The Quick and Easy Guide to Fertilizing Your Lawn

Spring is the perfect time to fertilize your lawn.

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The best time to fertilize your lawn is in the spring, when the soil temperature reaches 55 degrees Fahrenheit. You'll know when the soil warms up to 55 because the lilacs begin to blossom and the grass starts growing. For most parts of the country, that means the first feeding should take place by about mid-April. So if you haven't started, now's the time.

Jeff Turnbull, president of LCS Lawn Service in the Twin Cities, offers some simple-to-follow fertilizing advice.

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Timing Is Everything
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The very best time to fertilize your lawn is in the spring, when the soil temperature reaches about 55 degrees Fahrenheit. You'll know when the soil warms up to 55 because the lilacs will begin to blossom and the grass will start growing. For most parts of the country, that means the first feeding should take place by about mid to late April.

Know the Numbers
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When you buy fertilizer, you'll see three numbers on the label. These numbers show the percentage of nitrogen, phosphate, and potassium, respectively, which are the primary nutrients needed to feed your lawn. So a 20-5-10 bag will have 20 percent nitrogen, 5 percent phosphate, and 10 percent potassium. The rest of the bag usually contains filler material that helps ensure an even application. The 20-5-10 mixture is a good basic mix for spring.

Use a Slow-Release Fertilizer
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Slow-release fertilizers break down their nutrients over a longer period of time, so you can wait longer between applications. "With slow-release, you can go every six to eight weeks, depending on your watering, instead of every four weeks," Turnbull says.

He recommends a slow-release that contains nitrogen but not too much. "The most nitrogen you need on a lawn is one-tenth of a pound per week. The grass can't get any greener than that. If you use more, you're only going to make the grass grow faster so you have to mow more often," Turnbull says. "The secret is to get it as green as possible without growing it fast." Turnbull recommends giving your lawn between two and three pounds of nitrogen over the entire growing season. "If you go with 25-0-4, that gives you one pound of nitrogen, so over four weeks, that's a quarter pound per week," Turnbull says. "That's too much. At that point, you're baling hay instead of mowing a lawn."

Go with Granules
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When professional landscapers apply fertilizer, they often drive up in a tanker truck and spray your entire lawn in an impressively short amount of time. But pros do this every day, so they know how to factor in for the wind and make sure the yard gets even coverage. And they have the proper equipment to get the job done right. Homeowners, on the other hand, should use granules, which are super simple to apply using a spreader.

"Granular fertilizer is very easy to apply accurately," Turnbull says. "When you're spraying fertilizer, it's tough for a homeowner to get a consistent, even application across the entire lawn."

Plan for Five Applications—Starting in April
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Turnbull recommends giving your lawn its first feeding of fertilizer in the spring—mid to late April—when soil temperature reach 55 degrees Fahrenheit. Your local university extension office can give you the soil temperature in your neighborhood, but as mentioned earlier, a good indication of 55-degree soil is when the lilacs blossom and the grass starts to grow.

The second feeding should happen about four weeks later, around mid-May. Then fertilize every six to eight weeks after that straight through to October.

For the third feeding, use an organic material, such as manure, instead of a traditional lawn fertilizer. And remember that fall feeding is critical, too. "Grass continues to grow throughout the fall. The roots are going down into the soil and they need fertilizer," Turnbull says. "In fact, this is the most important application of fertilizer for the whole year." And use a fall fertilizer that’s slightly higher in phosphorous and potassium, which will promote better root growth.

Remember to Water
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Contrary to what some people think, the more you water your lawn, the more fertilizer it needs. "With more water, there is more growth, so you need more fertilizer," Turnbull says. "As the grass grows, it uses more nutrients." If you have an automatic sprinkler system, you should fertilize your lawn about every six weeks. Without a sprinkler system, you can wait an additional two weeks between feedings.

Also, be sure to carefully read the fertilizer label to learn whether you should water the lawn before or after applying the fertilizer. Granulated fertilizers need moisture to break down, and some fertilizers require you to soak the lawn prior to application.

Close the Hopper and Fill ‘er Up
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When you're ready to pour fertilizer into the spreader, park it in the driveway or, if you can't, at least put a tarp under it. This will keep any spilled granules from accumulating in one spot on the lawn, where they can burn and kill the grass.

"And make sure your hopper is shut before filling up the spreader," Turnbull says. "That's lesson number one that everyone forgets at least once." (If the hopper is left open, the fertilizer will pour right through onto the ground.)

A broadcast spreader is a better choice than a drop spreader for homeowners. Broadcast spreaders are easier to use, and since they disperse fertilizer a wider distance, there's less chance you'll end up with strips in your yard caused by not overlapping the rows properly. Plus, broadcast spreaders are significantly cheaper, starting at about $30; drop spreaders cost about $85.

For small yards and narrow strips of grass, use a handheld broadcast spreader, which has a hand crank. You can buy one for as little as $10.

Regardless of what type of spreader you use, be sure to walk at a consistent, steady pace as you apply the fertilizer. Failing to do so will cause the fertilizer to be spread too thin in some spots and too thick in others.

Apply, but Don't Over-Apply
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The fertilizer label will give you the application rate, but don't follow it. "Start out at half of what's recommended on the bag," Turnbull says. "One of the biggest mistakes homeowners make is applying fertilizer with the spreader wide open." He recommends spreading the fertilizer at half or slightly less than half the manufacturer’s recommended rate.

Start by applying fertilizer around the perimeter of the yard first, and then fill in the middle, working in one direction. Then, spread it again, moving in a perpendicular direction. This crisscrossing pattern ensures much better coverage and helps prevent over-applying the fertilizer. "When it comes to spreading fertilizer,” Turnbull says, “too little is better than too much. I always recommend erring on the side of too little.” A heavy dose of fertilizer isn’t only a waste of money, but it can burn and kill the grass.

Since you're applying the fertilizer at half the recommended rate, it won't spread out very far, so you don't need to estimate how much spacing to keep between rows. "Go from tire-track to tire-track on the spreader," Turnbull says. "This will guarantee good, even coverage."

And be sure to check the weather forecast prior to fertilizing. If you apply the fertilizer right before a downpour, much of the fertilizer will be washed away.

Sweep Up Stray Granules
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No matter how careful you are, the spreader will occasionally throw fertilizer onto your driveway, sidewalk, or patio. If that happens, sweep it up rather than letting the rain wash it away.

"If you don't sweep up the excess fertilizer, it just adds extra pollution," Turnbull says. "It gets washed away into storm drains and then ends up in the rivers, streams, and lakes. Sweeping up the fertilizer is good for the environment."

Finally once you’ve finished fertilizing your lawn, pour any leftover fertilizer out of the spreader and back into its original bag. Tightly seal the bag and store it away in a cool, dry place, well away from any children and pets.

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