"Won't require repotting or a lot of other care."

Anything grown in a container will require periodic repotting as well as additional attention to watering and fertilizing . Otherwise, they will decline and become rootbound and stunted and the foliage will become sparse and patchy.

Both ceanothus (California lilac) and Morella californica (Pacific wax myrtle) are ideal choices for rocky, gravely soil and are CA natives. They can be easily maintained at the height you want and are frequently recommended as hedge plants.

And far easier to grow in the ground as opposed to a container.

Thank you, I'll look into those.

I concur that "won't require repotting" is unrealistic; I should have said "won't require frequent repotting." I have a couple of plum trees in pots (the reason is too complex to go into here), and they have to be repotted every couple of years.

I agree that growing this kind of plant in the ground is preferable to pots, if the plants don't mind.

I just did some research online, or tried to. There are umpty-seven varieties of these plants, and I didn't find any sites that compare them in an easy-to-use format.

I did find a site (https://greatplantpicks.org) that tabulates characteristics of each variety. I learned that Ceanothus Victoria wants to grow into a mature plant that's 12 feet high and 15 feet wide. Morella Californica wants to grow 15 feet high and 15 feet wide.

I'm afraid both of those are non-starters because I'd have to trim them continuously. If I put them where I want to, trimming the front of the hedge would mean working in a space that's a foot or two wide, part of which is next to a 15-foot drop. (The rest is next to my garage's metal roof, which is not intended to be walked on and might be damaged if I fell on it.) If I plant it farther from the edge I'll block off maybe 1/4 of the plantable space in my front yard. Neither option is attractive.

If there are other varieties of these plants that naturally grow only 3 or 4 feet high, they'd work. Particularly the wax myrtle, which is very attractive because it provides food for birds. But as I said, I couldn't find information about varieties in a form that would let me search for ones with particular characteristics.

I was also staggered by the prices. I saw 3-gallon wax myrtles offered online for prices like $64.99. Walmart was offering ten smaller ones for $47.98, but it looked like a time-limited sale.

I was thinking of something like rosemary. I know there are many varieties with different habits. I once saw an office building surrounded by a solid planting of rosemary that was knee- to waist-high, and I'm sure no one was trimming it, because it was growing too thick to get into.

Another option occurred to me: have a fence built along the edge of the area and plant some kind of vine in front of it. The vines will grow to the top of the fence and no farther. I already need to replace an old fence along the part of this space that isn't next to the garage roof. Extending it further would cost only incrementally more.

Grapes? I already have grapes growing on a frame over a garden walkway, and I'd enjoy having more. I know they're not meant to be grown that way, but... why not? They'll drop their leaves in the winter (zone 14), but the stems might afford enough privacy. I'm not going to go naked out there, I just don't want anyone walking by to have a clear view of the yard and house. If the fence isn't too high, perhaps I could safely trim the vines on the outer side by leaning over it. With a long tool.

A photo of both sides might help us see what your situation is, the betterv to help you. Once or twice a year trimming is usually enough to keep most things in bounds.