Fertilizing your lawn? Use a Correctly Calibrated Spreader

By Jaime Staufenbeil - Milorganite Agronomist
May 22, 2017

Spreaders are used to evenly distribute fertilizer and grass seed across your lawn. There are two types: drop and broadcast, also known as a rotary spreader. There are two types of broadcast spreaders: walk-behind and hand-held. All spreaders have a hopper to hold the product and an adjustable opening to control the volume of fertilizer or seed being distributed. Selecting the right spreader for you depends on your lawn and preferences.

Drop spreaders

Drop spreaders are very accurate as they distribute even rows of fertilizer exactly where you want it. It’s important that you overlap wheel marks to ensure the entire lawn has been covered. The rate at which you walk directly impacts how much product is distributed.

Drop spreader for fertilizing the lawn

Drop spreader considerations

  • Works well for smaller lawns, under 5,000 sq ft.
  • Easy to operate.
  • Provides precise, controlled coverage.
  • Easy to navigate around obstacles and tight spots.
  • Product distribution generally not impacted by the wind.
  • Less product will end up on your driveways, walks, and paths.

Drawback: Drop spreaders cover a smaller area of lawn per pass compared to broadcast spreaders, which means it’ll take a bit more time to fertilize your lawn.

Broadcast spreaders

Broadcast spreaders distribute fertilizer in a fan-like pattern in all directions and cover a wider area per pass than drop spreaders. The rate you walk and the spreader’s hole size impact how much product is distributed. Broadcast spreaders naturally distribute less product toward the edge of its broadcast range. Check the spreader manual for tips on how far various types of fertilizers are thrown. Like drop spreaders, make sure to overlap passes so you don’t end up with stripes.

Broadcast spreader for fertilizing your lawn.

Broadcast spreader considerations

  • Greater coverage area works well for large lawns.
  • Covers more lawn in less time.
  • Walk-behind and handheld models are available.
  • Hopper capacity of walk-behind models are generally larger than drop spreaders; fewer refills.
  • Some broadcast spreaders have a side-shield feature that allows you to shut off half of the spreader, which is particularly helpful for applying product around the perimeter of your lawn and avoiding hard surfaces and landscaping.

Drawback: Product can be distributed where you don’t want it, such as in gardens or on driveways, walks, and paths. This is a problem if you’re applying an herbicide, which would be detrimental if it got into your flower bed. This isn’t a concern when using Milorganite, as it can be used on lawns, flowers, shrubs, and vegetables. Make sure to clean up any product from hard surfaces so it doesn’t end up in waterways.

Spreader settings

Most homeowners don’t want to calibrate their spreader to discover the correct setting. You just want the setting number, right? Unfortunately, each spreader is slightly different and so are you.

Use spreader settings and application rates as guides. Many variables impact your spreader’s setting to reach optimal application rates, including the type, age, and condition of your spreader, as well as the rate at which you walk. The best way to ensure you’re applying the proper amount of Milorganite is to calibrate your spreader. Below are six easy steps you can follow.

Milorganite is very forgiving compared to synthetic fertilizers or those that contain herbicides. It won’t burn your lawn, so you don’t have to worry much about over application. Milorganite can be used throughout your yard—on lawns, shrubs, trees, flowers, and vegetables—so you don’t have to worry about accidentally damaging surrounding plants while fertilizing your lawn. This is particularly nice when using a broadcast spreader.

Application Tips

  • Mow your lawn before fertilizing.
  • Close the spreader hopper before adding the product.
  • Fill the hopper on a drive or walkway to avoid over-application, particularly important for herbicides and synthetic fertilizers which can burn your lawn.
  • Sweep up any product that falls on hard surfaces to avoid it washing into waterways.
  • If you accidentally dump Milorganite on your lawn, gather what you can then use a stiff broom is spread what remains.
  • Walk at a steady pace. You’re an important part of the distribution rate equation. The slower you walk the more product will be distributed, and less is distributed when you walk faster. That’s one of the reasons application rates can vary.
  • Drop spreaders: overlap wheel marks to ensure even coverage and avoid unfertilized stripes.
  • First, apply a header strip—two overlapping passes—of fertilizer around the perimeter of your lawn for easier turns.
  • Start along the longest edge of your lawn.
  • Close the spreader off when making turns to avoid uneven application.
  • After a turn, start walking before opening the spreader.
  • Apply 50% of the product in one direction and the other 50% in the opposite direction to help ensure even coverage. Do this by reducing your spreader setting by half.
  • Avoid spreading the product on windy days so the product stays where you want it.
  • Clean your spreader after each use.
  • Follow manufacturers’ guidelines for lubricating, cleaning, and storing your spreader.

Bag of Milorganite fertilizer in a spreader in the lawn.

Six (or less) easy steps to calibrating your spreader

We have spreader settings for a number of popular spreaders on our website. If your spreader isn’t listed, it’ll only a few minutes using six easy steps, to calibrate your spreader. Your target is to cover approximately 500 sq ft of lawn with 8 lbs. of Milorganite.

Here’s how:

  1. Set your spreader so that it’s ¾ open when engaged. If, for example, the spreader is calibrated 1 to 20, set it at 15.
  2. Place eight pounds of Milorganite into the spreader’s hopper. This is about one-fifth bag, or 8 lbs., of Milorganite, which is equivalent to 24 cups. (1 lb of Milorganite is approximately 3 cups.)
  3. Start on a straight edge of your lawn. This will make it easier to later calculate the coverage area (length x width). Fertilize your lawn according to the application tips, paying particular attention to overlapping properly and walking at a steady pace. Continue until the spreader is empty. Leave the spreader where it is when it runs out of Milorganite.
  4. Measure the area (length x width) of the lawn you are fertilizing. More or less, you should have covered about 500 sq ft. If so, congratulations! You’re set! Your spreader is calibrated for applying Milorganite. You can skip steps 5 and 6. Continue to fertilize your lawn with Milorganite.   If you covered an area significantly more or less, move on to steps 5 and 6.
  5. If you covered much more than 500 sq ft, increase the amount of product distributed by your spreader. This is going to take some guesswork as to what setting to use. (Sorry, it’s part of the process.) Repeat steps 2–4 on an unfertilized area of your lawn and again calculate the square footage covered.
  6.  If you covered much less than 500 sq ft, decrease the amount of product distributed by your spreader. This is also going to take a bit of guesswork. Repeat steps 2–4 on an unfertilized area of your lawn and again calculate the square footage covered.

After you calibrated your spreader for fertilizing with Milorganite, write down the setting, and don’t lose it! You shouldn’t have to calibrate your spreader again.

How to calibrate your spreader