Problem
Why does my california Lilac have yellow leaves?
Ceanothus × delileanus 'Gloire de Versailles'
Yellow leaves on a california Lilac usually has one of three causes — watering, light or a pest. Walk through them in order before reaching for a treatment.

Most likely causes
Detailed cause-by-cause guide is being prepared. In the meantime: check watering rhythm, sunlight match, and any visible pests on the underside of leaves.