I had a Ray Hartman Ceanothus that got water similar to yours. It lasted about 2 years, then it started yellowing and in the heat of one August it cooked and dried. I dont plant anymore ceanothus in areas where any sprinkler water can get to it. They seem to like watering the first year by hand and then left alone after.

It is difficult to tell from a picture. Leaves are not permanent and all will be replaced in time. I doubt it is a watering problem. My Carmel creeper has creeped into an area getting regular water and seems happy there. Ceanothus is very sensitve to roundup so be careful of over spray which will kill the whole plant. From what I can see I think your ceanothus is growing normally considering your soil. Al

I think it's just the normal leaf drop as the plant goes into "summer dormancy" as so many of our natives do.

wanda

Thanks. I put a different sprinkler head on today so won't get watered anymore directly but that doesn't stop the roots from getting some water. I noticed a couple branches almost completely bare. I guess I'll cut those back some.
Now I just have to remember in winter if not enough rain to water them...

Ceanothus love good drainage--they usually grow on hillsides--so yours may just be showing the effects of being in heavier soil than they're used to. In zone 18 you should never have to water established ceanothus, especially in clay soil.

Where you are, you are much more likely to lose a ceanothus to root rot than to drought.

My 'Concha' ceanothuses (ceanothi?) on a hillside got plenty of water, too much, actually, and they did great. They were monsters. Perhaps the drainage is more important that the watering?

I agree hoovb, the drainage is probably more important.
All the advice says good drainage but then I have read not to amend natives. So that is confusing especially when I tell the nursery it's rock hard clay. Plenty of rocks and sometimes it's like digging into granite. They say that's ok just throw it in there.
So after digging the holes before planting, I filled with water and only took about 15 minutes to drain.
I have read concha and my tessjara blue can tolerate some summer water. My carmel creeper is on a slope with nothing watered above it but gets sprinkler overspray. My concha are in their own watering zone so that is easy to control and were just put in last fall. They did flower a little this spring but of course still receiving water. A friend has yankee point which gets tons of water for 15 years now.

I agree with Wanda. I have quite a few ceanothus, along with cistus, rosemary and sages. They all have yellow leaf drop. All of their energy had been focused on their flowering - now they are doing their summer dormancy-thing.