Container gardeners get more benefit than moisture from a soaking rain; the water can help wash away salt build-up in the soil from San Diego’s imported water. But a downpour can also be deadly to container plants when drainage holes are clogged with roots or the plant is severely root-bound.
Check containers after every rain to be certain plants aren’t sitting in water. If you discover accumulated water, tip the container to drain the water away and remove the obstruction, if possible. Allow the container soil to dry out, moving it to a sheltered spot if more hard rain is forecast. On the other hand, when rainfall is light, container plants may not be thoroughly wet and may need additional water. Check soil moisture using your finger. Soil a couple inches from the surface should be damp, not wet nor too dry.