Water with Purpose

All plants need water. But how much and how often varies from plant to plant.

Although there are various recommendations floating around out there, we prefer to rely on scientifically based advice.

Knowing there can be slight variations based on soil, shade, slope, season and species, we recommend no more than these water applications per the following plant types:

  • Lawns — One half-inch of water once a week is sufficient for lawn survival and modest growth.
  • Groundcover, perennials and shrubs — Plants like jasmine, ivy, salvias, lantana, roses, yaupons and hollies do well with twice a month watering in the absence of rain. The amount is never to exceed ¾ inch (or ½ gallon) per square foot, per watering event.
  • Trees — established native and adapted non-native trees rarely need any supplemental irrigation. If a month significantly lacks normal rainfall then the recommendation is 1 ¼ inch per square foot, or about 1 gallon per square foot, once a month.
  • Palms — Established palms only need water twice a year at most.

The purpose of appropriate watering schedules and amounts is to produce healthy plants and low water bills. Plants need both water and oxygen to thrive and grow. Too much of either results in poor performance.

Picture of Mark Peterson
Mark Peterson
Mark A. Peterson was a conservation project coordinator for San Antonio Water System before retiring. With over 30 years of experience as an urban forester and arborist, Mark is probably the only person you know who actually prunes trees for fun. When not expounding on the benefits of trees and limited lawns, you're likely to find him hiking San Antonio's wilderness parks or expounding on the virtues of geography and history to his friends.
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