Here is a question we received this past week from our Weekly Watering Number listserve:
Our HOA has a lot of grass that we would like to keep green and usable for recreational things like walking or playing Frisbee. What mowing height would you say is right for us to aim for and do you have any idea how much your watering number would be reduced if the lawns were mowed as high as 4"?
Great question! It is true that keeping your lawn taller will help shade the plant’s roots and hold moisture in, but there is a point where the amount of leaf structure will cancel out any benefit you get from shading. For cool season grasses, the best bang for the water buck is to cut at about 2.75 to 3 inches. Of course, if you don’t want to measure the length of your grass, you can start by adjusting your mower to its highest setting and see how that works. It may take you a couple of trial runs to figure out the length that works best for your situation.
Is Your Lawn Earning its Keep?
Ah, the American lawn. It is as much a part of our national tradition as apple pie and baseball.
Look into any community across the nation, and you are likely to see lawns incorporated into our home landscapes, parks, recreation fields, and more.
And, why not? When planted with thoughtful design, lawns can be a beautiful and practical addition to the landscape. There are also many great benefits to planting grass.
But, lawns also require more water and maintenance than many other plants. Up to 50% of water used to maintain lawns can be lost to evaporation, runoff, overspray, and overwatering.
So, is your lawn earning its keep? Take a moment to evaluate your lawn. If you think of it as more of a hassle than a haven, you may want to consider changing your landscape to better suit your needs - perhaps incorporating lawn alternatives, waterwise plants, or hardscapes.
On the other hand, if your lawn is a haven, you may be able to save water, money, and time this summer by making some small adjustments to your regular maintenance routine.
Benefits of Lawns
There are many benefits to planting lawn in landscapes. Proper soil preparation and routine maintenance are crucial to maximizing these benefits.
Aesthetics: Lawn is versatile and functional. A well-maintained lawn and landscape can increase property value and create a sense of community pride. And, it is ideal for foot traffic because it withstands trampling more than any other type of plant.
Recreation surface: Lawn provides an excellent surface for all sorts of outdoor activities - picnics, sports, play space, etc. It is also a delight to walk on!
Reduces runoff and soil erosion: Lawn is one of the most effective plant materials to reduce runoff and prevent soil erosion. With up to 90% of the weight of a grass plant in its roots, it’s no wonder grass is very efficient at erosion prevention.
Cooling effect: Lawn surfaces reduce temperature extremes by absorbing the sun’s heat during the day and by slowly releasing it in the evening, thus moderating temperatures. The cooling effect of an average lawn can equal more than eight tons of air conditioning (the average home air conditioner produces four tons of cooled air).
Absorbs dust and other pollution: With their extensive and intertwined system of leaves and roots, grass surfaces around the world are estimated to trap some 12 million tons of dust and dirt from the air annually. In addition, grass takes carbon dioxide out of the atmosphere and replaces it with oxygen. Grass is such an efficient carbon dioxide–oxygen converter that an area 50 feet by 50 feet generates enough oxygen to meet the needs of a family of four.
Lawn Maintenance Requirements
Whether newly planted or well established, lawns need considerable maintenance including proper soil preparation, aeration, fertilizing and mowing in order to be green and healthy.
Soil preparation: Healthy soil is the foundation to healthy plants, including lawns. In fact, grass receives three of its four key ingredients (air, water, and nutrients) from the soil. Healthy soil also helps plants to be naturally resistant to disease and pests.
The first step in healthy soils is knowing what you are working with. You can easily find this out by taking soil core samples from several areas of your yard and have them analyzed. Check with your local garden center or Extension Office for commercial soil testing resources.
Aeration: Aerating your soil in the spring or fall (or both, if you can) each year promotes moisture infiltration into the soil, efficient use of fertilizers, and promotes better root growth. Use a rented power aerator or garden fork to aerate your lawn. Then overseed with a rye/fescue mix designed for Pacific Northwest conditions and top dress your lawn with about a quarter inch of fine compost to improve the condition of soil and allow for better water retention.
Fertilizing: Fertilizing can encourage healthy root development and replace essential nutrients lost through leaching and transpiration. If a soil test or plant performance indicates a need, use organic or slow-release fertilizer in late fall or late spring. Organic and slow release fertilizers release nutrients over a longer period of time and are less likely to run off your lawn into waterways after rain. They also support the variety of soil organisms that improve fertility and combat diseases.
Mowing: The general rule of thumb is to mow often enough that it is only necessary to cut a third of your grass’s total height. Adjust your lawn mower to a higher setting. A taller lawn provides shade to roots and holds soil moisture better than if it's closely clipped. It is also important to use sharp blades to prevent tearing and injuring your grass.
Considering a Lawn Alternative?
The Pacific Northwest has many spectacular native, hybrid native, and other plants adapted to local climate and soil conditions. Once established, these plants are very low maintenance, require little to no pesticides or fertilizers, and survive well on available water.
Depending on your site’s growing conditions and how you would like to utilize your landscape, you may want to consider one of the following alternatives to lawn:
Alternative Seed Mixes: Another popular alternative to turf has been the emergence of alternative lawn seed mixes used for areas that traditionally have been dedicated to turf grasses. In general, alternative lawn seed mixes contain low growing, drought tolerant plant varieties that require less mowing and irrigation once established.
Groundcovers: Groundcovers come in a wide variety of textures and colors, and some have interesting features like flowers and berries. Once established, groundcovers typically require much less water than lawns. In fact, some groundcovers can actually be planted in a way that will mimic the appearance of a traditional turf lawn without requiring water, fertilizer and maintenance in general. Many varieties can be walked on or used as foot paths due to their cushion-like feel and durability.
Shrubs and Trees: Shrubs and trees can provide dramatic impact to the way we experience a landscape. Unlike turf, trees can eventually provide shade and protection from the wind. In winter, deciduous trees will allow light to penetrate and help illuminate and warm structures.
Shrubs and trees are available in virtually limitless sizes, shapes, textures and colors. Shrubs and trees add structure and definition to a landscape and greatly enhance the habitat opportunities for local wildlife. Once established, they generally require much less water than a lawn, and in some cases, no supplemental irrigation is required after roots are deeply set.
Hardscapes: Hardscapes are a great way to enhance your yard. The use of rocks, concrete and wood for pathways and patios adds texture and areas of interest to your landscape.