Utah is an amazing place to live with good infrastructure, a strong economy and world-class outdoor activity venues. But the climate requires irrigating the landscapes. The water from natural precipitation does not typically provide enough moisture through the summer. As the weather warms up, people start irrigating lawns and gardens.
Most years the spring rain, and sometimes snow, provide enough soil moisture for our landscapes. There should be no rush to start watering landscapes and gardens. To encourage proper lawn root development and summertime health, the best practice is to wait to water for as long as possible in the spring. This typically means that our landscapes will not require watering until May and sometimes not until mid-May. This practice allows grass roots to grow deeper as they look for water already available in the soil, and in turn, helps keep our lawns healthy and avoid stress when the heat of summer arrives.
As far as your outdoor watering goes, the adage "more is always better" does not ring true. There is a misconception regarding how frequently lawns in our climate need to be watered. Lawns do not need water every day but knowing how often and for how long to water can be a challenge. To help, try envisioning your soil as a reservoir from which plants can draw water using their roots as little straws. Water exits that reservoir by either traveling down through the soil and going below root depth, moving up into the air through evaporation, or through the plant tissues via roots and stems through transpiration. The rate at which all this loss occurs depends on several factors, but during the spring and fall, the rate at which water is lost is much less than in the hot summer. Knowing how much water your soil holds and for how long it is held there allows you to know how long to irrigate and how often. Once you know how long to irrigate, you only need to adjust the frequency of irrigation as the seasons change.
How long should you water your lawn?
A general guideline for irrigation cycles is to apply ½-inch of water each time you irrigate. For the average soil that is enough to fill the root zone (the top 4-8 inches of soil where most of the roots are) without overwatering. To know how long it takes to apply ½ inch, put out an empty soup can in the middle of the area being irrigated and then measure the depth of the water in the can after you irrigate.
Adjust irrigation time up or down to get about ½ inch. If your sprinkler system is not applying water evenly, the measurement in your can could be off compared to the rest of your yard. For a more accurate reading, use multiple cans spread out and take the average amount of water collected after irrigation. This is a simple process that can be done easily without a lot of training.
Once restrictions have lifted and recovery from COVID-19 has taken place, you can also take advantage of the Weber Basin Water Conservancy District’s free water check program. This program is available for those within Weber, Davis, Morgan, and Summit Counties. They are performed by District staff who will come out to help evaluate your sprinkler system to determine how fast water is being applied, how uniform the coverage is and leave you with a customized schedule. Call 801-771-1677 to schedule an appointment (This is not available yet for 2020, availability is yet to be determined).
Another option to get a more exact measurement of irrigation rates and uniformity, would be a catch cup test. Follow this link to learn how to do it yourself from the Center for Water Efficient Landscaping: http://www.cwel.usu.edu/watercheck
How long it may take to apply ½ inch depends on the type of sprinkler heads and nozzles you have and how your system has been designed. There are two general types of heads; rotors (includes impact heads) and fixed pop up spray heads. Rotor (and impact) heads have a stream of water that moves back and forth over the area being irrigated. Spray heads pop up and spray a fixed fan pattern over the area. These usually put out water at a faster rate than rotors for the area being covered. It may take as few as 8-10 minutes or up to 20 minutes for spray heads to put out a half an inch of water and could take 30-60 minutes for rotors and impact type heads.
For those with heavy clay soils or who are trying to irrigate hills, try the cycle and soak method. To do this take the total amount of time you need to water to put down ½ inch, and break that into 2 or 3 shorter periods, then allow 30 minutes to 1 hour between each short cycle so that water can move into the soil without runoff. You still apply the total amount needed in one day, but you have put it into shorter cycles with soak time in-between.
How often should you water your lawn?
How often you should water is nearly as complicated as how much, it depends on your soil type, which plants are being watered, and the overall weather conditions.
Soil type factors into how often you need to water because varied soil textures hold onto water differently. One particle of sand is about five hundred times larger than one particle of clay. This means that one cup of clay has much more surface area than once cup of sand. The more surface area a soil has the more water clings to it, decreasing drainage and increasing water-holding ability.
What does this mean for your watering schedule? If you have clay soil you will need to water much less often than those that have sandy soils. Those that have loamy soils, which means a good mix of clay, sand, and organic matter will water somewhere in between.
Weather conditions also play a significant role in how often you might need to water. The warmer it is the more frequent the irrigation will be, however, there is no need to water every day in most situations. Doing so encourages grass roots to remain shallow and encourages thatch, both of which complicate irrigation and make lawn dry up when it is too hot. The exception to this may exist in very sandy, or rocky soils where short, but more frequent irrigation may be needed. The schedule below can provide some general guidelines for how often you may need to water your lawn during the growing season.
These are general guidelines to try and help you have a healthy lawn and reduce excessive irrigation. Your soil, irrigation system, and landscape are unique to you. If you follow these guidelines and your lawn has a hard time staying green, make small, incremental adjustments to your schedule to find the right time and frequency needed. If your lawn has been watered every day in the past, its roots are going to be shallow and it will take some time to train them grow deep, a little bit of stress on your lawn will encourage this. Try tapering off slowly. After a little while of watering as infrequently as possible your roots will be deep and your grass more drought and heat stress-tolerant.
It is also a good idea to check your irrigation system regularly for broken, tilted, or incorrectly aligned heads. Sometimes the yellowing and dry spots in our grass are because of poor uniformity or inefficiencies in our system. Minor adjustments to the sprinkler heads can fix these issues, do not assume more water is the answer. If you do have one or two spots that are always a problem, consider watering these spots individually one or two more times a week with a hose rather than running your whole zone longer or more frequently or look for alternative ways to improve sprinkler coverage in those areas, such as moving a head or changing a nozzle to get more uniform coverage.
A healthy lawn requires paying attention to irrigation, proper fertilization, pest control and proper mowing practices. When lawn growth slows down in the summer or the dark green turns a little lighter, know that this is normal for cool-season grasses and does not mean the lawn is dying. Other lawn stressors could be bugs, fungus, or simply lack of water due to poor sprinkler system performance. Because we live in an arid area that requires irrigation, we encourage you to follow these guidelines for proper landscape irrigation.
You can also consider some great alternatives to lawn that require much less water but still provide the attractive landscape you want. To learn about these alternatives visit www.weberbasin.com to check out all the garden resources, visit www.localscapes.com to learn how to have a landscape that fits into our local climate and also visit www.WeberBasin.com/Conservation/ClassCalendar for classes and other resources to help you achieve water savings in your home and yard.