Lawn Fertilization Psychology

As research and technology seem to have improved all aspects of our modern life, one may presume that lawn care has been exacted to a precise science with new and improved grass varieties, time-release fertilizer, aeration and other proven management practices. Yet, in reality, many homeowners still struggle with lawn care. Make no mistake: beautiful lawns are not achieved by accident, nor are they the blindly benevolent result of good soil. Rather, they are the result of timely work, an attitude pursuant to a quality lawn and the knowledge to achieve those goals. With poor management, even "good soil" will result in an inferior turf. While most people have limited time to work on their yards, it is important to apply that limited time when it can do the most good. One of the requisites of a good lawn is timely fertilization, but the proper timing can seem contrary to seasonal urges to work in the yard. In fact, the optimal time to fertilize comes when one’s attitude about their lawn probably reaches rock bottom. It is possible for soil to be deficient in several nutrients-take a soil test to be sure—but, nitrogen is by far the nutrient most commonly deficient, and recommendations for nitrogen application to lawns are made regardless of the soil’s capacity to supply nitrogen. Instead, a schedule of fertilizations is recommended based on the level of maintenance desired. This discussion will cover some of the proper fertilizer management practices and the psychology that one might deal with in practicing them.

The normal lawn in this area is a mixture of cool season grasses (they grow best during the cooler temperatures of spring and fall) such as fescue, bluegrass, and ryegrass. These grasses begin to green up in the spring in concert with trees, shrubs and many perennial garden plants. Homeowners often are caught up in the spirit of the season of greening, and, wanting to be dutiful toward lawn care, think they need to assist their grass by fertilizing it. Grass quickly responds with a lush appearance and a deep green color. So, homeowners feel justified and rewarded to have applied fertilizer. The problem with this is that spring is not the best time to fertilize a lawn, and it may be detrimental to the long-term health of the lawn.

As spring fertilization stimulates top growth which causes the lush appearance, the grass is concurrently discouraged from storing food reserves for the hard times to come-summer. It is analogous to giving candy to a child. It is quickly gobbled up and sparks a spurt of energy, but nothing is provided for growth in the long run. The likelihood of harmful stimulation is dependent upon how late the fertilizer is applied and how quickly the fertilizer is available. Fertilizers that contain 50 to 70 percent slow release nitrogen (read the fertilizer label) can be applied into early May when no more than one lb of nitrogen per 1000 square feet is applied. Quick release fertilizers should not be applied after May 1, but can be applied through March and early April.

In addition to discouraging storage of food reserves, the lush top growth also provides an environment conducive for diseases to take hold and sweep through a yard. Therefore, when summer comes, the spring-only fertilized lawns are often more susceptible to the summer stresses of disease and moisture stress. Consequently, lawns that appeared so great in April and May often suffer substantial losses of turf coverage during July and August. The degree of decline is dependent on the actual species or variety of grass in the lawn, as some are more resistant to disease or moisture stresses that are exacerbated by stimulating the grass’ growth at the wrong time.

Sometimes the full extent of the damage isn’t recognized until October. This is because weedy grasses (crabgrass and bermudagrass) may fill in the dead areas providing "green" cover, but these grasses die or go dormant with the first frost. Coarse-textured fescue may also survive-giving the appearance of green patches of coarse bladed grass in dead brown grass-but it is typically considered a poor lawn grass. Changes in lawn appearance in October can be indicative of whether proper lawn care is being practiced. Properly fertilized lawns tend to improve in appearance, while the opposite occurs for improperly fertilized lawns. Thus, there occurs another quirk of lawn care psychology. The euphoria of spring bottoms out to a summer depression. Through a failing of basic lawn care knowledge, dutiful work and good intentions are met with undesirable results. Subsequently, enthusiasm fades into indifference. On the other hand, sometimes there is a scapegoat, and often it is the soil.

"There has to be something wrong with my soil. My grass looked so great in the spring and then it all died."

Likely, though, the soil had little to do with the decline of the lawn. The irony of lawn care psychology is that at the end of August when the appearance of one’s lawn and one’s sentiments about it hit a low, this is the best time to fertilize or renovate a lawn. By this time, grasses have endured the summer stresses and the coming cool fall temperatures will provide an opportunity for recovery. Fertilizing at this time encourages the plant’s recovery by providing nutrients when the plant really needs them to build food reserves going into the winter. In addition, the growth habit of the plant is somewhat different than in the spring. As air temperatures cool, the cooling of the soil lags behind. This autumn temperature profile reduces the grass’ above ground growth but increases growth below ground, primarily in roots and tillers. With increased tillers, lawns fill in dead spots and thicken in general. Alternatively, in the spring, cool soil temperatures and warm air temperatures encourage top growth that is only promoted by fertilizer-to the detriment of the long-term health of the grass and an increase in the time spent mowing. While it doesn’t have to be done precisely at this time, Labor Day weekend is a good time to make the first fall fertilization to lawns, as the cool temperatures are soon to come.

Ideal fall fertilization also includes a late fall (November) application. Again, this may seem to be contrary to people’s attitudes in regard to their lawn care. By this time, most people will be considering a final fall mowing, and fertilizing at this time may seem rather odd. Although the air temperatures will have cooled substantially by this time, soil temperatures will remain warm enough for some-primarily root and tiller-grass growth. This late fall fertilization helps winterize the grass and sets the stage for the grass to make a quick start in the spring. Depending on the onset of true winter weather, such a late fall fertilization may result in an additional mowing. However, the payback is that the grass will have a dark green color going into winter that returns early in the spring.

So far this discussion has covered fertilization for basic maintenance of lawns. It might be argued that high maintenance of lawns requires another mindset-a ratcheting up of what one is willing to do. Additional fertilizations will be required, but other complementary practices are also necessary. Just as a dense green yard is attractive to humans, it also becomes attractive to insects and so more predisposes the grass to disease. Thus, preventative measures in the form of insecticide and fungicide applications become more important. With the proper protective measures taken, additional fertilizations (totaling 3.5 to 5.0 lbs of nitrogen per 1,000 sq.ft. per year) can be made for high maintenance care. These applications will ensure a lush green lawn the entire growing season. Of course, this assumes that irrigation will be provided to avoid summer dormancy during the dry periods of July and August.

While good soil was previously discounted as a primary reason for a beautiful lawn, it can be helpful. Some soils have properties that inflict stress on grass during different times of the year. These include poor drainage, excessive slope or high clay content that restrict water intake, poor aeration, and high acidity level. Indeed, the beautiful turf one sees on professional athletic fields almost certainly is the result of soil that has been trucked in to make turf management easier.

Formerly, most lawns were only of the cool season type; that is, they grow best during the cool months of April to May and September to October. Now, some homeowners are switching to zoysia or bermudagrass lawns. These warm-season grasses grow best during the warm months of June through August. Subsequently, timing fertilizations for them is altogether different than for the commonly grown cool-season grasses. Recommended fertilization times are late May and mid-July or once a month for high maintenance care; it is at these times that stimulation of the grass is desired. Again, a new psychology is necessary for these grasses. While quite hardy for enduring summer stresses, they are dormant for more months of the year than cool-season grasses, and during dormancy they have a tan or brown color. Among the trade-offs is hardiness in the face of summer stresses versus green color for a much shorter time during the year.

While it is true that modern lawn care can be more sophisticated than in the past, for homeowners there is and always will be the human element. As long as basic lawn care principles are misunderstood, there will always be the potential for "human error." Such misunderstandings can be corrected through education on fertilizer types and timing of applications. At times it is more important to ignore our seasonal urges and follow responsible soil management practices. Once proper lawn care is understood, there is the question: "What am I willing to commit in terms of time and resources?" For lawns, the higher the goal, the greater is the commitment.

Brad Fresenburg, Extension/Research Associate, Turfgrass Research Center, UMC (573)442-4893
John Stecker, Soil Testing Laboratory, UMC (573)882-0623