Turfgrass Management Practices
By Tom Del Conte
Former President Northern California Turfgrass Council
Founder Del Conte’s Landscaping 1972, Vision Recycling 1993, SprinklerTimes.com 2011
Growing a nice turfgrass is all about the cultural environment that
you are able to create for the grass type desired!
When growing any plant material there should be a significant effort to create an environment conducive to the plants being grown. Turfgrass is no exception and may even be an extreme example of this concept as turfgrass is merely a large sampling of many plants grown tightly together over an area. The concept of “Natural Selection” is substantially at play in turfgrass areas. Because of the relatively short root depth and herbaceous nature of each of the grass plants which make up the turfgrass stand, turfgrass responds rapidly and decisively to the cultural conditions imposed. Therefore to have a very nice stand of turfgrass it is important to understand and control the cultural factors affecting the grass.
Like most other life forms, the elements which determine the health for turfgrass are, in this order, 1) medium to live on (or in), 2) water, 3) air, 4) food 5) competitive factors and 6) environmental conditions (temperature ranges, shade/sunlight ranges, and traffic).
There are a great variety of turfgrass species and cultivars available for consumers these days. Each of the varieties has varying tolerances to the elements within their living space. Because of this wide variation of grass selections and the differing tolerance to conditions the consumer should take care to understand what they want from the turfgrass and the conditions at force.
To create the best turfgrass, some of the cultural elements can and should be controlled, like managing the water amount, or removing a tree for more sunlight, aeration etc. Further, because there are so many varieties, the best choice of grass species should be selected to provide the results the consumer desires. Plan accordingly to the extent possible.
When purchasing grass seed, you will select a general type of grass. Typically within that general type, you will receive a wide variety of seed blends with many cultivars (sub-species) of the general type of grass you purchased. This will be displayed on the official seed label. This variety in the seed mix is a good thing and very important to you. As stated earlier, Darwin’s theory of natural selection will be at work in the millions of grass plants you sow. Don’t worry, the general type of grass you purchased will grow and the cultivars will figure out for themselves, which ones will grow best in that particular part of your yard. You will usually not be able to tell the difference.
There are two different basic or general types of turfgrasses which are referred to as 1) Cool Season Grass or 2) Warm Season Grasses. It is best not to mix or blend these general types. There is a good description and pictures of both types in the Plant Selection video within SprinklerTimes.com programming.
The Cool Season Grasses are mostly upright grass plants and will stay actively growing and vibrant through the summer and down to temperatures near freezing. Near and below freezing these grasses go dormant. Though to keep them active as temperatures near 35 degrees, you must keep the fertilizer active in the plants before it gets too cold. The most common types of cool season turf grasses used are Kentucky Blue Grass, Perennial Rye Grass, and Fescues. Each of these comes in a variety of cultivars which have been bred to favor different conditions. As stated earlier, the cultivars will figure out for themselves which of the subtle differences in your garden they prefer, and they will grow accordingly.
Warm Season Grasses are mostly horizontal growers such as Bermuda grass and St. Augustine. These are dominant in the southern half of the United States. Where temperatures remain moderate all year, these warm season grasses will stay green all year. However, in marginal areas where cool season grasses are vibrant all season, these warm season grasses will go dormant and brown as average monthly temperatures fall below 50 degrees.
Medium to Live on: On occasion when seeding a new grass, I have seeded beyond the target area and several inches onto an adjacent driveway. While the seed enjoys the cool moist concrete for germination purposes while it is watered on a new planting regime, the lack of root zone into a medium will condition the seedling die on the first day the water is withheld. Grass will grow on just about anything, but it’s ability to sustain through a range of normal conditions will depend upon how well established it’s life support root system is. If the soil media is friable, loose, and has organic material, it will be a live soil with good microbial activity and very conducive to root growth. For grass the top 6” of soil is important. Good soils will have about 15% organics blended or about 2” of compost mixed into 6” of soil. This is preferably done at installation, but there is evidence that top dressing, especially after aeration can get the organics distributed into the soil via worm activity. Healthy friable soil makes for good turfgrass root activity which makes for a good life support system.
How much water is being used? Water should be replaced in the root zone in the same amounts that it is depleted. The amount of water used or depleted from the plant is measured by Evapotranspiration (ET). Simply ET is the amount of water that evaporates from the soil region plus the water that transpires from the leaf tissue. Transpiring for plants is like perspiring for humans. Evapotranspiration is measured in inches of water exiting on a daily basis. ET is also expressed cumulatively over weeks, months or years. For instance the average ET in San Jose California in June is 6.2” of water exiting the plant and soil. The ET number is available in most areas via the internet or local weather information sources. This ET number should then be factored by a plant or grass type factor which is 60% to 80% of the raw ET amount depending upon the grass type. SprinklerTimes.com has an on board data base for every zip code in the US for every month to calculate how much water is used. SprinklerTimes.com automatically applies a crop factor to each grass and plant type to determine how much water is being used, by that plant type, in that zip code, in that month. WOW!
How much water to put on? Now that we know how to determine the inches of water that has exited, we want to replace that amount. Each type of sprinkler type has a different delivery rate. Some sprinklers will apply ½ inch of water in an hour while other sprinklers will apply 2 inches in an hour. This is just like the National Weather Service, this is called the Precipitation Rate. SprinklerTimes.com has a data base of all sprinkler types to calculate output from each type of sprinkler system.
Knowing the inches of water requirements ET for each month, and knowing the output of each sprinkler type, SprinklerTimes.com can calculate the run times for each system and plant type and provide the minutes of run time for each and every month.
Watering the correct amount for a lawn is also very important. Over watering will keep the turfgrass green for sure, but it will also promote other problems. Over watering is essentially placing more moisture in the soil than the turfgrass prefers. There are other plant types (certain types of weeds) which prefer these conditions and thus over watering will favor those weeds over the turfgrass in an over watered condition. Conversely, by watering properly for turfgrass, there is a narrow rang of plants or weeds that can survive with that amount of water. Proper watering, not over and not under watering, gives the competitive edge to the lawn over weeds.
SprinklerTimes.com is the tool to use to get your watering schedule on track in any zip code in the US.
Other watering tips:
Set the pressure to your sprinkler system down to a level to prevent misting. Misting will allow precious water to drift off target. Most sprinklers heads are designed to operate and have larger droplet size at the lower pressure. You can install a pressure regulator or use the sprinkler valve to adjust the water pressure to a proper flow and pressure amount.
Water in the early morning hours. Wind is minimal proving better opportunity for water to land on the target than if it is windy. Further avoiding watering in the daylight hours. This will avoid exposing the air born water droplets to the heat and sun. This would cause excess evaporation. This is more important in humid regions; but try to water closer to sun-up so the surface does not have prolonged moisture all through the night but rather dries sooner when the sun comes up. Minimizing prolonged surface moisture will reduce fugal disease. Also stretch the time between watering days by trying to water fewer days per week rather than watering every day. This will force the development of deep root zones. By developing deep root zones and then allowing the Turfgrass to rely on water stored in it’s roots, both stretches the roots to grow and allows the thatch layer to dry thus reducing disease potential.
If you have established good root depth on your turf, you can use the water restrictions feature in SprinklerTimes.com to stretch your watering days.
Air: Air is a basic element of life. Some plant species need more of it than others. Grass tends to like ample amounts of air. An environment which limits air from over watering or compacted soils will favor other plant types (weeds) which are comfortable with less air. Again, avoid over watering to create the environment that favors the proper amount of air for turfgrass. This provides the competitive edge for turfgrass. Mow the grass in the colder seasons a bit shorter to allow better airflow through the moist season.
Soil Aeration: Aeration is also very helpful to create better airflow to the root systems and allow the soil to breath. Again, top dressing with organic compost after aeration can have long term effects to open the soil, increase worm and microbial activity and stimulate a live and loose soil. My advice is to aerate in the early spring and forgo the fall aeration. Not withstanding adding topdressing compost to the core holes, I believe a fall aeration is somewhat nullified as the soil becomes saturated in the winter time and meshes back together.
Dethatching: Dethatching will also strengthen the turfgrass. It will open the build up of excessive thatch which may have developed over the years or have been accelerated from poor cultural practices and over watering. The dethatching process is a hard pruning of the grass plant and will redirect the plant growth in a healthier direction. It also opens the plant thatch for improved airflow and this improved turfgrass health. The thatching process is very invasive and temporarily damaging. Initially it creates an unsightly appearance, but with proper practices, vast improvements will soon be the result. Recall from the first paragraph, “turfgrass responds rapidly and decisively to the cultural conditions imposed.”
Mowing: Mowing heights can vary depending upon the desired appearance. To determine mowing height, set the mower on a surface or the side of a curb and measure the bottom of the blade to the floor. I recommend mowing as short as possible which means for most turf about 2”. That may be a little too short for some taste. But it adds airflow to the soil. It is recommended to leave it a little longer in the hot season to save moisture in the plant and provide more soil shade. Keep lawnmower blades sharp. Sharpen the lawnmower blade with a file or a grinder, but always use EYE protection! Sharpened mower blades should last about a year for a normal home with 2,000sf of grass. That means you can sharpen each spring. REMOVE the blade to sharpen it. Balance the blade after sharpening it by placing it on a pivot to observe the balance of the blade. If one side is heavier than the other, remove metal from the heavy side as you sharpen until the blade is balanced. Remove the sparkplug wire on gas powered machines and unplug the electric power cord on electric mowers anytime you address the lawn mower blade of a power mower. These are like guns, they are not supposed to be loaded but yet 1,000s of people get maimed each year.
In the SF Bay area we mow every week, mid March through October. We grass cycle, meaning we use specially adapted lawnmower blades that cut the grass into smaller pieces and we leave the chopped cuttings on the grass. After all, what is in the grass clipping but 99% water and nitrogen. Those are the 2 things we continue to apply, so why take it off.
However, that being said, when we mow in the winter, November to March, we do collect the grass as it may be too wet and will tend to make a mess, create clumps, and inhibit good air flow. During these winter mowing cycles, the soil temperature is much lower and therefore the growth rate of grass slows considerably so we mow on a 10 to 14 day frequency.
Food: Food is not as important as water and air, but it is important. The grass can get most of its food from a healthy soil. However like most life forms, a steady regimented diet of proper nutrition will result in the best health. In my experience, most of the soils are not exactly perfect for sustaining turfgrass. I believe a regular diet of fertilizer is required to sustain a healthy turf. The three (3) big numbers on the bag represent Nitrogen, Phosphorus, and Potassium in that (Alphabetical) order. In a good balanced lawn food the numbers should be anywhere in the range of 20-10-5, respectively. Anything within 30% of these numbers will work fine. I personally do not believe in adding chemicals, such as weed killers or weed and feed to the fertilizer. My suggestion is, “If you want to feed, then feed. If you want to kill weeds then kill weeds.” That way it is cheaper and target specific.
Feed on a very regimented schedule. Fertilizes have a variety of release speeds. Some slow release, some quick release. Follow the recommendations on the label regarding frequency of fertilizing and amount of fertilizer to apply. Do some measurements to get the correct pounds to the correct square feet of your turfgrass. Again, follow the manufactures recommendations. The manufactures know this is a highly repeat business model for them. They have put a lot of research into keeping you, the consumer, happy with cost effective results so they can have a competitive product that you will come back to. Follow their recommendation as published on the bag! Besides being the smart thing to do, it is the law.
If you are in a climate which averages above freezing through the winter, and you wish to keep the grass green through the cooler soil temperatures, be sure to feed the grass going into the winter. If you lose the food supply within the grass plants when the soil temperature is low, the metabolism will slow to the extent it will be difficult to regain uptake until the soil warms again in the spring. If you keep food in the plant, it will sustain the metabolism with a green vigor in spite of cooler temperatures down in the 30’s. The plants will still not grow very fast, but they will have a green color.
Competitive Factors: As with any other natural life form, the concept of “survival of the fittest” is applicable for turfgrass. In most cases the conditions which most favor turfgrasses are not so favorable for many of the other plant types. And conversely, creating conditions favorable to other plant types is not as suited for turfgrass. The major factor is the amount of water applied for creating conditions that are best suited for turfgrass. Under watering will weaken the grass and leave room for drought tolerant weeds while overwatering will also weaken the turfgrass and promote soggy loving weeds. A correct watering regimen will encourage good turfgrass root development and maintain vigorous coverage of the soil. The healthy turfgrass will then grow dense and out-compete weeds for the space. The correct application of water for turfgrass for each different month will help create a condition which both favors vigorous turfgrass and discourages plants wanting more or less water. SprinklerTimes.com can determine all of those correct watering amounts for you to create the best completive edge for your turfgrass. SprinklerTimes.com has two basic types of turfgrass to select from in order to optimize the competitive edge for the type of turfgrass selected.
Environmental Factors: Like competitive factors, the environmental factors of temperature range, shade/sunlight ranges, and traffic will impact how you manage your turfgrass to achieve the best results. In general turfgrasses will thrive in temperatures from 35 degrees to 115 degrees, providing that the watering amounts are matched to the conditions. Sprinklertimes.com will provide the best watering program to meet such demands. Turfgrasses need ample sunlight to fulfill the photosynthesis process they require. Some grasses will tolerate less sunlight than others, but there are no conventional turfgrasses that tolerate less than 25% sunlight. With respect to traffic, due to the herbaceous nature, turfgrass can tolerate moderate amounts of traffic for short periods of time. Repeated traffic over the exact same area such as a trail will severely damage the grass and the soil media as well. A sports field for example typically has two things going for it which aid greatly to its sustainability. This is that the sports activities, while intense, is indeed distributed among many parts of the field. Secondly sports fields typically have time between events to repair itself or recover from damages.
The major defense to these environmental factors is to recognize the limitations of turfgrass overall. With that in mind, this is where a more careful selection of turf species is important. There are hundreds of varieties of turfgrass species and cultivars. Know the environmental factors and select a seed blend with has the greatest tolerance to that condition. If you are expecting heavy traffic, select a grass type best suited for that (fescue), or if you have more shade than most grasses will thrive with, then consider a grass type that is better suited for more shade (Red Fescue). But again, even these special purpose grass types will have a blend of seed cultivars blended together in the seed bag or box you buy. If you buy a blue grass seed, you will typically get 6 to 10 varieties of Blue Grass seed mix. Each of these sub species will have its own advantage and environmental preference. The seed count will be plenty to allow for each type of seed to grow in all the planted areas. The benefit to having this blend is that the seed will self-select which ones of the sub-species prefer the conditions in each micro location. The seed variety which survives best in the conditions will best populate that area of the planting, while another area may have an ever so slight difference, and a different sub variety will occupy that location.
For more information about weed control in turfgrass see the tips section for “Weed control for home lawns and gardens”.