How often to water citrus trees in California

In July, established citrus trees in loam need a deep watering about every 8 days in the Central Valley, about every 11 days on the south coast and about every 9 days in the South Inland zone. Sandy soil holds less water, so waterings come closer together. Clay stretches them. Check the soil before each watering and skip one after a soaking rain.

In July in the Central Valley, established citrus trees need about 6.8 gallons a day under a 10 foot canopy and about 27 gallons a day under a 20 foot canopy. Give it in deep waterings spread days apart rather than a little every day, so the whole root zone gets wet.

Yes. WUCOLS rates citrus trees separately for each of the six California climate zones: moderate water in the North-Central Coastal zone, moderate water in the Central Valley zone, moderate water in the South Coastal zone, moderate water in the South Inland zone, not suited to this region in the High and Intermediate Desert zone, moderate water in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.

Yes, and it is one of the most common ways home citrus fails. Constantly wet soil suffocates the shallow feeder roots and invites root rot: leaves yellow and drop even though the soil is damp, and bark near the soil line can darken. Let the surface dry slightly between soakings and keep water off the trunk.

For the first season the tree can only drink from its original root ball, so water right over it and keep it evenly moist through the first summer. Check it often in warm weather, since a small root ball dries much faster than the surrounding soil. As the tree establishes, widen the watered area and shift toward deeper, less frequent soakings.

Drip works very well as long as it covers enough ground. A single emitter next to the trunk is not enough for a tree; use a ring or grid of emitters under the canopy and move them outward as the tree grows. Run the system long enough for water to sink deep into the root zone instead of just wetting the surface.

Check the soil before reaching for fertilizer. Soggy, poorly drained soil yellows citrus leaves and makes them drop, and cold wet winter soil can trigger yellowing between the veins even when nutrients are fine. If the soil is drying properly between waterings and the yellowing continues into warm weather, a nitrogen or iron shortage becomes the more likely cause.

Some drop is normal: citrus sets far more fruit than it can carry and sheds the extras in late spring. Heavy drop beyond that, or fruit that splits in late summer and fall, usually traces back to moisture swings, long dry spells followed by heavy soakings. Steady, deep watering on a regular rhythm is the fix, not more water overall.

Citrus is evergreen and keeps drinking a little all winter, so do not shut the water off completely. In most of the state winter rain covers the need, and irrigation is only for long dry gaps between storms. There is a bonus to not letting the soil go dust dry: moist soil holds daytime warmth and gives the roots some protection on frosty nights.