Photo credit: Nancy Knauss
How do you define a healthy lawn? Is it a uniform weed-free swath of tightly clipped emerald blades of grass? Or, does a mix of turf and weeds allowing a pack of kids and dogs playing Frisbee, without a lick of chemicals, fit the bill best for you? For most it’s somewhere in between.
Lawns absorb rainfall and minimize runoff, provide unmatched surface for play and foot traffic and the improve the appearance of a home, setting off beds and borders. Regardless of whether you employ chemical treatments to keep your lawn weed free or eschew them, believing that a healthy lawn is chemical free, there are ways of boosting the health of turfgrass in your lawn, allowing it to outcompete common weeds and resist pests and disease.
Begin with a soil test. The best way to determine what your lawn needs is to examine the soil where it grows. Soil test kits, along with detailed instructions can be obtained at your local Penn State county extension office. Further information about soil tests can be found on Penn State Extension’s websit.
Soil pH will be part of the test report; it should be between 6.0 and 7.5. Soils having a lower pH indicate more acidity, therefore an application of lime may be recommended.
The single practice that does more to improve and maintain a lawn is proper fertilization. Complete fertilizers contain nitrogen (N) for good green color, phosphorus or phosphate (P) for root development and growth, and potassium or potash (K) for tolerance to drought stress. Fertilizer ratios, written as NPK, are required on packaging and indicate the relationship among the percentages of nutrients. Fertilizers graded 16-8-8 and 10-5-5 both have the same ratios of nitrogen, phosphorous and potassium (2-1-1).
Soil tests provide specific data on phosphorus and potassium. Nitrogen levels are not reported on soil tests, because nitrogen levels can change quickly. However, the soil test results will include a recommendation for an amount of actual nitrogen that needs to be supplied annually to ensure optimum turf quality. If no phosphorus or potassium is recommended, and you have not fertilized your lawn by mid-May, an application of one pound of nitrogen per thousand square feet is a good idea. More is not better. Look for fertilizers that contain some slow-release nitrogen. Over fertilization can leave your lawn susceptible to more disease problems, and rainwater runoff laden with excess fertilizer creates dangerous algae blooms in local waterways. Make a second application in late summer or early fall.
One quarter inch of well-aged compost can be broadcast on lawns in the spring to provide small amounts nitrogen and beneficial micronutrients. Incorporation of compost is best accomplished along with the process of aeration described below.
Mowing is the most important factor in lawn appearance and longevity. Maintaining a lawn height close to three inches helps stimulate root growth and shade out unwanted weeds. Sharp, properly adjusted mower blades provide a clean, even cut that heals quickly, and appears well-groomed. No more than one third of the grass blade should be removed at any given mowing. This means that weekly mowing is often not enough during peak spring growth and rainy periods. Using a mulching mower reduces the labor of bagging. Mulched grass clippings return nitrogen and other essential nutrients to the soil and decompose rapidly, so they do not contribute to thatch. Thatch is made up of dead leaves, stems and roots that are naturally shed and accumulate between the crowns of the grass and the soil surface. Some grasses accumulate thatch much faster than others, and over fertilization and over watering both encourage excessive growth, which promotes thatch buildup. Liming, fertilizing, and mechanical dethatching every two to three years will result in much less debris and damage.
How frequently to water your lawn depends on the type of grass, soil and weather conditions. It is a good idea to let the condition of the grass determine when to irrigate. The optimum time to apply water to lawns is just as plants begin to wilt. Once root zone is thoroughly moistened, additional water only serves to encourage shallow roots and traffic damage and attracts disease and insects. Frequent, shallow watering tends to keep the root zone saturated too much of the time. Watering deeply, only when needed, promotes healthy and vigorous turf.
Aeration is the best way to alleviate soil compaction in established lawns. Aerators remove 3 to 4-inch plugs of soil from the turf, allowing oxygen, moisture and nutrients directly into the root area. Solid spikers are not aerators; they actually increase soil compaction. A good rule of thumb is to aerate every three years. Spring and fall are the best times to aerate.
The best time to plant a new lawn is in the fall, but overseeding to fill in bare patches, or to thicken and improve established turf can also be successful in spring. Read the label before purchasing seed. High quality seed is always the best choice. Packaging is required by law to list the types and percentages of each grass seed species, other crop seed (the lower the better) and weed seed (should be less than 0.5%), as well as germination rates.
Should you choose to apply herbicide to control weeds in your lawn, be sure to treat them at the earliest signs of growth, and always follow the recommendations on the label.
Many homeowners are weighing the time, expense and chemical usage required to maintain a perfect lawn and are converting part or all of their lawn to lower maintenance grasses and groundcovers such as clover.