Water with Purpose

It’s a no-brainer: All plants need water. But how much and how often varies from plant to plant. While there are various recommendations 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 encourage these water applications for the following plant types:

  • Lawns — A half-inch of water once a week is sufficient for lawn survival and modest growth.
  • Groundcover, perennials and shrubs — Plants such as 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 3/4 inch per square foot, or about 1/2 gallon per square foot, per watering event.
  • Trees — Established native and adapted non-native trees rarely need any supplemental irrigation. If one month significantly lacks normal rainfall, then the recommendation is 1 inch per square foot, or about 2/3 gallon per square foot, once per month.
  • Palms — Established palms only need water once a year, at most.

The proper use of recommended watering amounts and schedules will produce healthy plants and reward you with lower water bills.

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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Find expert advice on garden basics, landscape design, watering and year-round maintenance.