer - something like bark/cambium, or pine needles, or old autumn leaves. About four inches in depth but keep it away from the trunks so there is clear space of about three inches between the trunk and the mulch. Extend the mulch cover to about four inches beyond the drip line of the Camellia's foliage.

They can often tolerate full sun, especially the C.japonica and sasanqua, but the mulch helps conserve moisture and also provides both root protection and food (as the mulch becomes humus) over a long time.