Know The Fertlizer Numbers

Source(s): Clint Waltz, Extension Turfgrass Specialist, The University of Georgia

Most folks have heard of 10-10-10, but they may not know what the numbers stand for. So what are the numbers?

All plants require nutrients to grow and develop properly. Various nutrients affect plants differently and are needed in varying amounts.

Essential nutrients are just that: essential. Plants have to have them to sustain the vigor they need to resist environmental stresses, weeds, diseases, insects and other pests.

The 16 essential nutrients are broken into two categories, primary (nitrogen, phosphorus and potassium) and secondary (calcium, magnesium, sulfur, iron and others).

The primary nutrients get the most attention because they’re required in the greatest amounts. Fertilizers are sold based on their amounts.

The numbers

On a fertilizer bag, the numbers refer to the percentage of actual nitrogen (N), phosphate (P2O5) and potash (K2O). So 10 percent of the weight of a bag of 10-10-10 is nitrogen, 10 percent is phosphate and 10 percent is potash.

It’s easy to figure the actual weight of nitrogen. The percentage is listed on the bag. In a 50-pound bag of 10-10-10, the nitrogen would weigh 5 pounds (0.10 times 50).

It’s not as simple, though, for phosphorus (P) and potassium (K). To find the amount of phosphorus, multiply the phosphate number by 0.44. Get the potassium amount by multiplying the potash weight by 0.83.

How it adds up

So that 50-pound bag of 10-10-10 has 5 pounds of phosphate times 0.44, or 2.2 pounds of phosphorus. It has 5 pounds of potash times 0.83, or 4.15 pounds of potassium. With the 5 pounds of nitrogen, then, it has 11.35 pounds of primary nutrients.

Using the same formula, a 50-pound bag of 16-4-8 would have 8 pounds of nitrogen, 0.88 pounds of phosphorus and 3.32 pounds of potassium. That’s 12.2 pounds of primary nutrients.

So what’s the rest of the weight in the bag? Some of it may be secondary nutrients. The rest is filler material to make it easier to apply.

A fertilizer bag containing all three nutrients is considered a “complete” fertilizer. A product with any nutrient missing is called “incomplete.”

Center Publication Number: 146

Fertilizer Calculations for Attractive, Healthy Lawns

Source(s): Clint Waltz, Extension Turfgrass Specialist, The University of Georgia

Applying the correct amount and type of fertilizer is essential in order to produce an attractive, healthy lawn.

Lawn fertilizer recommendations are generally made in pounds per 1,000 square feet of lawn area.

The square footage of a lawn area can be easily calculated. Simply walk off the length and then the width of the yard, taking 3-foot steps. Multiply the total number of steps in each dimension by 3. Then multiply the length times the width of the yard. Remember to deduct areas such as driveways and home area.

Lawn Fertilizer Calculations

Fertilizer Calculations

If a recommendation requires a complete fertilizer, any complete fertilizer of the same ratio can be used. Example:

  • 10-10-10 (1-1-1 ratio) can be used for 8-8-8.
  • 5-10-15 (1-2-3 ratio) can be used for 7-14-21.

A common recommendation for turfgrasses is to apply 1 pound of nitrogen (N) per 1,000 square feet. To determine how many pounds of fertilizer it would take to supply 1 pound of N, divide the percent nitrogen of the fertilizer into 100. (Note: This is only true when working on a 1,000 square foot basis.)

Examples: How many pounds of (1) 10-10-10; (2) 12-4-8; (3) 5-10-15; and (4) 16-4-8 are needed to apply 1 pound of N per 1,000 square feet.




10 pounds of 10-10-10





8.3 pounds of 12-4-8





20 pounds of 5-10-15





6.3 pounds of 16-4-8


In cases where you are substituting complete fertilizers of different ratios, the application rate should be based on the amount of that fertilizer needed to supply the recommended amount of nitrogen. Thus, all of the above fertilizers would supply 1 pound of nitrogen at those calculated rates.

This same calculation can be applied to other fertilizer materials.



Ammonium nitrate (33% N)



3 lbs. of ammonium nitrate will supply 1 lb. N



20% superphosphate (P2O5)



5 lbs. of superphosphate will supply 1 lb. P2O5.


These rates can be converted to a per-acre basis by multiplying by 43.5. Per-acre rates can likewise be converted to per-1,000 square feet by dividing by 43.5.

  • 10 pounds of 10-10-10 per 1,000 square feet equals 10 x 43.5 = 435 pounds per acre.
  • 435 pounds of 10-10-10 per acre equals 435 divided by 43.5 = 10 pounds per 1,000 square feet.

Resource(s): Lawns in Georgia

Center Publication Number: 138

Manage Phosphorus Carefully in Lawns

Source(s): Clint Waltz, Extension Turfgrass Specialist, The University of Georgia

From time to time, concerned citizens try to pressure lawmakers to eliminate phosphorus from lawn fertilizers. They mean well.They’re looking out for our water resources.

Unfortunately, they don’t understand how phosphorus enters aquatic systems or its role in plants and its behavior in soil systems. They fail to understand, too, that phosphorus is an essential nutrient. It’s a “must have” for plants to grow.

Soil phosphorus levels aren’t static, either. Low levels of phosphorus have to be applied each year to maintain proper soil nutritional balances.

Besides, applying phosphorus carefully while using “Best Management Practices” can greatly ease the environmental concerns.

Especially here

You have to apply phosphorus in the Southeast. Because it’s hotter and wetter here with a longer growing season than in most of the country, Southeastern soils have less phosphorus than in other regions.

And plants can’t do without it. It’s the second-most essential element, behind nitrogen, for plants’ growth. And plant roots readily extract it from the soil.

Phosphorus is in such high demand because plants use it in the metabolic processes of energy transfer. So it has to be added back to the soil for plants to keep growing well.

Too much of a good thing

In excess amounts, though, phosphorus can harm the environment. That’s especially true when it runs off into streams, ponds or lakes.

Aquatic plant life must have a balance of nutrients. But high phosphorus levels stimulate excessive growth of aquatic plants and algae.

The problem is that when this excessive plant life dies and decays, the process takes oxygen from the water. And when oxygen levels drop, fish and other aquatic animals die.

Pollution solution

It’s important to remember that the way most phosphorus reaches water bodies is in soil erosion. Nonpoint-source pollution of water bodies can be greatly reduced by managing soil erosion.

Of the phosphorus lost to lakes and streams through soil erosion, 75 percent to 90 percent is fixed to soil and organic matter. This fixed phosphorus has been shown to contribute to the growth of algae.

Turf grasses, which need phosphorus to grow well, can help the environment. Turf will greatly slow the flow of water across the soil surface and effectively reduce soil erosion.

A cover of turf will allow water to gradually infiltrate into soil, too. Once soluble phosphorus enters the soil, it’s quickly bound to soil solids and organic matter and becomes relatively harmless.


Nonpoint-source pollution from phosphorus can best be controlled by using best management practices.

Soil testing is one BMP that can help. But you have to use proper soil-sampling techniques. Your county University of Georgia Extension office can help you with this.

In general, it’s best to apply phosphorus according to soil test results. There are exceptions. A fertilizer with low rates of phosphorus may help a turf grass that’s stressed by cold or wet soil, for instance, or when root-rotting diseases have damaged the roots.

A second BMP is the use of fertilizers with low phosphorus levels. Many modern lawn fertilizers have been engineered to meet the needs of most turf grasses.

It’s not uncommon to see products with analyses like 29-3-4 or 27-4-4, in which the content is around 1 part phosphorus for every 8 to 11 parts nitrogen. Zero-analysis phosphorus fertilizers are also available.

A third BMP to keep phosphorus out of water resources is to not apply fertilizer to hard surfaces such as driveways, sidewalks and streets.

Remember, when water-soluble phosphorus contacts soil and organic matter, it quickly becomes immobile in the soil. So just sweeping or power blowing fertilizer that lands on hard surfaces can greatly reduce the amount of phosphorus moving through storm-water systems into reservoirs.

Resource(s): Lawns in Georgia
Center Publication Number: 152

Off-Season Sodding

Source(s): Clint Waltz, Extension Turfgrass Specialist, The University of Georgia

Dormant transplanting of trees and ornamentals in the Southeastern United States is a common practice; likewise, warm-season turfgrass sod can be successfully established during dormancy.

Research has shown that bermudagrass root growth is significantly reduced when average soil temperatures drop below 60 degrees F. In the Atlanta area, this would generally occur the first of November. Generally temperatures would not reach 60 degrees F. until the latter part of April. These observations generally agree with the normal dormant period of most warm-season turfgrasses and are commonly recognized as a risky period for sodding. However, substantial quantities of sod are transplanted during this period of slow growth or dormancy.

Off-season or dormant sodding (October-April) provides the following advantages:

  1. Provides for instant landscape;
  2. Improves the environment by reducing erosion, mud, dust and weeds around buildings;
  3. Increases occupancy rates of newly finished construction projects such as homes and buildings;
  4. Extends the producer’s and landscaper contractor’s production time, thus reducing the peak demand season.

Recommendations for normal sodding also apply to off-season sodding. Rootzone preparation is critical for success. During site preparation and prior to turf establishment is the best time to take a soil sample to determine pH and nutrient needs. Modification of soil pH is most beneficial when lime (used to raise pH) or sulfur (used to lower pH) can be incorporated into the soil. Loosening the soil to a depth of 6 inches by tilling is usually ideal for turfgrass establishment.

Also, corrections of soil nutrients deficiencies like phosphorus(P) and potassium(K) are more easily made prior to establishment. While all essential nutrients are required for turfgrass growth, there is inconsistent information on P and K needs during establishment and winter. Some studies report decreased winterkill and disease occurrence with the addition of P and K, while other researchers have reported no differences in cold hardiness or pathogen resistance due to increased rates of P and K.

Next, the tilled soil should be leveled, smoothed and moistened. The soil should be lightly watered, but not saturated. Ruts from foot traffic or equipment can occur when soils are excessively wet and are more difficult to repair after the sod is laid. To prevent drying and potential cold injury of roots, sod should be installed within 48 hours after harvest. Also, the radiant heat from the earth may offer some protection from cold injury when compared to turf exposed to the elements when left on a pallet. Sod should be laid tight and rolled to minimize creases. If creases are apparent once the turfgrass has been laid, the sod should be topdressed to fill low spots, conserve moisture and potentially retain heat near the soil surface.

The survival of off-season transplanted sod is dependent upon avoiding winter desiccation and low temperature injury. Due to a limited root system, desiccation can be a significant problem. The warm dry winds of late winter and early spring increase the demand for water, but the combination of low soil temperatures and a limited root system will reduce the plant’s ability to obtain water and nutrients. Direct low temperature injury can be a problem because the crowns, stolons and shallow rhizomes may be killed. Unfortunately, newly sodded turf lacks deep rhizomes and the expansive root system necessary to recover from winter stresses.

Research and practical experience has shown that warm-season turfgrasses may be successfully sodded during the off-season (October-April) when the grass is dormant or slowly growing. However, the cooler climates in and north of Atlanta may adversely influence some species. Increased winter injury has been observed on zoysiagrass and centipedegrass compared to bermudagrass sodded late in the year.

Nonetheless, successful transplanting is highly dependent on a healthy sod, which is difficult to determine when the sod is dormant or overseeded. Overseeding sod with ryegrass may reduce bermudagrass vigor and quality. While overseeded turf may look appealing during the winter months, during the spring the more heat-tolerant perennial ryegrasses can compete with the warm-season turf for water, nutrients and light, resulting in a poor transition and delayed green-up of the warm-season species. This is more common in ryegrass that has been heavily fertilized in the spring. To assist spring green-up and stimulate turfgrass growth, fertilize with 1.0 to 1.5 pounds of nitrogen per 1000 square feet once night temperatures consistently reach the mid 60s F. Also to further encourage warm-season species growth, the mowing height can be lowered. This practice opens the turfgrass canopy, allowing more sun to the permanent warm-season species while stressing overseeded grass. Resume accepted maintenance practices once conditions are favorable for warm-season turfgrass growth.

In summary, successful sod transplanting depends on proper soil preparation, good soil-to-sod contact, avoiding low temperature injury, and most important, proper water management to prevent desiccation.

Resource(s): Lawns in Georgia

Center Publication Number: 142

Seeding Tall Fescue Lawns

Source(s): Clint Waltz, Extension Turfgrass Specialist, The University of Georgia

Tall fescue (Festuca arundinacea) is a popular cool-season grass species that has a bunching to weakly rhizomatous growth habit. Tall fescue is best adapted to Georgia’s piedmont region and is used for home lawns, general areas and for soil stabilization. In general, the southern boundary for tall fescue growth would be Griffin, although, it can be found in shaded or protected microclimates further south.



Because it can be seeded, tall fescue is very popular with do-it-yourself homeowners. Furthermore, its popularity relates to the genetically dark green color during the spring and fall. The use of tall fescue has increased since the introduction of “turf-type” cultivars in the early 1980’s. The turf-type cultivars have darker green color, finer leaf blades, lower growth habit, greater density, and improved shade tolerance compared to the more traditional ‘Kentucky 31’ (K-31) type tall fescues. Additionally, research has shown that some turf-type cultivars have deep extensive root systems and other genetic characteristics for improved drought tolerance.


September and October are the ideal months to plant tall fescue. Grass seeded earlier is subject to heat stress and diseases, while planting later leaves the plant vulnerable to cold weather. Seeding in December and early spring is generally not recommended because the plant does not have adequate time to develop a deep root system needed to survive Georgia’s hot summers.

During the summer months, it is common for the canopy of tall fescue to thin and become more open. This is a heat-stress survival mechanism that allows the plant to conserve energy until climatic conditions are favorable for growth. However, a thinned and open canopy makes the tall fescue less competitive and more susceptible to summer annual grassy weeds, like crabgrass. Preemergence herbicides are needed to minimize weed pressure, but research has shown that these herbicides pose the least amount of risk to tall fescue that was seeded the previous September and October. Tall fescue seeded in November and then treated with preemergence herbicides the following February had lower turfgrass quality ratings and reduced stand density compared to tall fescue seeded in October.

Soil Preparation

Proper soil preparation is critical for an effective seed establishment. Ridding the lawn of debris, tilling, incorporating lime and fertilizer, and smoothing the surface are all necessary prior to seeding. Add any amendments such as organic matter or topsoil for soil improvement and till thoroughly into the existing soil. After initial preparation is completed and the area is properly leveled, collect a soil sample to obtain soil fertilizer recommendations. Then incorporate the starter fertilizer and lime 3 to 4 inches into the soil before planting. If equipment permits, tilling deeper is always better.


To ensure varietal purity plant seed that is certified and identified by a blue tag. Such seed has been tested and the information on the label is assured by law. In the retail market most tall fescue seed is available as a blend, where several tall fescue cultivars are blended together. Single cultivars are also available but often at a higher price compared to blends. Orchardgrass is a common weed seed contaminate found in tall fescue seed and is easily seen in lawns because of its blue- green color and faster growth rate. Unfortunately, it cannot be selectively controlled with a herbicide.

The ideal seeding rate for tall fescue is 5 pounds per 1,000 square feet. To minimize skips and gaps, it is best to divide the seed into two equal portions and broadcast half in one direction and the remainder at a right angle to the first direction. This procedure is also recommended for fertilizer and granular pesticide applications. The seed can be lightly raked into the upper ¼ inch of soil or pressed into the seedbed with a roller. Applying a straw mulch to retain moisture for improved germination and prevent erosion can be beneficial.


After seeding, keeping the upper 1 to 2 inches of soil moist, not wet, is necessary for uniform germination. This usually means daily watering of about 1/8 to ¼ inch for the first three weeks. As the seedlings develop, irrigate less frequently but wet the soil profile deeper. Under good conditions tall fescue seed will germinate in 5 to 10 days and be ready for its first mowing between 2 and 3 weeks.


Begin mowing at a height of 2 inches and as the seedlings mature, raise the cutting height to the 2 ½ to 3 inch range. Once mature, the lawn can be maintained between 2 to 2 ½ inches, but a height of 3 inches is suggested during the summer months. Use a mower with a sharp blade and mow often enough so no more than 1/3 of the leaf height is removed in a single mowing. Do not mow a grass when it is wet, especially young seedlings.


It is common for tall fescue lawns to thin and need periodic reseeding. Turf thinning is usually caused by environmental stresses, improper turf management like insufficient irrigation, too much nitrogen fertilizer, seeding with more than 5 pounds of seed per 1,000 square feet, mowing too low or too high, and seeding in late fall or spring. Additional problems include pests like crabgrass or white grub infestation, or disease problems like brown patch. Soil related problems like a hard compacted rootzone, and environmental conditions where tree shade and root competition compete for water and nutrients also contribute to canopy loss. All of these factors, however, can be mitigated with proper management.

If the lawn needs reseeding, estimate the percentage of tall fescue loss and multiply that number by the establishment seeding rate of 5 pounds per 1,000 square feet. For example, if 50 percent (0.5) of the stand is lost, reseed with 0.5 x 5 = 2.5 pounds per 1,000 square feet. Spring reseeding is less successful because of the shorter establishment time before summer heat and moisture stress.

Getting the seed in contact with the soil is necessary to assure successful reseeding. First, mow the lawn at a height of 1 to 1.5 inches. Disturb the soil preferably by coring or vertical mowing before and/or after seed distribution. This equipment is often available at rental or garden centers. Reseed thin areas at 2 to 5 pounds per 1,000 square feet. Getting the seed below the existing turfgrass canopy and to the soil surface improves germination. Apply a starter fertilizer at 1 pound of nitrogen per 1,000 square feet at this time. Finally, keep the soil moist as discussed for new lawn establishment.

In summary, successful seeding depends on proper soil preparation, good soil-to-seed contact and, proper water management. This and other fact sheets are available at and


Lawns in Georgia

Center Publication Number: 218

Spring Greenup Problems

Source(s): Clint Waltz, Extension Turfgrass Specialist, The University of Georgia

Warm-season turf grasses such as Bermuda, centipede, zoysia and St. Augustine suffer some common problems with springtime green-up. Here are problems we see most often.


Mowing height is the most common problem as these grasses go from dormancy to active growth. Scalping is more common in zoysia grasses, especially in the denser-growth cultivars like Emerald.

Zoysia grasses don’t tolerate scalping as Bermuda will. As a rule, zoysia will be set back anytime it’s cut low enough that you can see the black mold under the leaf canopy. This is generally below the node of the growing leaves. It can occur at any mowing height from as low as 0.5 inches to more than 3 inches.

Regardless of the grass species and normal mowing height, taking the grass down below the node will set it back. Generally, the higher the mowing height, the more this is a problem.

Ideally, maintain Bermuda grass and centipede between 1 and 2 inches, zoysia from 0.5 to 2 inches and St. Augustine from 2 to 3 inches.

Mowing frequency is just as important as mowing height. If you remove more than one-third of the leaf height at a single mowing, the grass will be stressed.

Fertility requirements differ with each grass. Consult your county University of Georgia Extension Service agent or visit for fertility recommendations.

No matter what the species, though, fertilizing too early in the season, before soils are warm enough to support continual growth, can accelerate green-up but cause detrimental long-term effects.

Fertilizing these grasses in late-winter or early spring can cause them to break dormancy. Then when the inevitable late-season cold snap hits, they’ve used their stored food reserves. They have no energy to withstand environmental extremes. To avoid this, don’t fertilize until the soil reaches 65 degrees.

Thatch, as lawns get older, becomes more problematic, particularly if the turf has been mowed above its recommended height ranges. Increased thatch slows down the turf’s spring transition. It makes it more susceptible to disease, too.

Water — either too much or too little or even a combination of the two — can cause problems for grasses, especially zoysia.
Diseases can strike during spring green-up. The most common is Rhizoctonia large patch, which appears as large areas of blighted grass.

This disease is most active when night temperatures are between 50 and 60 degrees. When conditions are right, it’s common for the disease to become active first in the fall and then again in the spring.

You can see its typical “halo” when the disease is active. Fall and spring fungicide applications can control it. Consult your county UGA Extension agent for proper fungicides and rates.

Applying nitrogen just before or during active infection will increase disease problems.

Cool temperatures make centipede and zoysia slower to green up in the spring.

Microclimates can cause problems, too. Emerald zoysia growing north of Atlanta has been killed by the low temperatures in shaded sites that don’t get much winter sun.

Varietal differences can be troublesome. Some incidences suggest that many types of Emerald zoysia exist in the landscape and green up at different rates.

Cooperative research with the Georgia Crop Improvement Association and Auburn University is under way to evaluate these grass differences.


Lawns in Georgia

Center Publication Number: 147

Use A Lawn Spreader

Source(s): Clint Waltz, Extension Turfgrass Specialist, The University of Georgia

The two basic types of equipment used to apply granular fertilizers or pesticides to lawns are drop spreaders and rotary spreaders. Drop spreaders provide an easy and efficient means of applying granular pesticides and fertilizers with precision accuracy. Rotary spreaders are typically preferred when applying products to larger areas.

Newer models of rotary spreaders have a deflector shield for improved edging around ornamental beds or hard, impervious surfaces. However, you may have to adjust port openings to compensate for a change in distribution. So check the calibration before using deflector shields.

The application rate and distribution pattern are affected by the spreader design, the product (especially weight and density), environmental conditions (wind, temperature, and humidity) and the operator (speed).

Each material will have its own “effective” distribution pattern, so calibrate the spreader for each product being applied. As with all spreaders and sprayers, constant calibration is necessary to assure proper distribution and delivery rate. Consult the owner’s manual for proper calibration and maintenance.

Use it correctly

To use your rotary spreaders properly:

  • Choose a spreader that’s easy to fill and clean, to minimize spills. Make sure the ports (the bottom holes the material falls through) are closed before filling the spreader. And use a cover, especially in uneven terrain.
  • Calibrate and know the “effective” swath width for each material being applied. This will determine the proper overlap. When possible, use flags or other markers to track the effective swath width.
  • Walk at a constant speed — 3 miles per hour is typically recommended.
  • Keep the impeller (the part that “slings” the material) level and parallel to the ground. Tipping the spreader too far can result in uneven spreading.
  • Apply materials while moving forward. Start walking before opening the gate of the spreader, and close the gate before stopping. And avoid sharp turns which make the application uneven. Turn off the spreader before making a turn.
  • To avoid skips and streaks, split the rate and apply in two directions perpendicular to each other. Make a lap around the perimeter, and then fill in the interior of the area.
  • Avoid applying fertilizer or pesticide to nontarget areas (driveways, roads, bodies of water). Blow or sweep material from hard, impermeable surfaces into the turf area.
  • After use, empty the unused material into its original container and wash the spreader thoroughly in an area where the rinse water can’t get into the storm sewage.
  • Grease and oil all moving spreader parts as recommended by the manufacturer. Check and maintain proper tire pressure.


Lawns in Georgia

Center Publication Number: 145

Water Lawns Wisely

Source(s): Clint Waltz, Extension Turfgrass Specialist, The University of Georgia

Just like trees, shrubs, pets and even humans, turf grasses need water to survive. The perception that turf is a water consumer is correct, but we’re all water consumers.


The forgotten benefits

Often forgotten are the environmental benefits of a healthy turf. Grass prevents soil erosion, filters rainwater, traps airborne dust and soot and acts as a noise abatement. Imagine how much louder our lives would be without turf to absorb the polluting sounds of the fast-paced world.

Lawns can act as air conditioners, too. The surface temperature of an actively growing turf grass may be 20 degrees (Fahrenheit) cooler than a dormant turf. As a result, the surroundings are cooler, too, so it costs less to cool buildings.
Don’t forget that grass is a plant. So, through photosynthesis, it converts carbon dioxide to oxygen — which we all require.

Choose and plant appropriately

Many inputs are needed to maintain a healthy turf, but proper water management is the most important. For best water conservation, choose and plant the right grass.

Different types of grasses are better adapted for particular climates. Properly matching the grass with the climate minimizes its water requirements. Georgians are fortunate to have a diversity of climates and an array of turf species to choose from.
Likewise, plan to establish a new lawn at the right time. Trying to plant a lawn just as the climate gets its toughest takes more water and money. Work with nature, not against it.

Water wisely

Once the lawn is actively growing, water wisely. Most turf grasses grown in Georgia need about 1 inch of water per week to maintain normal growth and color. Base their watering on need, not on the day of the week.
Watch for signs of moisture stress, such as wilt, leaf blades rolling or the turf’s failure to bounce back from foot traffic. The right time to irrigate is when you first see signs of stress.

Water, though, with the idea of watering deeply but not often. Light, frequent irrigations lead to shallow, weak root systems that require more money and effort.

Turf roots will “mine” for water. As the soil surface dries, roots explore greater soil depths in search of moisture. Allowing the turf grass a little moisture stress can actually increase rooting depths and, in the long run, save water.
Typically, you should apply one-half to 1 inch of water at a time, depending on the soil.
Pay attention. Avoid watering so much that the soil becomes saturated and water runs off the soil surface. If the water doesn’t make it to the turf’s root zone, it’s of little use to the plant.

Don’t water the pavement, either. Many have tried, and adding water doesn’t cause the asphalt or concrete to grow.
Watering is most efficient in the early morning, when losses from evaporation are less. Research shows that water losses at night are 50 percent less than in midday irrigation. Once again, the plant can use only water in the root zone. Water vapor can’t help the grass at all.

Get help, if you need it

For further help with turf topics, consult your local county agent of the UGA Extension Service. Turf can be a valuable asset to the landscape and the environment, but it’s up to us to properly manage water resources.
Turf grasses don’t waste water. People do.


Lawns in Georgia

Center Publication Number: 151

Calibrating Hand-held Sprayers

Source(s): Clint Waltz, Extension Turfgrass Specialist, The University of Georgia

Hand-held and backpack sprayers are extremely useful for treating small turf areas infested with weeds. But they have to be calibrated to apply the recommended rate of a herbicide.

Most herbicides used in turf grasses control weeds without injuring the turf. But that depends on the rate applied. The rate is usually on the product label as the amount to be applied to 1 acre or 1,000 square feet.

For example, the highest recommended rate of Trimec Classic for Bermuda grass and tall fescue is 1.5 fluid ounces per 1,000 square feet.

Applied at this rate and by the label directions, it will cause only slight injury to labeled turf grasses. But if you apply three times that amount, some turf grasses would be yellow or brown for weeks.

If a sprayer isn’t calibrated, it can’t apply herbicides at recommended rates.

It’s simple

You can use a number of methods to calibrate sprayers. One that’s simple, easy to do and easy to remember is called the 1/128th-acre method.

In this method, you spray 1/128th of an acre. That’s 340.3 square feet. This figures out to 18.5 feet by 18.5 feet. Here’s how to do it.

  1. Mark off a plot 18.5 feet by 18.5 feet.
  2. Fill the sprayer to normal capacity with water.
  3. Pump the sprayer to the pressure normally used to apply herbicides.
  4. Spray water over the plot area while maintaining normal and constant operating pressure.
  5. Record the time in seconds it takes to spray the plot area.
  6. Using the same constant pressure used in step 4, spray into a bucket for the same time (number of seconds) it took to spray the plot area.
  7. Measure the volume of water in fluid ounces.

The number of fluid ounces you collect is equal to number of gallons the sprayer would apply to 1 acre if you use it at the same pressure and walking speed you used in the plot area.

This quick conversion works since there are 128 fluid ounces in 1 gallon of water. It doesn’t get much easier than this. Now all you have to do is find out how much herbicide to add to the pump-up sprayer.

How it applies

Let’s say your sprayer applies 25 gallons per acre. The right rate for Trimec Classic is 4.0 pints, or 0.5 gallons, per acre. So divide 0.5 by 25 to get 0.02, or 2 percent.

Multiply that by the sprayer capacity. A 2-gallon sprayer would hold 256 fluid ounces, and 256 times 2 percent would be 5.1 ounces. So add 5.1 ounces of Trimec Classic to the sprayer. Then fill it to the 2-gallon mark with water.

Remember, you have to walk at the same speed, maintain the same pressure and hold the spray nozzle tip at the same height you used in the plot area.

If you do these things, you’ll apply the recommended rate of the herbicide, control the target weed and, most important, drastically reduce the chance of injuring your turf grass.

Reviewer(s): Clint Waltz, Extension Turfgrass Specialist, The University of Georgia, November 2005.

Center Publication Number: 153

Responsible Lawn Care

Source(s): Clint Waltz, Extension Turfgrass Specialist, The University of Georgia

Water is a precious resource that has long been taken for granted. However, the recent droughts and our rapid population growth has helped focus the need for better resource management.

Often overlooked, our landscapes can help reduce the environmental impact of urbanization. Plants reduce soil erosion, cool the environment, improve air quality, decrease water run-off, filter impurities from the water and enhance community character.

The time has come for everyone to share in protecting our precious water resources and the environment. The following lawn management steps will minimize water pollution from fertilizers, pesticides and sediment while maintaining a healthy, vigorous and attractive lawn.

Lawns and landscapes need water, fertilizers, and sometimes other chemicals to maintain good health. However, improper use of these products can pollute lakes, rivers and streams. In sandy soils, some lawn care products may seep into groundwater and pollute aquifers.

Regardless of whether you hire a commercial lawn care company or do it yourself, insist that the following steps be followed. Make sure your contractor has a Georgia Pesticides Applicators License if they are going to apply pesticides.

For more information, contact your local county Extension office. Additional turf management information is available on the Georgia Turf website.

  1. Prevent Problems
    • Plant the right grass. UGA Extension bulletin 773, “Lawns In Georgia”, explains which grasses grow best in Georgia. It also provides recommended establishment steps for a new lawn and maintenance practices for an established lawn.
    • Plant at the right time so that the lawn gets a good start. Sod is the most effective and rapid means of establishing a lawn. If you establish by seeding, cover with a straw or other type of mulch to prevent soil erosion.
    • Do not try to seed a lawn on a steep slope or in an area that does not drain well. Sod across the slope to protect the soil from erosion and runoff.
  2. Water it Right
    • Water only when the lawn needs it. Most grasses need about one inch of water per week of active growth. It is time to water when the grass appears a dull bluish green, the leaf blades begin to fold or roll and footprints remain as the grass begins to wilt.
    • Do not overwater. You should wet the soil to just below the root depth or generally to a depth of 6 to 8 inches. Apply 1/2 inch of water to a sandy soil and about 1 inch to a clay soil. If runoff occurs during irrigation, stop and allow the water to soak into the soil for a few hours before applying more.
    • Water the grass – not the pavement or street. Place sprinklers and automatic irrigation heads so that the water falls only on the lawn.
    • Water in early morning to reduce evaporation losses and remove disease-enhancing dew.
    • Water newly seeded areas lightly and often enough to prevent the surface from drying out for the first 2 weeks until seedlings become established.
  3. Mow it Right
    • Mow regularly at the correct height (see Table) to encourage deep roots and help keep out weeds. Use a sharp blade and remove only a third of the grass height at one time. Mow when the grass is dry.
    • Leave clippings on the lawn. If you mow regularly and let the clippings decompose on the lawn, you will recycle about 25% of the nitrogen your lawn needs. If you remove clippings, compost them for use as a mulch.
  4. Fertilize it Right
    • Apply the right amount of fertilizer at the right time to maintain a healthy lawn.
    • Do not apply fertilizer before a heavy rain is expected.
    • Test the soil every two to three years to determine if lime, phosphorus or potassium is needed.
    • Choose a fertilizer with some slow-release form of nitrogen to reduce the potential leaching into groundwater, especially on sandy soils or to reduce loss from runoff.
    • Calibrate your spreader every time it is used to apply the right rate and get even distribution.
    • Fill the spreader on a paved surface so spills can be easily cleaned up. Don’t leave fertilizer on paved surfaces where it will wash off. Blow or sweep this fertilizer back onto the lawn.
  5. Use Pesticides Sparingly
    • Have weeds, diseases or insects properly identified before applying a pesticide. Follow the product label directions and time applications when the pest is most sensitive.
    • Do not apply pesticides when heavy rain is likely because some chemicals can leach through sandy soils and pollute shallow water tables or runoff sloping sites or compacted soils.
    • Calibrate your sprayer or spreader to deliver the correct amount of product and ensure even application.
    • Prevent spills. Mix liquid solutions and fill sprayers on grassy surfaces so no liquid spills on pavements. Mix granular materials on smooth, impenetrable surfaces so spills can be easily cleaned up.

**** Mowing Height for Lawn Grasses in Georgia ****
Grass Cutting Height (inches)
Bahiagrass 2 to 3
Bluegrass 2 to 3
Common Bermudagrass 1 to 3
Hybrid Bermudagrass 0.5 to 1.5
Zoysia 0.5 to 1.5
Centipedegrass 1 to 1.5
Carpetgrass 1 to 1.5
St. Augustine 2 to 3
Ryegrass 1 to 2
Tall Fescue 2 to 3

Resource(s):  Lawns in Georgia

Center Publication Number:  143