My friend tried to grow this bougainvillea variety as a ground cover, pegged shoots to the ground, sheared off vertical growth, plants looked healthy for a while but are not looking good lately with scrawny new growth and puckered mature foliage. Can anyone diagnose what is going on? I should also mention that originally there was a lawn here that did fine. Lawn was ripped out and replaced with ceanothus that struggled mightily, one plant dying after the next. Bougainvillea (planted more than a year ago) is not dying but looks sad. The area where it is planted is a small, gentle slope.
I see a couple of things going on, and can suggest further investigation and some things to try.
Plants look overall quite pale, yellow-green, not the deep, rich green common to most Bougainvilleas. I would try a complete fertilizer. Especially knowing there was a lawn there. Grasses are very efficient at grabbing all the nutrients in the soil. Puckered or mis-shaped leaves can also be from nutrient deficiency.
I see large bites out of the edges of the leaves. This might be from a 'bug' that lives in the soil most of the time, or hides under the leaves in the daylight. Go out at night with a flashlight and see if you can see the critter. If you are not adverse to using pesticides you might end up using a bait or spray for the 'bugs', but it depends on what is causing the problem.
Other problems that might be considered, given the history of the area:
Lawns are often treated with herbicides that are active against broadleaf weeds (dandelion, spurge, oxalis and many others). Ceanothus and Bougainvillea are also broadleaf plants and might be affected by weed killers used on the lawn.
If the lawn had been killed by Round Up or other herbicide this might have an affect on the Ceanothus, though not likely to linger long enough to affect the Bougainvillea.
Ceanothus must have superb drainage and minimal water. Was the irrigation altered (timing and duration) from whatever schedule the lawn was on?
Did you add any soil amendments when you removed the lawn? What sort of soil prep did you do for the Ceanothus then the Bougainvillea?
Are you using any sort of mulch on the soil surface? Mostly this is good, but there can be some problems
Good: Holds water, acidifies the soil, encourages beneficial organisms, moderates soil temperature.
Bad: Harbors pests, can remove too much nitrogen from the soil as it decomposes.