Here's what San Marcos growers say. I think much would depend upon your soil.

https://www.smgrowers.com/products/plants/plantdisplay.asp?plant_id=3968

I have this plant in my hot, dry, inland garden and I really do like it! It is planted against my garage and gets full sun, along with plenty of reflective heat. Are your plants in full sun? If not, this may be contributing to your problem. Also, they prefer to have good drainage.

In my garden, I probably water it once a month in the summer. I can tell when it needs some water because the leaves start to droop. Unfortunately, it is frost sensitive in my area, so I had to cut my plant back pretty hard in February. It recovered slowly and it is now about 2'x2' and in full bloom. I have read they don't really like to be pruned and based on my experience I would have to agree. I intend to put a frost cover on my plant this winter, so I don't have to prune it again. However, if your plant isn't looking healthy, I would give it a light prune. Try and cut back to an active bud which should encourage it to push out a new branch. The recovery process may be slower than you would like but it should help.

Good luck!

Interesting - the San Marcos site says it can be planted in light shade in hot inland areas (we are East LA) and it will have a more open habit - it is shaded part of the day - planted on the southwest facing side of the house. So perhaps that accounts for it. A couple of years ago it was much denser with bigger leaves and so many blooms. The thing that changed actually is that we got a ton of rain last winter....so it seems like it was denser with more blooms during the dry years before then. I wonder also what the life span is. Thanks for your thoughts!

It probably will tolerate light shade, but it is a desert plant so ultimately it probably flowers best in full sun. I wish I could have it all over my yard, like you do, but due to the frost in my area, I can't. I have to limit the plants I cover and this is one of them, for sure :) Best of luck to you.