Lawn Fertilization

Ask anyone who really knows lawns and they will tell you that the three most important parts of proper lawn maintenance is sunlight, proper watering and the right fertilizer. 

Your lawn needs a balanced fertilizer with nitrogen, phosphorous, and potassium to keep it healthy and strong. Most soils have some of these elements present, but usually they become depleted over the years. Turf is a very hungry plant during its major growing seasons.

Proper fertilizing with balanced applications throughout the growing season promotes thick, dense grass that can resist disease and weed invasions. Applying too much of any one of the basic elements can cause erratic results. For example, an over abundance of nitrogen will cause rapid growth of the grass plants that the roots can't adequately handle; the blades become long and spindly. Balance is the key. As of yet, there is no magic pill for the perfect lawn. Family Tree specializes in understanding your lawn care needs and will develop a program that best suits your lawn

Ideally, you should do a soil test before applying any fertilizer. Some areas have already high levels of phosphorous in the soil. In that case, additional phosphorus is not needed and could cause problems.

Some of the benefits of a properly fertilized lawn include:

Grass that receives appropriate levels of fertilizer — not too little and not too much — produces a dense root and shoot system capable of filtering out impurities or other components that might be found in runoff.

Turfgrasses require 16 chemical elements for growth and development. These elements can be divided into two main groups based on where they are obtained by turf plants. The first group, carbon (C), hydrogen (H), and oxygen (O), is obtained from atmospheric carbon dioxide and water. These elements comprise most of the turfgrass plant.

The second group is minerals taken from the soil or fertilizer applications. This group can further be divided into three sub-groups based on the quantities used by turf plants.

The macronutrients nitrogen (N), phosphorus (P), and potassium (K) are used in relatively large quantities by turfgrasses. The secondary nutrients, sulfur (S), calcium (Ca), and magnesium (Mg), are used in somewhat smaller amounts, and the micronutrients iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo), boron (B), and chlorine (Cl) are used in the smallest amounts.

Of these mineral elements, nitrogen, potassium, phosphorus, sulfur, and iron are most commonly applied in supplemental form to the lawn.

Fertilizer selection

Fertilizer analysis is the percentage, by weight, of nitrogen (N), available phosphoric acid or phosphate (P2O5), and water-soluble potash (K2O) and is represented by the three numbers on fertilizer packages. For example, if you purchase a 50-pound bag of fertilizer with the three numbers being 18-6-12, that means you are purchasing nine pounds of nitrogen, three pounds of available phosphoric acid, and six pounds of water-soluble potash.

Other mineral nutrients can be present in the fertilizer and are normally shown on the back of the package. Sulfur, iron, calcium, and magnesium are possible examples of mineral nutrients that may be present. Fertilizer ratio is the proportion of nitrogen, available phosphoric acid, and water-soluble potash in the package. For instance, in the previous example, there are three parts of nitrogen to one part of phosphoric acid to two parts of potash. This fertilizer’s ratio is 3:1:2. In a fertilizer with an analysis of 10-10-10, the ratio is 1:1:1, and in a fertilizer with an analysis of 20-5-10, the ratio is 4:1:2. This information is useful because it is often recommended that fertilizers with a 3:1:2, 4:1:2, or 5:1:2 ratio be used as general-purpose turf fertilizers.


Nitrogen is the most important element in turfgrass culture because it is present in larger percentages than other minerals in turf tissues. This large quantity of nitrogen is used by turf for the formation of chlorophyll, a substance necessary for photosynthesis. Nitrogen also comprises portions of plant proteins, amino acids, enzymes, and vitamins. Obviously nitrogen is important for turf development and health. Nitrogen is absorbed by turf plants primarily in the nitrate (NO3-) form, although the ammonium form (NH4+) can also be taken in by the plants.

Nitrogen fertilization is also important for turfgrasses because it elicits the strongest growth response of any mineral element. Nitrogen mineral fertilization is often used to enhance green color and increase or maintain high density, both of which improve turf appearance. Response to nitrogen fertilization can be quick; under

Cool season nutrients

It is recommended that mineral nutrients be supplied to take advantage of periods of active turf growth. For cool-season turfgrasses, mineral nutrients should be supplied to correspond to the active periods of growth in the spring and autumn. In fact, some turf managers believe that one-half or more of the annual fertilizer application should be made after September 1 each year to take advantage of the active growth that occurs in cool periods. Fertilizing in autumn helps turf plants recover from summer and store mineral nutrients for use during the following season’s growth. Finally, fertilizing at the time of cultivation (such as aerification or dethatching) can help the turf recover more readily.

Warm season nutrients

Warm-season turfgrasses (such as zoysiagrass, bermudagrass, and buffalograss) grow actively when temperatures are warmer, usually from mid-spring through mid-fall depending on latitude. Warm-season grasses usually are fertilized at least once per year in the spring at the initiation of growth. Successive applications can be made monthly during active growth.

Fertilizer application

Turfgrass fertility programs often revolve around the quantity and timing of nitrogen applications. Nitrogen is used by turf plants in large quantities, and because it is rapidly tied up, it should be applied to most turfs one to four times per year. Most turf fertility recommendations will indicate the pounds of actual nitrogen to be applied per 1,000 square feet of turf per year.


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