San Diego does not have four conventional seasons — it has a wet cool period, a dry warm period, and two transitions. Working with that rhythm saves water and keeps plants alive.
Fall and winter (October–February)
The most important season here, and the one most people ignore.
- Best planting window of the year — winter rain establishes roots for free
- Cut irrigation run times by 50–70% or shut down after rain events
- Clean drains, catch basins and downspouts before the first storm
- Prune deciduous fruit trees in January; hold off on frost-tender plants
- Refresh mulch before the rain so it settles in
Spring (March–May)
Gradually increase irrigation as evapotranspiration climbs. Fertilize actively growing ornamentals lightly. Prune spring-flowering shrubs right after bloom. Do weed control now — every weed pulled in March is a hundred seeds you don't fight in June.
Summer (June–September)
Peak water demand, and prime failure season. Walk every irrigation zone monthly. Add shade before you need it, not in the middle of a heat wave. Avoid heavy pruning on stressed plants, and avoid planting entirely unless you can commit to hand-watering.
Watch for the September Santa Ana pattern — deep-water established trees a day before an event and skip the overhead spray.
Frequently asked
- When should I overseed or resod?
- Cool-season lawns: October. Warm-season lawns: late spring, when soil warms.
- How often should I change my controller?
- Four times a year at minimum; a weather-based controller does it automatically.
- Best time to hire for a build?
- Design in summer, build in fall and winter — you get better scheduling and the planting establishes with the rain.