A mature, unmowed grass plant is composed of leaves, roots, stems, and a seed head. Some grass species do not have all the structures shown, and mowed grasses typically lack flower stems and seed heads. Soil conditions, moisture, aeration, drainage, nutrients, and sunlight all play a role in the health and vitality of different varieties of turfgrasses.
Differences exist in growth habits, color, texture, growth cycle, optimum mowing height, water requirements, and needed nutrients as well as susceptibility to pests, weeds, and diseases. Although there are many varieties of turf-type grasses, all fall into one of two classifications: cool-season grasses, which, as the name suggests, grow well in the cooler months, and warm-season grasses, which turn brown whencooler temperatures arrive. Maryland is located in a transition zone. Both cool-season and warmseason turfgrasses can grow; but Maryland’s climate does not favor growing either group of grasses throughout the entire year.
Scientists have mapped over 70,000 different soil types. Understanding the soil type you have is an important step in building a healthy lawn. All soils are comprises of different layers called horizons. Soil fertility and its management is a complex process that involves numerous factors above and beyond fertilizer applications. The interactions between soil texture and structure, organic matter content, water retention, cation exchange capacity, pH, and nutrients determine the appropriate nutrient applications and how plants will respond after nutrients have been applied.
Having a realistic expectation of what your lawn will look like throughout the year is important. Different grasses grow at different times and rates throughout the year.
Cool-season grasses grow best in cool weather. These grasses turn green in spring and stay green longer in the fall months because they prefer cooler temperatures. Common kinds include bluegrass, fine fescue, tall fescue, red (creeping) fescue, and perennial ryegrass. Shoots of coolseason grasses grow actively in the spring, representing 60 percent of all top growth. This top growth slows in the fall, but root growth continues. Because Maryland weather is variable, these grasses may show growth at any time of the year. Summer dormancy is a survival response to heat and drought and presents itself as off-color or browning.
The most popular warm-season grasses found in Maryland are zoysiagrass and bermudagrass. These grasses grow best in the summer. They turn brown or straw colored when cooler temperatures arrive in the fall, usually at the first frost. These sun-loving plants also green up later in the spring—typically June 1—as compared to cool-season grasses whose season lasts from late spring until early fall.
For turf-type tall fescue, mowing below 3 inches has negative impacts upon turf performance, health, and appearance. Low and infrequent mowing are perhaps the major causes of lawn deterioration. Mowing low forces the plant to put more energy into top growth. The result is shallow and less-dense roots, which allow more weeds to emerge. When mowing, never remove more than 1/3 of the leaf surface at any time. For example, if the desired mowing height is 2.0 inches, do not allow turf to grow higher than 3.0 inches before mowing. By mowing to a height of 3.0 to 3.5 inches, broadleaf weeds can be reduced by 50 to 80 percent compared to turf mowed at a 2.0- inch height. Taller turf results in roots that are healthier and turf that is cooler. Finally, taller turf stays greener in the summer. It is best to maintain the mowing heights shown in Table 4. Mow as needed and return clippings to the lawn, but avoid mowing when turf is under heat and drought stress.
Grass Clipping Management
In a field plot study (Starr and DeRoo, 1981), impacts of clipping management were examined. Test plots with returned clippings had more vigorous growth. The average daily rate of growth was 60 percent greater for the plots with clippings returned. Soil nitrogen in the first 10 centimeters was greater for the plots with clippings returned. Another study (Kopp and Guillard, 2002) found that returning clippings to the lawn improved the growth and quality of turfgrass and reduced the need for nitrogen fertilization by as much as 50 percent.
Material in this page adapted from Maryland Professional Lawn Care Manual (2013)