We also studied ceanothus (Family: Rhamnaceae; Genus: Ceanothus), which I have in my garden as well, mostly for the bees but also because they are beautiful. Most of these genera also prefer lean soils; coastal sage scrub or chaparral communities. Again, they survive in my garden, likely for the same reason the manzanitas do - I plant them in dry areas and leave them alone. However I have lost a few ceanothus, and I think it's because those were in areas that received irrigation. I also pruned one of them very heavily to keep it out of a path, and eventually it bit the dust. Though it's true ceanothus are naturally shorter-lived than manzanita, because they are nitrogen-fixers; like legumes, they pull nitrogen out of the air and put it into nodules at their roots. All nitrogen-fixers live brief lives, I suppose because they are working so hard while they are alive. Many ceanothus prefer coastal conditions, but quite a few like it hotter and drier, and I guess I lucked out by choosing those varieties.
I'm sharing all this because I know many of my readers are also lovers of California native plants, and like to make space for them in home gardens (which is a noble pursuit). Here's what I recommend you do (and what I'll be doing as I plant in future): Take a lot of time to research the plants before buying them. Most nurseries give cursory information about planting at best. For native plants, there are a few good resources that will help you determine the best placement for a plant (and perhaps whether even to buy it at all). These resources are: Las Pilitas Nursery, San Marcos Growers, California Flora Nursery, Native Sons Nursery, the CalFlora website, and the Jepson Herbarium website from UC Berkeley. These websites will help you understand what the ideal planting conditions are BEFORE you plant.
A word about plant communities: I've known about them for many years, but I can't say I have planted according to them, to my garden's detriment. Let's take my yard as an example. It is flat, it is comprised of clay soil, it gets extreme temperatures (over 100 many days of the summer, below freezing many days in winter), it is extremely dry for most of the year (if not irrigated), and is surrounded by streets and concrete. It has had an inordinate amount of organic matter mixed in as well as been covered by wood chips. Some of it is shaded by very large, mature trees, and there is a lot of leaf litter. Some of it gets no shade at all. There are microclimates within its boundaries; some areas stay wetter and cooler longer, some are ovens with hot, trapped air (by the way, the ceanothus and manzanitas are located in the oven sections, that probably helps them). I have to be brutally honest about the basic conditions of my yard in order to have planting success. There is no sense in having a coastal or island plant in my garden. It will not survive.