How to Fertilize Your Lawn Effectively and Responsibly

All plants require basic nutrients which they receive from the soil and water, and they usually benefit greatly from supplemental applications. Grass, in particular, falls into this category. Fertilizing is essential to a healthy, dense lawn that maintains a deep green color and readily withstands weeds and other problems. In order to achieve optimum results, and not waste your money, it’s important that you choose the right fertilizer and apply it at the right time, in the right quantity.

There are many types of lawn fertilizer on the market, as well as home-grown products, that enhance the vigor of your grass. Choosing the right fertilizer begins with understanding the fertilizer’s active ingredients (ie the numbers) and knowing your soil and grass type. You then need to apply it correctly and take precautions not to burn your lawn or risk enviromental damage due to run-off. This article will cover all of these elements with the aim of helping you fertilize in a responsible and effective manner.

TYPES OF FERTILIZER

ORGANIC VS SYNTHETIC

There are two main types of fertilizers: organic and synthetic. Organic fertilizers are made from natural ingredients (once living organisms or their byproducts), such as manures, composts, and agricultural byproducts. Fertilizers from natural organics contain relatively low amounts of nutrients that are released slowly. What that means is there’s a lower chance of damaging the lawn, but you likely need to apply more product. Sythetic fertilizers, on the other hand, are, as the name implies, man made, using chemicals. They come in a wide range of compositions and application times.

In my opinion, organic lawns look better and resist problems better in the long run. Establishing a thick, beautiful organic lawn, however, can take a lot of time. Using synthetic fertilizers you can greatly speed up the process. If you opt for synthetic fertilizer for your lawn, I recommend doing this in conjuction with organics if possible. Check out my article on organic lawn care.

SLOW VS QUICK RELEASE

Organic fertilizers, by their nature, are slow release. Their ingredients must be broken down by the soil for the gradual release of nitrogen and other elements. Whether organic or synthetic, slow-release fertilizers break down their nutrients over a longer period of time, so you can wait longer between applications. every six to eight weeks, depending on your watering, instead of every four weeks. Slow-release synthetic fertilizers are, however, usually more concentrated than organics and easier to apply. Both are unlikely to damage lawns if applied too liberally, and they reduce the chance of the elements leaching away. Most nitrogen in brand-name lawn fertilizers is typically in this form. ‘Time-release’ is a type of slow realease fertilizer that feeds the lawn over many months and is designed for less frequent application.

Quick-release fertilizers, by contrast, are a way to green-up your lawn quickly. They’re relatively concentrated, inexpensive, and easy to apply. Putting down too much or spreading it over a damp lawn in warm weather, however, can burn the grass. Because their nutrients are used quickly, however, you’ll have to apply them more often. I recommend using slow release fertilizer vice quick as it makes application a lot easier and less risky.

LIQUID VS GRANULAR

Liquid fertilizers are spread using a hose and provide a quick, effective way to introduce nutrients rapidly to lawn’s roots. They come in either synthetic or organic forms. Professionals often apply liquid fertilizer, which can cover a large area quickly. However, achieving consistent coverage can be challenging without experience and the right equipment, especially if it’s windy. Granular fertilizers are popular due to their ease of application. This is what I recommend using.

The next thing you need to figure out is what mix of fertilizer to use. This applies equally to both organic and synthetic fertilizers, however I will focus mainly on synthetic. Check out my other article on organic lawn care.

THE NUMBERS

When you buy fertilizer, you’ll see three numbers on the label. These numbers represent the percent by weight of nitrogen (N), phosphorus (P) and potassium (K) in every container and are always listed in the same order, the primary nutrients needed to feed your lawn. So a 24-25-4 bag will have 24 percent nitrogen, 25 percent phosphate, and 4 percent potassium. The rest of the bag usually contains filler material that helps ensure an even application.

WHAT PURPOSE DOES EACH NUTRIENT SERVE?

Each nutrient serves a specific purposes in contributing to the health and hardiness of a lawn. Nitrogen promotes foliar or blade growth and color. This is every lawn’s most important ingredient, and each type of grass demands different amounts to display peak growth and performance. Deficiency results in a yellow-green color and little to no growth.

Phosphorus is useful in encouraging flower and root growth, and early establishment. It stimulates root growth, and accelerates the maturity of plants. It remains in the soil quite well. Deficiency can result in slow or stunted growth

Potassium in lawns enhances the plant’s ability to use nitrogen. It builds drought, heat and cold hardiness, and helps disease resistance. Deficiency can cause weak stems and/or slow growth.

WHAT TYPE OF LAWN FERTILIZER SHOULD I USE?

The best way to select a fertilizer grade is to have your soil tested. The soil test report will recommend a fertilizer grade for your use. Check out my article on soil testing. The soil test kit I recommend is Soil Savvy. Check the price on Amazon. I recommend doing a soil test every few years, or if you just moved into a new home, you may want to do one annually, or until you start seeing results.

This is a professional-grade soil test kit that provides easy to understand fertilizer recommendations tailored to your specific soil. The report includes soil pH and 14 nutrients including (N,P,K) and lists which nutrients are deficient. This eliminates over application of the nutrients they don’t need. Phosphorus, for example, should never be applied unless your soil test indicates a deficiency. This is a common mistake. Typical fertilizer grades recommended for lawns and gardens include: 5-10-5, 5-10-10, 10-10-10, 8-0-24, and 6-6-18.

Regarding soil PH, poor lawn growth could equally be attributed to incorrect PH levels as it could to lack of nutrients. So if your PH is off, you’re better off investing in lime in the spring rather than fertilizer. Not only is this a cheaper solution, getting your pH level right increases the effectiveness of any fertilizer down the road. My overall lawn has a Neutral Ph, however I have one spot with high acidity that needs treating with lime.

GRASS TYPES

Different types of grasses need different amounts of nitrogen to keep them thick and healthy. The following table lists the yearly nitrogen requirements for 1,000 square feet of the most common lawn grasses. Source: Lance Walheim, The National Gardening Association

My lawn is a mix of tall fescue, perennial rye, and Kentucky blue grass. See my article on Grass Types to help identify the grass in your lawn. Given my grass and soil type I use three types of fertilizer on my lawn. For overseeding and new grass I use a starter fertilizer (24-25-4). During the summer I use a a 30-0-3 such as this one from Scotts.  For my fall application, I use a fertilizer with a higher amount of phosphorous (32-0-10) Amazon link.

HOW OFTEN SHOULD I BE APPLYING FERTILIZER?

How often you fertilize affects not only lawn appearance, but also maintenance level. The more you fertilize, the more you’ll have to mow. For most people I would recommend fertilizing no more than four to five times per year. Spring, summer, early fall and after the first frost for cool season grasses. Once more during the summer if conditions dictate. If you’re in drought conditions, skip the summer application.

The first feeding in the spring should take place when the soil temperature reaches 55 degrees Fahrenheit (or 13 degrees Celsius) just before grass enters its peak growing phase. At this temperature the lilacs begin to blossom and the grass starts growing. For most parts of the US and Canada, that means the first feeding should take place by between mid-April and early May.

The second feeding should happen about four weeks later, in mid to late May or early June. Then fertilize every six to eight weeks after that through October.

Fertilizing in the early fall keeps your lawn beautiful and healthy throughout the autumn months. Fall’s cooler temperatures provide the perfect setting for your lawn to regain strength. Fall’s morning dew provides moisture to help turf absorb the fertilizer.

In the northern US and Canada, where winters are cold, your last fertilizing should be in the late fall (usually in October or November). Cool weather grasses go dormant over the winter and store energy in their roots for use in the spring. A late fall fertilizer will enable the lawn to green up much quicker in the Spring. The fall feeding is the most important application of the year. Never skip this application. Apply fertilizer before grass starts to discolor with the arrival of cold weather.

When to Fertilize Warm-Season Grasses

If you live in southern areas where lawns feature warm-season grasses, fertilize turf in the late spring or early summer, just before your grass begins its most active growth. Make a second and third application in mid and late summer. If your warm-season lawn goes dormant in winter, don’t fertilize after the first of September.

Do I need to fertilize more than once a year?

Many lawn care professionals state that cool-season grasses can get by with just one fertilizer application per year. If you choose to fertilize once a year, do it in September for cool-season, Northern grasses, and early June for warm-season, Southern grasses. Look to your lawn as well to provide cues on potential nutrient shortfalls. Pale, yellow-green grass, for example, is a tip-off that your lawn may need more nitrogen.

Is there a best time of day to fertilize your lawn?

The best time of day to fertilize is when its cooler, such as the morning or early evening. Both times avoid the warm daytime temperatures that work against fertilizer. Don’t apply fertilizer in hot, humid weather.

Fertilize on a windless day when the temperature is below 90 degrees Fahrenheit (32 degrees Celsius).

Is it better to fertilize after mowing?

Yes. It is best to apply fertilizer after the lawn has been mowed so it has a few days to absorb the fertilizer prior to mowing again. It also exposes the soil, which helps the fertilizer work itself in more efficiently.

Mulching = Free fertilizer

If you mow often enough, leaving the clippings on the lawn adds nitrogen to the soil. Mulching all year long can actually reduce the amount of fertilizer your lawn needs by 25 percent or more.

In the fall, the addition of dried leaves speeds up the composting process because, alongside grass clippings, one is a carbon source and the other is a primarily nitrogen source. This is a one-two punch in the composting world, which breaks down more quickly than nitrogen alone from the clippings.

HOW TO APPLY FERTILIZER

How much fertilizer should I put on my lawn?

Don’t guess how much fertilizer you need and what setting you use. For best results, closely follow the application directions on the product. And, of course, follow your soil test fertilizer recommendations.

Recommendations for lawn fertilizers are usually given in actual nutrients per given area. Experts recommend no more than 1 pound of nitrogen per 1,000 square feet for each application and between 3-5 lbs./1000 sq. ft. per year. To determine the total weight of nutrient in the bag, multiply the percent of that nutrient by the bag weight. For example, a 50 lb. bag of 10-6-4 fertilizer contains 5 lbs. of nitrogen (10% x 50 lbs). To double-check your calculations, use the Purdue University Turf Fertilizer Calculator www.agry.purdue.edu/turf/fertcalc/Fertilization%20calc.html.

What Equipment should I use?

The best way for homeowners to apply fertilizer is with a walk-behind broadcast spreader. Broadcast spreaders are easier to use than drop spreaders and since they disperse the fertilizer a wider distance, there’s less chance you’ll end up with stripes in your yard caused by not overlapping the rows properly. Broadcast spreaders are usually cheaper as well. And the same spreader can be used for seed, lime etc. Buy a quality spreader and keep it well maintained. I recommend the Earthway 2150, pictured above. Check price on Amazon. Solid linkages offer more reliable spread-rate control than cables, which tend to stretch. And pneumatic tires make it easier to maneuver. A handheld broadcast spreader works well for fertilizing small lawn areas or areas in your lawn that require a different fertilizer rate. I use this Scott’s spreader.

Calibrating your spreader

If your spreader is functioning correctly and you’re using the recommend settings for spread rate that should be sufficient. I recommend, however, that you periodically verify your application rate. I find the easiest way to do this is to put a known quantity of fertilizer in your spreader and then mark off a 100 or 200 sq ft section of your lawn. Once you’ve done this section, calculate what the spread rate is per 1000 sq ft. 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.

FERTILIZING STEPS

1. Check the packaging for proper spread rates and adjust your spreader to the recommended setting.

2. Fill the spreader halfway up. Before filling the hopper, make sure the bottom hole is closed. It’s a good idea to fill it on a tarp, so you can easily gather any spilled fertilizer.

3. Apply fertilizer around the perimeter of the lawn first. Then  move back and forth across the lawn in an systematic pattern, walking evenly and at a medium speed. Overlap application strips slightly to ensure that you cover the whole lawn evenly with fertilizer.

4. After you’re done, sweep up and collect what remains on hard surfaces, such as your driveway, sidewalk or street. If fertilizer is left on these surfaces, rain will eventually wash it into water features and storm sewers. Never apply fertilizer to frozen ground, close to wetlands, rivers, streams, lakes and ponds. Rinse your spreader thoroughly with a garden hose.

5. Keep records of what and how much you apply and when you apply it.

IS IT OK TO WATER BEFORE AND AFTER FERTILIZING?

A day or two before applying fertilizer, it’s helpful to for you lawn to have a good soaking, either through irrigation or heavy rain, as fertilizer needs moisture to break down. Contrary to what some people think, the more you water your lawn, the more fertilizer it needs. As the grass grows, it uses more nutrients.

Time Fertilization with the Weather

If heavy rains are in the forecast, hold off fertilizing until the heavy rains have passed. Lawns should not be fertilized prior to a heavy rainfall. This will cause the fertilizer to runoff into nearby storm drains and waterways, instead of sinking into the soil, polluting the environment.

After the grass dries, apply fertilizer. Give light amounts of water to give the fertilizer the opportunity to be absorbed by the soil. Light watering also washes fertilizer off the grass blades which helps prevent fertilizer burn and puts the fertilizer in contact with soil where it’s needed.

Be sure to read what the fertilizer label says about when to water . Some fertilizers require you to wet the lawn prior to application. Avoid applying fertilizer during a drought when a lawn has browned or withered from lack of moisture. Fertilizer applied in a drought is more likely to burn a lawn than to help it grow.

How much does it cost to fertilize your lawn?

You’ll spend about $30 to $60 per application for an average 1/4-acre lot. Spend time accurately measuring the size of your lawn so that you buy the right amount of fertilizer.

CONCLUSION

Remember, start off by testing your soil and identifying your grass type. Once you know what nutrients your lawn needs, use slow release granules and apply them with a quality walk behind broadcast spreader. Fertilize at the right times throughout the year. Be systematic when applying and pay attention to the weather.  Fertilizing the right way saves money and the environment!