Efficient lawn watering

What happens to water you put on your lawn? Water can be used by plants, evaporate from the soil or percolate down through the soil to the water table.

The most efficient watering system for a lawn is to water it only when necessary. Check the amount of moisture in the soil about three inches under the surface with a screwdriver or small Garden trowel. If the soil is damp, there's no need to water - even if the surface soil looks dry.

To determine the rate at which your sprinkler system applies water to your lawn, place several small containers in the area being watered. Run the system for 15 minutes, then measure the depth of water in all of the containers and average them. Multiply the average by four to determine how much water is applied to the lawn per hour.

Typical lawns should receive at least one inch of water per week. When you do water, don't apply water too quickly. Heavy clay soil can only absorb about one-quarter inch of water an hour. That means that this type of soil should be watered more frequently with smaller amounts of moisture.

Finally, avoid watering during the heat of the day. Water early in the morning or in the evening. If you have an automatic sprinkler system, water during the night; our climate is so dry that night watering doesn't create problems unless you overdo it.

Fall and Winter Watering

by J.E. Klett and C. Wilson¹

Quick Facts...

• Water trees, shrubs and lawns during prolonged dry fall and winter periods to prevent root damage that affects the health of the entire plant.
• Water only when air and soil temperatures are above 40 degrees F with no snow cover.
• Established large trees have a root spread equal to or greater than the height of the tree. Apply water to the most critical part of the root zone within the dripline.

Dry air, low precipitation, little soil moisture, and fluctuating temperatures are characteristics of fall and winter in many areas of Colorado. There often can be little or no snow cover to provide soil moisture, particularly from October through February. Trees, shrubs, perennials and lawns can be damaged if they do not receive supplemental water.

The result of long, dry periods during fall and winter is injury or death to parts of plant root systems. Affected plants may appear perfectly normal and resume growth in the spring using stored food energy. Plants may be weakened and all or parts may die in late spring or early summer when temperatures rise. Weakened plants also may be subject to insect and disease problems.

Plants Sensitive to Drought Injury

Woody plants with shallow root systems require supplemental watering during extended dry fall and winter periods. These include European white and paper birches; Norway, silver, red and Rocky Mountain and hybrid maples; lindens, alder, hornbeams, dogwood and mountain ash. Evergreen plants that benefit include spruce, fir, arborvitae, yew, Oregon grape-holly and Manhattan euonymus. Woody plants benefit from mulch to conserve soil moisture.

Herbaceous perennials in exposed sites are more subject to winter freezing and thawing. This opens cracks in soil that expose roots to cold and drying. Winter watering combined with mulching can prevent damage.

Lawns also are prone to winter damage. Newly established lawns, whether seed or sod, are especially susceptible to damage. Susceptibility increases for lawns with south or west exposures.

Watering Guidelines

Water only when air temperatures are above 40 degrees F. Apply water at mid-day so it will have time to soak in before possible freezing at night. A solid layer (persisting for more than a month) of ice on lawns can cause suffocation or result in matting of the grass.

Plants receiving reflected heat from buildings, walls and fences are more subject to damage. The low angle of winter sun makes this more likely in south or west exposures. Windy sites result in faster drying of sod and plants and require additional water.

Monitor weather conditions and water during extended dry periods—one to two times per month without snow cover.

Newly Planted vs. Established Plants

Newly planted trees are most susceptible to winter drought injury. Woody trees generally take one year to establish for each inch of trunk diameter. For example, a two inch diameter (caliper) tree takes a minimum of two years to establish under normal conditions.

Trees obtain water best when it is allowed to soak into the soil slowly to a depth of 12 inches. Methods of watering trees include: sprinklers, deep-root fork or needle, soaker hose or soft spray wand. Apply water to many locations under the drip line and beyond if possible. If you use a deep-root fork or needle, insert no deeper than 8 inches into the soil.  As a general survival rule, apply 10 gallons of water for each diameter inch of the tree. For example, a two-inch diameter tree, needs 20 gallons per watering. Use a ruler to measure your tree’s diameter.

Newly planted shrubs require more water than established shrubs that have been planted for at least one year. The following recommendations assume shrubs are mulched to retain moisture. In dry winters, all shrubs benefit from winter watering from October through March. Apply 5 gallons two times per month for a newly planted shrub. Small established shrubs (less than 3 feet tall) should receive 5 gallons monthly. Large established shrubs (more than 6 feet) require 18 gallons on a monthly basis. Decrease amounts to account for precipitation. Water within the dripline of the shrub and around the base.

Herbaceous perennial establishment periods vary. Bare root plants require longer to establish that container plants. Plants transplanted late in the summer or fall will not establish as quickly as plants planted in the spring. Winter watering is advisable with late planted perennials, bare root plants, and perennials located in windy or southwest exposures.

 

 

Mowing guidelines

Mowing practices can greatly affect turfgrass health. The two most important factors are mowing height and frequency.

The preferred height of Colorado turfgrass species is two and one-half to three inches. Grass plants undergo less stress when the amount of blade left on the plant can still function efficiently. The minimum height is two inches. Mowing grass to a height of less than two inches can reduce drought and heat tolerance, and cause a higher incidence of insect, disease and weed pest problems. Scalping is never recommended, nor is there any reason to change mowing heights during the year.

Mow the lawn frequently enough so that no more than one-third of the grass blade is removed during a single mowing. This requires changing your mowing schedule to reflect how quickly the grass grows. This can range from four to ten days between mowing.

Clippings left on the lawn can be beneficial to the plants and save mowing time. Clippings break down quickly, which allows nitrogen and other nutrients to be recycled. Clippings can also encourage the growth of beneficial soil microorganisms. Studies show that it takes less time to mow more often and leave clippings on the lawn than to mow less often and catch and bag clippings for disposal.

Mowing equipment should be well maintained. Sharpen blades after every third mowing, or, at the least, once a month.

 

Patchy lawn

Thin grass is often a sign that a lawn has not had enough fertilizer or water, the soil is too compacted, there is too much wear and traffic on the lawn, or the lawn has a disease or insect problem.

It is important to first diagnose the cause of the thinning lawn and proceed from there. Pest problems are usually the least common reason for a thin lawn, while improper fertilizing, watering or mowing are the most common reasons. Excessive traffic from children or pets is another common cause.

Once the cause has been determined and treated, routine lawn management will thicken the grass back up. The process can be shortened if the thin areas are aerated and over-seeded with a good quality seed.