May Lawn Care
Quality lawns in Virginia can be challenging, especially during the hot, humid summers. Virginia is located in a transition zone for turfgrasses, and our climate can be harsh on grass in both winter and summer. Turf grass varieties fall into two categories: cool-season and warm-season. Cool-season grasses most commonly used here are Kentucky bluegrass, rye and fescue. They grow strong enough and deep enough to cope with our hot summers and cold winters and provide green winter color. Warm-season grasses, such as zoysia grass and bermuda grass, are sun tough, and drought and humidity tolerant. However, they do go dormant in the winter, making for a brown lawn until spring.
Cool-season grasses are best adapted to the Piedmont region, the Blue Ridge, and mountainous regions of Virginia, but they struggle during the heat and drought of the summer months. In the spring as the soil temperatures go into the 50s (F), they will be the first to resume active growth. Even the early spring low temperatures (including frost and snow) rarely slow the blade growth. The lush, green color we see now is the plant’s effort to quickly maximize its ability to make food, i.e., photosynthesis. The remaining winter food reserves are used to make the leaves. The root system will eventually catch up later in the spring, and usually the lawn balances out the needs for both shoots and roots.
However tempting it is to have the best looking lawn earlier than anyone on your block, altering this balance of growth between shoots and roots can cause more problems. Some ready-made programs that I call “step programs” are often sold in box stores as well as in agricultural stores. The bag contains several amendments that are labeled “Steps 1, 2, 3, 4, 5” and the instructions tell you when to put down each “step” spaced over the course of the year. Most of the “step” programs sold on the market contain higher than recommended levels of nitrogen for midspring and summer. This higher amount of nitrogen may produce a lush green lawn initially, but at the expense of the root system. The development and maintenance of a strong root system will be critical to turf success for the remainder of the season, especially when the stress of high temperatures begin.
No matter which type of grass you have, the two most important maintenance tasks to perform are mowing — to the proper mowing height — and irrigation — at the correct frequency and depth of irrigation. Have you ever wondered what would happen if you didn’t mow your lawn? We spend time and money getting it to grow only to cut it again and again. If we did not mow, the grass could grow up to 24″ in height depending on the type. As it grows, it would begin the natural process of sexual reproduction. The grass would then produce “flowers” in the form of green, wiry, stiff stems and are a major source of allergy producing pollen. After flowering, the seeds would set, ripen and fall. Wind and foot traffic then bends over the leaf blades and flower stems, making the lawn look neglected, which it is!
It would also thin out. The reason for this thinning is that the tip of each grass blade contains hormones that repress horizontal growth. Cutting off the tips with mowing removes the hormones and allows the grass to spread outward. The other obvious benefit of mowing is it makes your lawn look better. The spring mowing removes damaged and brown tips. It also helps deter weeds by keeping the turf thick with no holes for weeds to invade.
However, mowing can also be destructive. The cut end of each blade is a site for pathogens to enter. Mower blades that are not sharp will cause even more damage. Every mowing is a bit of a shock, which forces grass to put its energy into growing new leaves rather than roots. Mown grass also stores fewer carbohydrates. These carbohydrates help lawns survive stressful periods such as heat and draught.
One of the most common mowing mistakes is cutting the lawn too short. Never remove more than 1/3 of the grass blade at any one time. According to Dr. Mike Goatley, VA Tech’s turf grass specialist, cutting grass any more will “shock the plant and force it to redirect food resources from roots and stems toward new leaves.” Set your mower height at least 3” high for cool season grasses and 1.5-2” for warm season grasses. You need to mow cool-season grasses more in the spring and fall and warm-season grasses in the summer. Many people just mow every Saturday, but flexibility is the key.
Other mowing tips include the following:
- vary your mowing pattern. Always mowing in the same direction can compact the soil. Grass leans or grows in the direction it is mowed; altering directions will help keep it upright.
- avoid cutting wet grass. The cut will be uneven and the clippings will clog the mower. It also is potentially dangerous especially if mowing on a slope.
- mow slopes on a diagonal
- avoid scalping high spots if ground is uneven
- mow in the morning after the dew dries; avoid mowing when the sun is at full strength
Your lawn can live with deficiencies of nutrients and minerals, overcast days and even Virginia clay, but it cannot survive without water. How much and when it needs water are important issues if grass is to thrive. Understanding these needs starts with understanding how plants use water.
Grass plants bring in water through their roots and it doesn’t stay there long. Water is consumed during the photosynthesis process as it breaks down carbohydrates for energy. Like us, grass plants increase the metabolic process in warm weather. Unless the temperature gets so hot that the plant actually goes dormant, the hotter and drier the weather, the more water it will need to stay healthy. As the weather warms, and photosynthesis increases, plants need more water. Blades also lose water in a manner similar to human sweating in a process called transpiration. Water helps to keep the blades upright and strong as water moves up but also out.
Roots grow to find water. Deep, infrequent watering is best for a healthy root system and also reduces weeds and diseases. Do not wait until the grass is brown to water as this depletes energy reserves and stresses the grass. If you water frequently and briefly, the roots do not have to grow far to find water, thus remaining shallow. This retards root growth, which affects uptake of nutrients and leads to scraggly growth. Roots that lack moisture, stretch out looking for moisture and the structure and density are diminished. This can also leave the top growth limp.
In general, a lawn needs 1” of water/week when not dormant, especially as the temperature rises. If it is very hot outside, stay off the grass since that stresses the lawn. Placing a rain gauge outside will help to estimate the amount of rainfall. Lawns that are less than 12 months old, may initially require more frequent watering. Water early in the morning (4-8AM) when there will be less evaporation. Avoid watering sidewalks, driveways and roadways.
If rainfall is inadequate, irrigation systems or sprinklers can be used. When selecting sprinklers, select one that keeps water close to the ground where evaporation will be less. To determine how long to run a sprinkler system, place 8-10 tuna or cat food cans around the sprinkler range and let it run for 15 minutes. Measure the amount of water in the cans, and by multiplying this amount by 4, you will roughly have the hourly rate of the sprinkler.
Whether you want to help the environment or lessen your bill, water conservation is a pressing concern for all of us. If you have a cool-season lawn, you’ll need to decide whether you allow it to go dormant in the summer heat–its natural state– or if you want to keep it green by using precious resources to hydrate it artificially. Dormancy is not death but even a dormant lawn needs about 1/4″ of rain every other week. To determine whether your lawn is going dormant, look for a bluish-gray cast to the overall lawn, inward folding blades and footprints that remain when someone walks across the lawn. Do not fertilize under these conditions as that causes additional stress.
Tips for better watering
- Collect rain water in cisterns or rain barrels to use for irrigation
- Water the lawn early in the morning (4-8AM)
- Take into account how much rain has fallen
- Pull back on watering when the weather is cloudy and overcast or there’s high humidity and little wind
- Water more if there are long periods of intense sunlight, high winds, dry conditions and warmer-than-usual temperatures
- Avoid large spring applications of fertilizer — this lush lawn will require more water
- Use timers connected between the spigot and the hose end in order to be sure sprinklers only run the minimum amount of time. It is too easy to forget that they are on.
- With our clay soils, it is nearly impossible to do 1″ of water at one setting. Split it into 1/2″ of water 2 times/week.
- Core aeration can loosen compacted soil allowing water to infiltrate deeper, but do this in the fall
- Consider more drought-resistant grasses such as warm-season grasses
Remember that everything we do to our lawns and landscapes affects local water quality and that of the Chesapeake Bay. For further assistance, call the Help Desk of the Albemarle/Charlottesville unit of the Virginia Cooperative Extension Office at 434-872-4580.
A Lawn to Dye For-How to Create a Perfect Lawn: Mowing Your Lawn by Shawn Askew, Virginia Cooperative Extension publication at http://pubs.ext.vt.edu/CSES/CSES-39/CSES-39.html
Spring and Summer Lawn Management Considerations for Cool-Season Turfgrasses by Mike Goatley, Virginia Cooperative Extension publication at http:pubs.ext.vt.edu/430/430-532/
Summer Lawn Management: Watering the Lawn by Mike Goatley, Virginia Cooperative Extension publication at http://pubs.ext.vt.edu/430-010/
Peterson, Chris, The Complete Guide to a Better Lawn. 2011