What Does Fertilizer Do For Grass?

Simply put: Fertilizer helps grass blades grow long and strong

Contemporary Craftsman-style home
Photo: Pella Windows and Doors
Contemporary Craftsman-style home
Photo: Pella Windows and Doors
Melissa Graham
Written by Melissa Graham
Contributing Writer
Updated February 6, 2024

Highlights

  • Fertilizer is a solution made of nutrients to help promote a healthy lawn. 

  • There are many benefits to applying fertilizer, including greener, more resilient grass and more lawn coverage. 

  • Different types of fertilizer include liquid, granular, synthetic, and organic. 

  • A soil test can help you determine which type of fertilizer is best for your yard.

Get quotes from up to 3 pros!
Enter a zip below and get matched to top-rated pros near you.

Most people know that fertilizer is a helpful tool for growing grass. But what exactly does fertilizer do for your grass?

From understanding NPK ratios to identifying the different types of fertilizer, we’ll break down the nuances of lawn fertilizer so you can understand how it works and which type is best for your lawn. You don’t need a chemistry degree to understand the lush landscape of fertilizers—only an eagerness to learn, a pair of gardening gloves, and advice from a professional lawn fertilization service to get started.

Angi Tip
When working with lawn fertilizer and other chemicals, take measures to prevent the products from contacting your skin and eyes. Be sure to wear protective gear like gloves and a dust mask to stay safe.
Kaitlyn Pacheco
Content Editor, Angi

What is Fertilizer?

Plant illustration and description on how nitrogen, potassium, and phosphorus relate to plant health

Fertilizer is a product made of nutrients to help grow and sustain healthy grass. It comprises three main elements: nitrogen, phosphorus, and potassium. Nitrogen helps aid photosynthesis and is partly responsible for the vibrant green color in grass blades. Phosphorus helps with root development and the formation of strong, sturdy grass that can withstand extreme weather conditions. Potassium increases your yard’s resilience to diseases and assists with water retention.

Most fertilizers have “NPK” ratios that let homeowners and landscapers know what percent of nitrogen, phosphorus, and potassium are in each solution. For example, a bag of fertilizer with 10-10-10 on the front indicates that it has 10% of the three elements in its makeup. The correct ratio for your lawn depends on your soil needs, which can be determined by conducting a soil test. So, if a soil test reveals that your lawn is low on nitrogen, you may need to find a bag of fertilizer with more nitrogen.

What Are the Benefits of Fertilizer?

woman holding fertilizer in her hands
Photo: Deidre / Adobe Stock

There are hardly any downsides to using fertilizer, as long as you don’t overdo it and risk overfertilization. Luckily, most fertilizers come with detailed instructions on how to apply them and how often to use them. When you use fertilizer on your grass, it often:

  • Helps control weeds 

  • Improves color 

  • Enhances growth 

  • Develops strong roots 

  • Increases resilience 

  • Improves overall health

If you decide to utilize fertilizer, it’s important to follow application instructions and safety precautions. When working with lawn fertilizer and other chemicals, prevent the products from contacting your skin and eyes. Be sure to wear protective gear like gloves and a dust mask to stay safe.

Types of Fertilizer

man sprinkling fertilizer on lawn
Photo: ImagESine / Adobe Stock

Just like there are several types of grass, different types of fertilizer that work best depending on your lawn’s specific needs. The best fertilizer for your particular lawn depends on several factors, including the type of grass, the climate where you live, what your soil needs, and what results you’re looking for. A soil test will determine what nutrients your soil lacks and what specific solution your lawn can benefit from best. Once you’ve completed a soil test, you can consult a local lawn fertilization expert about how to pick a fertilizer, when to apply it, and how often to treat the lawn. 

Liquid Fertilizer

Some liquid fertilizers come ready to apply in spray bottles, while others must be diluted with water and hooked up to a garden hose. This type of application is less tedious than granular fertilizer, but that can also mean that the coverage is more patchy and that some areas receive more fertilizer than others. However, this fertilizer works well for delivering quicker results. 

Granular Fertilizer 

Granular fertilizer is made up of tiny granules that can be spread over your lawn with a spreading tool. It’s one of the more common types of lawn fertilizer. A majority of granular fertilizers are slow-release, so they add nutrients to your soil over time instead of instantly. Although this type of fertilizer can take longer to show improvements, it provides more even coverage than liquid and has longer-lasting results. 

Synthetic Fertilizer

Synthetic fertilizer is made of manufactured nutrients that produce faster improvements and come at a lower cost than other types of fertilizer, such as organic. However, pet owners may want to steer clear of synthetic fertilizer because it’s often toxic to pets and could put them in danger if ingested. 

Organic Fertilizer

This type of fertilizer comes from natural materials like manure, seaweed, compost, and other nutrients. It’s more environmentally friendly than synthetic fertilizer but comes at a higher cost. If you want long-lasting results and safe ingredients that boost the presence of microorganisms such as worms and helpful bacteria, organic fertilizer may be the best choice for you.

When to Apply Fertilizer to Your Lawn

Similar to how you plan the perfect season to plant a rose bush, choosing the right time of year to fertilize your grass for best results is important. It also depends on the type of grass and what region of the country you live in since some areas experience more severe seasons than others. 

Warm Season Grasses 

In the Southern region of the U.S., warm-season grasses include Bermuda, centipede, St. Augustine, Kikuyu, and Zoysia. These varieties have a thick lawn cover that thrives in—you guessed it—warmer temperatures and are tough enough to withstand the heat. Since warm-season grasses have a peak growing period of late spring and summer, it’s best to apply fertilizer in the early spring or late fall when temperatures even out. 

Cool Season Grasses

Northern parts of the U.S. have more cool-season grasses, such as Kentucky bluegrass, ryegrass, and tall and fine fescues. These grass varieties prefer lower temperatures and typically experience the most growth during the early spring and early fall. You’ll want to apply fertilizer to cool-season grass more heavily in the fall and lighter in the spring to ensure the most success. 

Signs Your Lawn Needs Fertilizer

Although your yard can’t tell you in words that it needs added nutrients, it can communicate physically that it needs fertilizer. One or more of the following signs may indicate that it’s time to incorporate fertilizer in your lawn maintenance schedule

  • Thinning grass

  • Loss of color 

  • Rapid weed growth 

  • Slow growth 

  • Too much moss 

If testing your soil, finding the right fertilizer, and applying it involves more time than you have to dedicate to your grass, you can reach out to a local lawn fertilization service to do it for you. They can take a closer look at your lawn and develop a treatment plan to get your grass in tip-top shape in no time.

Need professional help with your project?
Get quotes from top-rated pros.
Learn more about our contributor
Melissa Graham
Written by Melissa Graham
Contributing Writer
Melissa has spent over ten years writing about home design, style, and DIYs for regional and national publications.
Melissa has spent over ten years writing about home design, style, and DIYs for regional and national publications.
The homeowners guide to Lawn Fertilization & Treatment
From average costs to expert advice, get all the answers you need to get your job done.