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These guidelines are based on local research from the University of Arizona and expertise from our Zanjeros (conservation specialists) to help you understand how often and for how long to water your landscape. Scroll down for more detailed monthly watering guidelines.
Once you establish a run time that gets water to the root zone of your plants, keep the run time consistent throughout the year and add or subtract the number of waterings, depending on the season. Check out our Monthly Watering Guidelines below for more detailed watering recommendations for specific plant and soil types.
Assumptions: These guidelines are based on using 2-gallon per hour drip irrigation and Tucson’s most common soil type, Sandy Loam. If you have clay-type soil, cut your waterings in half and double the run time; consult our monthly guide for more details. If you have bubblers instead of drip irrigation, you’ll need a much shorter run time. If your drip emitters put out more or less than 2 gallons per hour, per plant, adjust run time up or down.
Exceptions: Newly planted vegetation, vegetable and flower gardens, potted plants, and shallow-rooted plants and annual flowers usually need more frequent waterings. Cactus and succulents in the landscape need very little water after establishment; rainfall is usually enough to keep them healthy.
When it rains, give your irrigation system a break and skip watering. Smart controllers and rain sensors will do this automatically. All landscapes will benefit from mulch around the plants, which helps retain soil moisture and reduces water used by plants.
Poor irrigation scheduling is one of the problems regularly seen in commercial and residential landscapes. Plants that get watered too frequently for short periods of time often develop very shallow root systems. A better strategy is to apply more water, but wait longer in between waterings. This encourages the roots of plants to grow deeper into the soil where evaporation is less. Plants with stronger root systems are stronger above ground and can withstand more extreme weather conditions.
- Large trees need more water and should be watered longer to reach deeper roots (3 feet). Shrubs should be watered to 2 feet deep.
- Avoid watering from 11am – 4pm when evaporation is highest, but do set the system to run when you can monitor it. We recommend a start time of 6am.
- Landscapes and irrigation systems require regular maintenance like many things in and around our homes. Do a manual run of your system once per month and walk it to look for leaks and stuck valves.
- At a minimum, irrigation controllers should be re-programmed twice per year to adjust for the varying water demands of plants in different seasons.
Landscapes require care and maintenance to ensure that vegetation stays healthy and disease free. Routine maintenance procedures should be performed based on flowering cycle, seasonal growth cycles, and as needed. Seasonal maintenance generally includes pruning, fertilizing, adjustment of irrigation scheduling, and applying herbicides/pesticides. As-needed maintenance is generally removing/replacing dead and dying plants and damage done due to natural climate-related causes or human accidents. This guide provides best management practices and tips for homeowners and professionals alike.
All plants, even those adapted for our desert climate, have varying water requirements throughout the year. Water by the Weather - Landscape Watering Guidelines is a local watering guideline for landscape professionals and homeowners alike. The guide provides information on determining soil type and watering system components and helps determine the most efficient monthly watering schedule for your landscape, based on plant and soil type.
Resources for helping with plant selection and the watering needs of plants are:
The Low Water Use/Drought Tolerant Plant list compiled by the Arizona Department of Water Resources for the Tucson Active Management Area
Landscape Plants for the Arizona Desert by the Arizona Municipal Water Users Association
- Drip Irrigation: The Basics by Ursula Schuch
- Turfgrass Consumptive Use Values for the Tucson Area by Paul Brown
- Overseeding Winter Grasses into Bermudagrass Turf by David Kopec and Kai Umeda
- Managing Spurge in the Landscape by Kelly Young
- Weed Management in the Landscape
- Mulching: Materials, Applications and Performance