Water, fertilizing and mowing lawn-care tips

The right way to water, fertilize and mow your lawn

Last updated: July 2013

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Assuming you've got the right grass for your area, lawns succeed or fail primarily on how well they are managed. The right watering, fertilizing, and mowing mean the difference between a lush green carpet and a spotty landscape that's more crabgrass than lawn.

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Learn more about lawn care, equipment, and maintenance with our Complete Lawn & Yard Guide.

Watering basics

Water Watch
A rain gauge is best for keeping precise tabs on your watering.

Improper watering is the culprit behind many lawn problems, especially in the West where healthy grass depends almost entirely on sprinklers. Too little can encourage crabgrass and other weeds that thrive in dry soil. Too much can invite diseases and is wasteful, especially where water is scarce.


Before planting grass, add compost or other soil amendment to the soil to improve its ability to hold water.

How much water

Most lawn grasses need roughly 1 inch of water per week through the growing season. Lawns may need little supplemental water in the humid Southeast or rainy North. But you'll need that extra 1 inch per week of watering if you live in the Southwest where humidity is low and summer drought is common. Also remember that any lawn needs more water after a hot, dry week than it will after a cool, humid week.

Cut your grass higher during hot spells. Taller grass shoots provide better shade for the soil beneath and require less water. Taller grass also has longer roots which can absorb more water deeper in the ground.

Rain gauges are the most precise way to see how much water your lawn is getting. Place them where they're exposed to both sprinklers and rainfall. Use several gauges around each sprinkler, then run the sprinklers for 10 minutes. If the water in the gauges measures one-quarter inch, for example, it will take 40 minutes to apply 1 inch of water. You can also measure how quickly your sprinklers apply water by setting empty soup cans around them and then measuring the water inside the cans.

In rainy areas, have a portable sprinkler and hose in case of drought. Use a timer (about $25) or automatic shutoff to manage watering efficiently. For drier climes, you'll save time and money with an automated underground sprinkler. Maximize these systems' efficiency by using moisture and rain sensors to override an automated program.

Avoid waste by keeping water off sidewalks, driveways, and other non-lawn areas. Use sprinklers that apply water no faster than the soil can absorb it. Different soils absorb water at different rates; sandy soils absorb it quickly, clay soils slowly. You'll know it's time to stop when water runs off the lawn. Choose sprinklers or sprinkler heads that are matched to your soil.


If your sprinklers apply water too fast, water only to the point of runoff and then stop. Wait about 20 minutes before turning the sprinklers on again.

How often to water

Water only when you must and then water thoroughly. Roots will grow only as deep as the soil is moist, and deep roots make grass hardier and more resilient. Deep but infrequent watering also discourages pests and disease by letting the lawn dry thoroughly between waterings. That works out to once or twice weekly through the growing season in the West and other areas where grass requires watering.

Dial in extra water if you see signs of drought. Persistent footprints are the major one for all regions, indicating that grass blades are losing resilience. Most lawns also have one area that dries out first. Watch that area closely, using it as an indicator for the entire lawn.

Why morning is best

Use sprinklers in the early morning when there's less wind to blow the water and less sunlight to evaporate it. Morning watering also discourages pests and disease by giving the lawn the rest of the day to dry.

Water sensors can improve the efficiency of in-ground sprinkler systems. The EPA's WaterSense program includes more than 300 certified landscape professionals nationwide who can design efficient irrigation systems or perform efficiency audits on existing systems. To learn more, go to www.epa.gov/watersense.

The facts on lawn fertilizing

Pale, yellow-green grass is a tip-off that your lawn needs more nitrogen, the key ingredient in fertilizer. Using the right fertilizer at the right time is the quickest and easiest way to provide that nitrogen so that you lawn can better withstand pests and extreme heat and cold.

Where to begin? A good first step is to obtaining the proper soil pH through a soil test. Getting the right pH level (usually by adding lime) increases the effectiveness of any fertilizer. It is better to invest in lime in the spring rather than fertilizer.

Use a fertilizer formulated specifically for lawns and follow the directions on the label. That includes using the spreader the label stipulates so that you can use the recommended setting. But you'll still be faced with a plethora of choices. Using the wrong kind in the wrong way can hurt more than help. Indeed, too much fertilizer can pollute the ground and encourage lawn pests. Here's what's available and how to apply it:

Kinds of lawn fertilizers

There are three main types. The major difference is in how quickly their nitrogen gets to the grass roots.

Natural organic fertilizers include manures, composts, and agricultural byproducts that might otherwise be wasted (see our Web site, www.GreenerChoices.org, for composting tips). Natural organics contain relatively low amounts of nutrients that are released slowly, so using too much probably won't damage the lawn. But you'll need to apply more of them. What's more, some may include weed seeds. Those that don't include alfalfa, blood meal, and soybean meal.

Slow-release chemical fertilizers are more concentrated than natural organics and easier to apply. They're also unlikely to damage lawns if applied too liberally. Half or more of the nitrogen in brand-name lawn fertilizers is typically in this form, called water-insoluble nitrogen (WIN). These fertilizers don't produce an immediate effect, but that's usually better for the grass.

Fast-release fertilizers are one way to green-up your lawn quickly. They're relatively concentrated, inexpensive, and easy to apply. But putting down too much or spreading it over a damp lawn in warm weather can burn the grass. Because their nutrients are used quickly, you'll have to apply them more often.

When to fertilize

If you fertilize once a year, do it in September for cool-season, Northern grasses, and early June for warm-season, Southern grasses. Otherwise, make two to three applications in fall, one month apart, and one in spring for cool-season grasses; three applications are needed during the summer for warm-season grasses.

How much

Lawn fertilizers contain nitrogen and, usually, phosphorus and potassium in that order. You'll know how much a fertilizer contains by checking its label. A 100-pound bag labeled 20-0-0 has 20 pounds of nitrogen, and no phosphorus or potassium, for instance.

Lawns typically need only 25 percent as much phosphorus and 50 percent as much potassium as they do nitrogen. So don't apply phosphorus or potassium unless it's needed. A soil test is the only way to tell (search the Web using the words "soil testing [your state]").

Recommendations for lawn fertilizers are usually given in actual nitrogen over a given area. Experts recommend no more than 1 pound of actual nitrogen per 1,000 square feet for each application. Once you know a fertilizer's nitrogen concentration, calculate how many times that first, nitrogen-percentage number in the fertilizer mix goes into 100, then apply that many pounds of fertilizer per 1,000 square feet.

For example, figure on using 5 pounds of 20-5-10 fertilizer, 10 pounds of 10-2 1/2-5 and so on. The total actual nitrogen applied per year should be 3 to 5 pounds. To double-check your calculations, use Purdue University's Turf Fertilizer Calculator (www.agry.purdue.edu/turf/fertcalc/Fertilization%20calc.html).


Returning mulched clippings to your lawn rather than bagging and disposing of them reduces the need for lawn fertilizer by 30 to 50 percent. That equals roughly 2 to 2.5 pounds of fertilizer per year to put down 4 pounds of actual nitrogen.

Calibrating a drop spreader

Fill the spreader with fertilizer, note its setting, and operate it over 50 feet with a collection pan or strip of plastic sheeting beneath it. Weigh the amount of fertilizer that fell on the pan or strip. Calculate the square footage you covered (50 feet times the spreader's width in feet). Then use that as a guide to how much the spreader will deliver over the 1,000 square feet specified on fertilizer labels. For example, if the spreader dropped 1 pound of fertilizer per 100 square feet, it will drop 10 pounds per 1,000 square feet at that setting. Increase or reduce the amount delivered as needed.

Mowing tips for healthy lawns

The Lowdown
Mowing short can remove too much of the grass leaf.

Proper mowing plays a significant role in the health of your lawn. Mowing often enough at the right height encourages deeper roots that can better withstand drought, pests, and weed invasions.

The most critical tip: Avoid mowing off more than one-third of a grass blade's height at once. For example, if you want a 3-inch mowed height, mow when the grass is just over 4 inches tall.

How often

Mowing once each week may be easiest for most homeowners. But doing it every 4 to 5 days during peak growth and every 8 to 10 days during slower growth reduces stress on your lawn and helps keep it at its peak. Cool-season grasses grow fastest in the cooler temperatures of spring and fall, when they need more frequent mowing. Warm-season grasses grow fastest during midsummer and need more mowing then. (See grass guide and zone map.)

How high

Taller grasses typically have deeper roots. But mowing too high often looks messy, while mowing too low starves the lawn by removing too much of its nutrient-producing leaf surface. Cutting below the green leaf blades into the brown grass stems, called scalping, weakens the grass plant and leaves it vulnerable to aggressive weeds or pests. (See grass guide and zone map for optimal mowing heights.)

Suppose you miss a mowing session. Adjust your mower upward to reduce the height gradually without taking off more than a third of the grass blade with each mowing. Then readjust your mower to its normal height.

Which type of mower

Reel mowers cut with a scissorlike action and are best when mowing lower than 1.5 inches on even ground--typical for golf greens and sports arenas. Rotary mowers and riding tractors cut with spinning blades and work best at 2 inches and higher. Most homeowners prefer rotary mowers because of their speed and ability to cut taller grass and weeds. Nearly all now include a mulching mode that returns clippings to the lawn. (See our continually updated Ratings and recommendations for push mowers, self-propelled mowers, and lawn tractors.


Be sure blades are sharp. Mow when grass is dry, since wet mowing leaves clumps and clings to the blades and deck. Also try mowing at 3 or 4 different angles on consecutive mowings to spread out wear and compaction from the mower wheels.

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