How to Fertilize Your Lawn

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When it comes to lawn fertilizer there are a few things you can do to create a hearty, healthy lawn that's less susceptible to weeds and disease. With tips on when to fertilize lawn, how to save money and what mistakes to avoid, you can yield a yard you've always dreamed of!

Avoid the top 4 lawn fertilizer blunders

When it comes to lawn fertilizer, mistakes are easy to make. I know, because I’ve been in the grass business for a very long time. And I can tell you that professional turf managers and homeowners tend to make the same four mistakes when they feed their grass.

Read along, avoid these lawn fertilizer blunders and you’ll be thrilled with your lawn and get the most for your buck.

Meet the pro

Joe Churchill has worked in the professional turf industry for more than 30 years. He is a branch manager for Reinders, a major turf supply and equipment distributor in the Midwest.

Project step-by-step (5)

Step 1

Failure to test the soil

Test the soil

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You can collect your own samples by randomly pulling 10 to 12 individual soil samples from your lawn to a depth of 3 to 4 in. Make sure there is no vegetation or excessive root mass in the soil sample. Mix together the soil samples and put about a cup of this mix in a plastic bag. Write your name on the bag and send it off for testing.

“I can’t tell you how many times I’ve talked to a professional or a homeowner who has never tested their soil. Big mistake!”

When I’m asked to help bring a homeowner’s lawn back to life, the first thing I do is to make sure they have their soil professionally tested. Think of it as a checkup for your lawn. The results will provide important information that will help determine what type of grass fertilizer you should use and how often you should apply it.

You can collect your own samples by randomly pulling 10 to 12 individual soil samples from your lawn to a depth of 3 to 4 in. Make sure there is no vegetation or excessive root mass in the soil sample. Mix together the soil samples and put about a cup of this mix in a plastic bag. Write your name on the bag and send it off for testing.

Most often, a soil test will focus on measuring major nutrients like phosphorus (required for good root development) and potassium (needed to remedy environmental stresses). If your soils are lacking in these major building blocks, your lawn will suffer.

Another important piece of information received from a soil test is your soil’s pH. Most lawn grasses like a soil pH in the range of 6.5 to 7.0. If your lawn’s soil pH is too low or too high, the fertilizer you use may not work very well. Soils with a low pH, like 5.5 or 6.0, will require applications of lime to “sweeten” the soil. Soil pH values above 7.5 will require soil sulfur or a lawn fertilizer containing sulfur to bring the pH down.

If your soil test results recommend adjustments to correct nutrient or pH issues, it’s wise to test annually until the problems are corrected. If your soil test does not reveal any issues, test about every three years to monitor the health of your soil.

The best time to test your soil is early spring just before your lawn comes out of dormancy. Don’t collect samples after grass fertilizing. This will skew the results. And don’t use do-it-yourself kits! They may be less expensive, but they aren’t very accurate. Your county extension office, reputable garden center or local university can help you test your soil accurately, interpret the results and then offer solid recommendations for fixing any soil problems.

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Step 2

Too much lawn fertilizer

Less grass fertilizer, more even distribution

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Dial back the rate of lawn fertilizer applications to 1/2, then make two passes with your spreader at right angles.

“I bet at least 3 out of every 5 homeowners use way more lawn fertilizer than they should.”

Many retailers promote a four-step lawn fertilizer schedule for homeowners. Fertilizing more than four times a year is overkill. In fact, most homeowners could get by with two every year. You can cut back on the amount of grass fertilizer you need by knowing when to fertilize lawn based on time of year. More on that later.

If you apply too much lawn fertilizer, especially in sandy soils, a good share of it will leach through the soil and make its way into our precious groundwater, lakes, streams and wetlands. Lawn grasses only need a certain amount of food. More isn’t always better.

Unlike us humans, lawn grasses don’t know how to stop eating when they’re full! This luxury consumption of nitrogen, phosphorus and potassium actually makes the lawn grasses weak and more susceptible to disease. Excessive grass fertilizer will create too much thatch, which will ultimately choke out your lawn. Too much lawn fertilizer also means you’ll be mowing far more often than necessary. Too much mowing means excessive soil compaction, exhaust and noise pollution and excessive wear and tear on your mower.

When it comes to a lawn fertilizer schedule, applying more than four times a year is a waste. Save time and money by being more judicious in your use of lawn fertilizer.

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Step 3

Fertilizing at the wrong time

“Many homeowners don’t follow a lawn fertilizer schedule. They fertilize when they think their lawn needs it, when they have time or when the stuff is on sale.”

Here’s when to fertilize lawn: If your lawn fertilizer schedule is once per year, apply it around Labor Day. That’s when your lawn is the hungriest and when it will respond best to the nutrients it receives. Fertilizing at this time will help replenish food reserves after a long, stressful year of growing and before the harshness of winter sets in.

If your lawn fertilizer schedule is twice per year, apply the second application about the middle of October. This acts like a “second helping” of much-needed food going into winter. A third application can be added in mid to late spring and can be combined with your crabgrass preventer. A fourth application, if you feel the need, can be added mid-summer. Watch the weather when applying midsummer fertilizers. Fertilizing during hot, humid weather can harm your lawn. An exception would be using an organic fertilizer. They are much more lawn friendly during the dog days of summer.

In the spring, apply just enough fertilizer to help green up your lawn. About half the normal amount will do. Even without fertilizer, your lawn naturally grows quickly as soon as temperatures become consistently higher. Have you ever noticed that grass grows fastest in the late spring and early summer? Why promote even more growth at this time by fertilizing?

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Step 4

Getting careless

Spread with care

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As much as fertilizer can be a valuable tool to keep a lawn healthy, dense and great looking, it can also create environmental concerns if not used responsibly.

“It’s not the use of phosphorus and other nutrients that are creating environmental issues; it’s the misuse of them.”

As much as fertilizer can be a valuable tool to keep a lawn healthy, dense and great looking, it can also create environmental concerns if not used responsibly. Too often I see people not paying attention when fertilizing. They’re in a hurry or just don’t care. They think the little bit of fertilizer that gets washed off your lawn and into the street doesn’t matter. But what if all your neighbors thought this? Or worse yet, every lawn owner in your town? Not only can we help our environment by using less fertilizer, we can do even more by making sure it stays where it’s intended.

Never apply any type of fertilizer close to wetlands, rivers, streams, lakes and ponds. We’re trying to grow lawn grasses, not aquatic weeds. Heavy nutrient loads in these types of water features will create excessive weed growth and algae blooms. Nobody wants that. Stay at least 6 to 8 ft. away from water when applying fertilizer.

After you’re done fertilizing, sweep up and collect what remains on hard surfaces, such as your driveway, sidewalk or street. If fertilizer is left on these surfaces, rains will eventually wash it into water features and storm sewers.

Never apply fertilizer to frozen ground. This can easily happen in the spring if you’re anxious to apply your crabgrass preventer. If the ground is still frozen, it’s too early to apply crabgrass preventer anyway. In short, be a good environmental steward.

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Step 5

My take on organic fertilizers

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Organic fertilizers are becoming more popular with lawn owners because of the idea that they are more environmentally friendly. Quality organic fertilizers will contain meal-based nutrients (bone meal, feather meal, blood meal, fish meal) or some may contain poultry litter. A complete natural organic lawn food will have low NPK (nitrogen, phosphorus, potassium) numbers, most always below 10. It’s best to apply these fertilizers during the warmer growing months, from May through September, depending where you live. Organics help feed your lawn by stimulating microbial activity in your soil, creating a healthier medium in which your grass can grow.

They are safer to use and will not harm your lawn like some conventional fertilizers will, especially during the hot summer months. They work a bit slower, however, so you’ll need to be patient.

You’ll also discover they are much more expensive. All that said, give them a try!

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Recap: lawn fertilizer dos and don’ts


  • Test your soil first.
  • Use test results to choose the right fertilizer.
  • Spend time accurately measuring the size of your lawn.
  • Try an organic during the hot summer months.
  • Buy a quality spreader that best fits your needs.
  • Accurately calibrate your spreader to make sure you apply the right amount.
  • Keep your spreader well maintained.
  • Keep records of what and how much you apply and when you apply it.


  • Test your soil after you have fertilized.
  • Guess on how much fertilizer you need and what setting you use.
  • Apply fertilizer in hot, humid weather.
  • Apply fertilizer near water features, on hard surfaces or on frozen ground.
  • Use phosphorus unless your soil test indicates a deficiency.
  • Apply more than four times a year.
  • Use liquid fertilizers on your lawn.
  • Use a drop spreader in big lawns.
  • Bag your clippings.