If you’re in the lawn care aisle trying to decide which bag of fertilizer to buy, don’t be in a hurry.
It’s confusing over there. Also, if you wanted to do math problems, you would have taken way more algebra classes, right?
A bag of fertilizer might say 10-10-10. Or 24-8-16. Or just about any combination of three numbers.
Here's what it's all about.
What do the three numbers on fertilizer mean?
The three numbers on lawn fertilizer represent the percentages of nitrogen, phosphorus, and potassium (NPK).
It’s called the NPK rating.
The first number (N) is the amount of nitrogen, the second number (P) is the amount of phosphorus, and the third number is the amount of potassium (K) in the fertilizer. These lawn fertilizer numbers are significant because each nutrient helps your lawn differently.
Read on to learn more.
All lawn fertilizer labels have three numbers that designate the combination of ingredients. The first number is the amount of nitrogen, the second is the amount of phosphorus, and the third is the amount of potassium.
Different fertilizer formulas, also called NPK ratings, treat different lawn needs.
Let’s take a look at what each ingredient is up to out there:
Nitrogen gives you that nice green grass that you love and hope makes your neighbor jealous.
Nitrogen promotes healthy, vibrant green grass by stimulating chlorophyll production, essential for photosynthesis and giving the grass its color.
Thank Nitrogen for that beautiful green color.
Phosphorus encourages strong roots. This isn’t as visible to you as those beautiful green grass blades, but strong roots are important for a healthy lawn.
Phosphorus helps grass establish itself by anchoring roots into the soil, so this ingredient in the NPK rating is especially important for new lawns.
Phosphorus also helps grass grow by supporting energy transfer throughout the plant.
Potassium does all kinds of great stuff, strengthening the cell walls of grass blades, improving your lawn’s tolerance to stress and promoting good root development.
“Cell walls” sounds like a lesson from science class, and this is pretty sciencey.
Potassium helps grass produce cellulose, which makes cell walls stronger and more rigid.
Why should you care if your grass has strong cell walls? They help keep those grass blades standing up nice and straight.
Potassium also helps your lawn withstand stresses like drought, heat, cold, and disease.
It helps grass survive weather changes, too, like hot summers and cold winters. Potassium helps grass take up water and nutrients from the soil.
Potassium is super busy out there.
Is there a preferred NPK ratio in Minneapolis, MN, and Eau Claire, WI?
Get ready for some extra numbers. A significant factor is how many pounds of these nutrients your lawn needs yearly, says Jake Jacobson, lawn care operations manager at RainMaster Lawn Systems.
“A lawn in our area requires 4-5 pounds of nitrogen for every 1,000 square feet, per season,” Jacobson says. “Nitrogen is the first letter in the NPK ratio and the most important. We typically use a formula like 25-0-4 or 18-0-4.”
RainMaster lawn specialists apply about one pound of nitrogen per 1,000 square feet of lawn at each of five lawn care visits throughout the season, he says, to reach that yearly goal of 4-5 pounds.
Hold on a minute. Those ratios Jacobson just gave have zeros in the middle. 25-0-4? 18-0-4?
What about phosphorus?
“We can only use phosphorus in our formulations on newly seeded lawns,” Jacobson says.
He says that state laws limit the use of phosphorus because it leaches into waterways, endangering the environment. The law makes an exception for newly seeded lawns because of the importance of phosphorus in helping new lawns get established.
Jacobson says that while a typical Minneapolis lawn might get a 25-0-4 NPK formula, those numbers change during the hot summer months.
”We tend to go lower in the summer months with the nitrogen number,” he says. When a lawn is heat stressed, it doesn’t need as much nitrogen, Jacobson says. Nitrogen encourages a lawn growth spurt, which causes it to go dormant in the heat, out of stress.
So, in the summer, RainMaster pros use a lower nitrogen formula of 18-0-4 versus the typical 25-0-4 the rest of the year.
New lawns get a different NPK number, too, Jacobson says.
Remember, he said phosphorus is allowed on new lawns. He uses a 16-12-10 ratio for them.
“Phosphorus promotes root growth and development, which is crucial in establishing new lawns,” he says.
Now that you know what the three numbers on lawn fertilizer mean, you might have a big new boost of confidence. Why not just do it yourself?
You absolutely could. But do you know how many bags of fertilizer you need? How do you calibrate your spreader so you know you’re applying it at the right rate? (You have a spreader, right?)
Here are a few things to keep in mind, beyond the NPK ratio for grass:
Too much fertilizer adds too much nitrogen and salt to the soil. It’s called fertilizer “burn,” and can kill your lawn.
So, beyond deciding which NPK rating to get, follow the proper lawn fertilizer schedule and the product directions.
Better yet, hire expert lawn care in Minneapolis, MN, to fertilize your lawn.
A professional lawn care service knows exactly how often to fertilize your lawn and what type to use, and they have the skills and knowledge to know what else your lawn needs to thrive.
We’re not saying it’s impossible to figure this all out. But is it really how you want to spend your weekend?
Beyond choosing your NPK ratio for grass, you must decide whether to use liquid or granular lawn fertilizer.
Liquid fertilizer is, well, liquid. It comes in a concentrated form and is mixed with water to create a solution of nutrients sprayed on your lawn.
Granular fertilizer is solid pellets of product spread over your lawn and then watered into the soil.
The basic nutrients in liquid lawn fertilizer are the same as in granular fertilizer — nitrogen, phosphorus and potassium — but they work a bit differently.
Liquid fertilizer delivers a quick dose of nutrients, while granular fertilizer offers a slow release of food for your lawn over time.
Always choose granular fertilizer for the best lawn care in Minnesota and Wisconsin. Yes, it costs more, but it breaks down slowly, giving you consistent benefits from fertilization.
Look for blends containing organic nutrients, which help give your lawn that beautiful, deep green color and help your soil.
You’ll get premium professional-grade formulations of granular fertilizer from RainMaster. Not every lawn fertilizer service offers this.
Once you have your lawn fertilizer numbers figured out, when should you apply the fertilizer?
The first fertilizer and weed control round should be done by Memorial Day. Three more applications should happen throughout the summer.
Don’t forget about fall fertilizing. That last boost of the year gives your lawn’s roots nutrients to grow nice and deep now, with some leftover for a healthy start — and greener grass — next spring.
Their skill and expertise are a big part of what you’re paying for when you hire lawn care services in Minneapolis.
That includes figuring out all the fertilization details so your lawn gets the nutrition it needs to thrive.
Here at RainMaster Lawn Systems, we take lawn fertilizing seriously. That’s why organic-based, granular fertilizer tops the list of all three of our lawn care programs.
We’re also serious about all the elements that bring out the best in fertilizer, from soil conditioner to proper pH levels.
Don’t waste your Saturday being frazzled in the fertilizer aisle. Let us make it easy.
Ready to treat your lawn to the best lawn fertilizer service with no worries about the complicated parts? Request a quote today! We’ll review your lawn care options together so you can make a great choice.