Getting your lawn looking right is a lot easier once you figure out agri-fab spreader settings compared to scotts, especially since most bags of fertilizer or grass seed you pick up at the local hardware store only give you the numbers for the Scotts brand. It's a common frustration. You're standing there in the middle of your driveway, bag of "Turf Builder" in one hand and your trusty Agri-Fab tow-behind in the other, only to realize the chart on the back of the bag doesn't mention Agri-Fab at all.
It doesn't mean your spreader is useless—far from it. Agri-Fab makes some of the sturdiest spreaders for the money, but their calibration scale is just different from what Scotts uses. While Scotts often uses a scale that goes up to 15 or more, many Agri-Fab models use a smaller numerical range or a completely different flow rate. If you just guess and wing it, you'll either end up with a lawn that's half-starved or, even worse, stripes of burnt yellow grass because you put down way too much nitrogen.
Why the numbers don't match up
The main reason you can't just swap the numbers one-to-one is the design of the hopper hole and the speed of the agitator. Scotts spreaders are built with a specific "flow rate" in mind that matches their own product pellets. Agri-Fab, being an independent manufacturer, uses its own proprietary settings. Generally speaking, an Agri-Fab spreader's opening at a setting of "5" is going to be quite different from a Scotts spreader at a "5."
Another factor is the distribution pattern. Scotts spreaders often have a "EdgeGuard" feature or specific shielding that changes how the product hits the spinner. Agri-Fab spreaders, especially the larger tow-behind versions, are designed to cover a wider swath of ground, often with a more aggressive throw. Because they cover more ground per pass, the rate at which the material leaves the hopper has to be adjusted to ensure even coverage.
The rough conversion rule of thumb
If you're in a hurry and need a starting point, there's a general rule of thumb many lawn enthusiasts use. It isn't perfect, but it gets you in the ballpark. For most broadcast spreaders, the agri-fab spreader settings compared to scotts usually involve a bit of math.
A common conversion is to take the Scotts broadcast setting and reduce it by about 20% to 25% to find your Agri-Fab starting point. For example, if the bag calls for a Scotts setting of 5, you might start your Agri-Fab around a 3.5 or 4. If the Scotts setting is a 10, the Agri-Fab might be closer to a 7 or 8.
However, this isn't a hard science. Every material has a different density. Grass seed is light and fluffy, while pelletized lime is heavy and dense. They won't flow through the same hole at the same speed. That's why relying solely on a conversion chart can sometimes lead to an empty hopper halfway through the yard—or a half-full hopper when you thought you were finished.
A quick comparison reference
To give you a better visual of how these usually shake out, here's a loose comparison for standard fertilizer:
- Scotts Setting 2 -> Agri-Fab Setting 1.5
- Scotts Setting 3 -> Agri-Fab Setting 2
- Scotts Setting 5 -> Agri-Fab Setting 3.5
- Scotts Setting 8 -> Agri-Fab Setting 5
- Scotts Setting 12 -> Agri-Fab Setting 7.5
Again, use these as a starting point only. It's always better to start a little too light and have to go over the lawn twice than to dump everything in one pass and ruin your soil.
The 100 square foot test
If you want to be precise—and let's be honest, fertilizer isn't cheap these days—you should probably do a quick calibration test. This sounds like a chore, but it only takes about ten minutes and saves a lot of headache.
First, measure out a 10-foot by 10-foot area on a clean part of your driveway or a tarp (100 square feet). Look at the bag of product to see how many pounds it's supposed to cover. If a 30-pound bag covers 15,000 square feet, you should be putting down roughly 0.2 pounds per 100 square feet.
Put a small, known amount of fertilizer in your Agri-Fab spreader, set it to what you think is the right number, and walk that 100-square-foot area at your normal pace. If you've put down way too much or the hopper didn't seem to drop anything at all, you know exactly how to adjust the dial before you hit the actual grass.
Factors that change your settings
Even if you have the "correct" conversion, a few variables can throw everything off. Your walking speed (or tractor speed) is the biggest one. Agri-Fab spreaders are ground-driven. The faster the wheels turn, the faster the spinner flings the material, but the flow from the hopper remains relatively constant based on gravity. If you're sprinting across the lawn, you're spreading the material thinner. If you're crawling, you're piling it on.
Humidity and product age
Believe it or not, the weather matters. If it's a humid morning, fertilizer can get "tacky" or clump together. This slows down the flow through the spreader hole. If you're using an old bag of seed that's been sitting in a damp garage, it might not flow as smoothly as a fresh, dry bag. When things aren't flowing well, you might need to bump your Agri-Fab setting up a half-notch to compensate.
The condition of your spreader
An old Agri-Fab that's seen five seasons of salt and fertilizer might have some corrosion around the discharge hole. Even a little bit of rust or crusty residue can change the diameter of the opening. It's always a good idea to make sure the sliding plate moves freely and opens all the way. If the plate is sticking, your agri-fab spreader settings compared to scotts won't mean much because the mechanical output is compromised.
Grass seed vs. Fertilizer settings
It's important to note that grass seed is a totally different beast. Because seed is so much lighter, it tends to bridge over the hole in the hopper. If you're looking at Scotts settings for seed, they are often much higher than fertilizer settings.
When using an Agri-Fab for seed, you usually want the setting to be wide enough that the seeds don't get stuck, but not so wide that you're essentially "pouring" the seed out. For fine fescue or bluegrass, a lower setting (around 3 or 4) is usually plenty. For larger seeds like tall fescue or rye, you might need to jump up to a 5 or 6.
Maintenance for consistent spreading
If you want your settings to remain accurate year after year, you've got to clean the thing. Fertilizer is incredibly corrosive. If you leave it sitting in the hopper or on the gears, it will eat away at the metal and plastic.
After every use, hose out the spreader thoroughly. Once it's dry, I like to hit the moving parts—especially the axle and the gearbox—with a little bit of silicone spray or light oil. This ensures that when you set the dial to "4" next spring, it actually opens to the same width it did this year. A well-maintained Agri-Fab can last a decade, making the time spent learning the conversion settings well worth it.
The bottom line on settings
At the end of the day, the numbers on the dial are just a guide. Whether you're using a push model or a tow-behind, the goal is even coverage without over-applying. The comparison between Agri-Fab and Scotts isn't an exact science because of the mechanical differences between the brands.
Don't be afraid to experiment a little. Start with a conservative setting—maybe a 3 or 4 for most standard fertilizers—and see how the coverage looks on a single pass. It's much easier to go back over the lawn in a perpendicular pattern to finish off a bag than it is to try and fix a lawn that's been over-fertilized. Once you find that "sweet spot" for your specific walking or driving speed, write it down on the inside of the hopper with a permanent marker. That way, next season, you won't have to go through the whole "agri-fab vs scotts" mental math again.