Benefits of Deep Watering

Lawns can survive on water twice per week

Deep watering works! The pictures below show four projects within a block of each other one month after watering was restricted to two days per week in Los Angles. The two projects on the left are maintained by Garden View, and we trained the roots to grow deep. The two projects on the right are competitors’ and obviously had not undergone deep root training.

After new plantings have sent out roots and are established, it is strongly recommended that you encourage and train the root system to grow deep. Watering every day is one of the most common mistakes made in this endeavor. In 32 years of business, I’ve observed the results of daily watering thousands of times (literally), and our company has been hired on many occasions to correct these results. I’ve also been a featured speaker on several occasions to landscape professionals, garden clubs, and concerned groups, especially during the drought several years ago.

Garden View Deep Root Trained Projects

grass with well trained deep watered roots properly trained grass roots

Competitors’ Projects One Month after Water Restrictions

dying grass due to lack of deep watering dead grass from untrained roots

Simply stated, encouraging deep root growth is universally accepted as good horticultural technique. When you water every day, the roots have no need to grow downward for water, because they have what they need near the surface without this effort. In addition, when you water daily, the subsurface becomes saturated and no oxygen or bacteria can grow. This can kill existing roots and cause fungal growth and disease, and the new roots we want to grow deep will not grow down into this over-saturated soil. The problem is that when it gets hot out, the surface is the first place to dry out. Even though there is water deeper in the ground, the grass or plants dry out because their roots are only on the surface and not tapping into the deeper water. This is when many people get caught in the catch-22 situation: “If I don’t water the plants or lawn daily, they dry out, but if I water daily, the roots don’t grow down.” Again, it is shallow-trained roots that create this problem.

One of the biggest problems of over-watering is that trees don’t develop deep root systems, and the roots of older, more mature, and larger trees may come to the surface looking for air. This can cause trees to blow over during high-wind conditions and creates surface-root problems for concrete driveways, walkways, and so on. The problem is much more pronounced in poorly draining soil, with the wet boggy soil reducing the stability of the trees in wind even more. In addition, in well-draining fertile soil, young trees (especially with fertilizer tablets installed) can grow too fast, making them leggy and weak.

Another downside of daily watering is that it encourages weed growth. Weeds—especially crabgrass—generally grow in the top layer of the soil. All seeds, including weed seed, need constant moisture to germinate. If the top layer of soil dries slightly, the weeds can’t get started, but the grass or plants can survive off the deeper roots (unless all the roots are at the surface from daily watering). A weaker grass also provides less competition against weeds.

Pink rot in the crown of palm trees is often started and/or aggravated by the humidity caused by constant watering. Oak root fungus in oak trees and crown rot in trees and plants are either started or exacerbated by watering too often. In addition, when the ground is saturated, worms and grubs often come to the surface, and sometimes raccoons, skunks, and other critters will dig up grass and ground cover looking for this food.

In fall and winter the roots are still growing but the top of the plant grows minimally. This is the best time to encourage deep roots by watering as long as is reasonable and as seldom as is reasonable. When the surface soil gets a little dry, the roots start growing downward looking for water. During fall and winter there is less chance of stressing the plants from under-watering, because the weather is usually favorable (fewer hot days and less-frequent drying winds causing wilt in the plants).

Encouraging deep root growth is a balancing act that is complicated by many factors, including but not limited to new landscaping, soil types, existing roots from trees and shrubs, plant types, plant groupings, prior watering techniques, sprinkler systems, shade, sun, slopes, drainage systems, changes in the weather, and numerous other factors. Water penetration also depends on the soil. Sandy soil absorbs water much more quickly than clay soil, and loamy soil falls in the middle. It is thus important to check your soil for absorption.

Several short watering periods done the same morning are more efficient in most cases than a single long watering. For instance, instead of utilizing one 10-minute watering period, change to a 3-4–minute watering period with three separate start times cycling one after the other.

The key is to water deeply enough that the roots grow downward for the water. Be careful though, if the plants are allowed to dry out too much, the minute root hairs (feeder roots) may die, setting back the process. Please understand that it is a process. You cannot just cut back on how often you water; you must slowly train the roots to grow down.

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