Deep watering entails watering at a slow pace for long enough that the water soaks deep into the soil, where the roots are. Often this means watering for 30-60 minutes at a time, 2-3 times each week, until plants are established.
Generally, deep watering means that the soil is saturated to about an 8-inch depth. Healthy plants usually grow their roots down deep. In fact, some plants grow roots that are nearly two feet long for optimal nutrient and moisture uptake.
To determine how long you need to water to get one inch, place a plastic container in your yard and set a timer. On average, it will take 30 minutes to get a half inch of water. So, 20 minutes, three times per week will give a lawn about an inch of water.
For example, spray sprinklers should run for about 2 hours weekly, ideally split into three 20-minute sessions, while rotor sprinklers may need 1 hour weekly, divided into two 30-minute sessions. It's best to water more deeply and less frequently, especially during hot, dry spells, to encourage deeper root growth.
Deep watering is when the soil and roots beneath your turf, tree, and shrubs are saturated at least several inches below the surface. Lawns require more water than other types of turf due to more extensive coverage of the area and more susceptibility to stresses like heat or foot traffic.
Your goal is for the lawn to receive enough water to keep the soil slightly moist in the upper six inches of soil. This usually requires at least one inch of water per watering session or around 30 minutes of watering, however, each lawn is different.
Run the sprinklers for 20 minutes and use a ruler to measure (in inches) the depth of water in each can. To determine the average depth of water applied to the lawn, total the water depths for all of the containers and divide the total amount by the number of containers you used.
For example, rotor sprinkler heads might require 20 to 30 minutes of straight watering time, while a traditional spray head zone will only need 5 to 10 minutes.
Watering 101
Your lawn needs 1 to 1 ½ inches of water per week. A typical in-ground sprinkler system provides ½” of watering, per zone, in a half an hour. This would mean that you need to run each zone of your sprinkler system for 30 minutes, 3 times a week to sufficiently hydrate your lawn.
The average system uses approximately 15-16 gallons per minute, per station. Here is an easy formula to help you calculate the approximate amount of water you are using each month.
A fixed spray head nozzle might take ~30 minutes to apply 1 inch of water, whereas a rotary nozzle could take 3x as long to apply the same amount. But this still depends on numerous variables such as local water pressure, age of the sprinkler system, condition of the system, etc.
1-2-3-2-1 watering technique:
In April water 1 day/week. In May ramp up to 2 times/week. In the heat of the summer water 3 times/week. In September drop back to 2 times/week. In the fall drop back down to 1/week.
Editor: Since pots and pans vary in sizes, covering something with two inches of water means there should be two inches of water covering the top of the food, not that there are exactly two inches of water in the pot.
Generally, light, daily or frequent irrigation keeps the top one to three inches of the soil moist, while deep, infrequent irrigation waits for signs of the grass wilting before applying enough irrigation to wet the soil to a depth of 10 inches or more.
Water less and less frequently while increasing the amount of water as the plant matures and/or develops deeper roots. Several short watering periods spaced out across the morning are more efficient in most cases than a single long watering.
If it is not raining, the lawn can need as much as 1 hour for rotor zones and 10-15 minutes on spray zones. We recommend watering 3-4 times per week. If you still notice dry spots, we recommend supplemental watering in between regularly scheduled water times. During the fall your lawn still needs water.
Sprinklers should be set to run for about 30 to 35 minutes at a time twice a week.
Watering in the morning also helps your lawn stay cooler throughout the hottest parts of the day, decreasing the amount of heat stress for the turf. If you are unable to water in the mornings, early evening (between 6:00 PM and 8:00 PM) is the next best time.
Water Wisely
Many of us water too often and too long. Most lawns need to be watered no more than three days a week in the spring as well as in the summer and two days a week in the fall. This watering schedule is recommended under normal water supply conditions.
A typical sprinkler system with pop-up rotary heads uses approximately 15 to 16 gallons of water per minute per station. An Irrigreen smart sprinkler system uses approximately 6 gallons per minute per head when spraying about 30 feet.
If your grass is actually dead, there's nothing you can do to bring it back other than plant new grass. Brown grass, however, can green up following proper care. Oftentimes, that just means water, nutrients, and cooler temperatures for northern lawns and warmer temperatures for southern lawns.
There's no cut-and-dry definition of a deep watering. Most gardeners generally refer to it as when water has soaked at least eight inches into the soil. This gives plants the structure required to survive lack of water, whether from a drought, a busy gardener, or other environmental stresses.
The most common and fastest way of measuring ocean depth uses sound. Ships using technology called sonar, which stands for sound navigation and ranging, can map the topography of the ocean floor. The device sends sound waves to the bottom of the ocean and measures how long it takes for an echo to return.
It is defined as the pressure exerted by a column of water of 1 inch in height at defined conditions. At a temperature of 4 °C (39.2 °F) pure water has its highest density (1000 kg/m3). At that temperature and assuming the standard acceleration of gravity, 1 inAq is approximately 249.082 pascals (0.0361263 psi).