We Tested Organic Lawn Fertilizers—These 6 Work Best

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Organic fertilizers for lawn grass play a key role in building a thicker, greener lawn without relying on synthetic chemicals, and they’re especially appealing if you’re looking to improve soil health over time. To find the most effective options, we tested six popular fertilizers on a St. Augustine lawn in Florida, applying each to separate sections and tracking changes in color, thickness, and overall growth over several weeks.

Across the board, the granular fertilizers delivered the most noticeable results, producing deeper green color and fuller turf compared to untreated areas. Our top pick, the Lawnbox Grass Genie 10-0-6 from Lawn Box, stood out for how quickly it improved both color and density without any signs of burning or uneven growth. While most of the granular formulas performed similarly, subtle differences in application, consistency, and long-term results helped separate the best from the rest. The only outlier was the liquid kelp formula, which didn’t give us the same quick visible improvements during testing. (This is likely because it contained zero nitrogen—which St Augustine grass typically wants most—so we can’t judge too harshly there). 

Choosing a high-quality organic grass fertilizer matters because it directly impacts not just how your lawn looks, but how well it holds up over time. Ingredients, nutrient balance, and release speed all play a role in achieving consistent growth without damaging your grass. Ahead, you’ll find our detailed reviews of each product, including how they performed in real-world testing and where each one stands out.

1. BEST OVERALL: Lawnbox Grass Genie 10-0-6
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2. BEST BANG FOR THE BUCK:  Richlawn 5-3-2 All-Purpose Lawn Fertilizer
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3. BEST PREMIUM: Down to Earth Bio-Turf 8-3-5 All Natural Fertilizer
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4. BEST FOR BEGINNERS: Scotts Natural Lawn Food
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5. BEST YEAR-ROUND: Espoma Turf Tone All Season Lawn Food
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6. BEST LIQUID: GS Plant Foods Organic Liquid Kelp Seaweed Fertilizer
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Quick Comparison: Best Organic Lawn Fertilizers

Before You Buy Organic Lawn Fertilizer

Choosing the best organic grass fertilizer requires an understanding of the lawn’s current condition. Is it generally healthy and simply needs regular feeding? Or does it display a nutrient deficiency of some kind? The type of grass will also determine which fertilizer to use. For example, fertilizers for St. Augustine grass will deliver different levels of nutrients than those for Bermuda grass. 

Before buying and applying fertilizer, it’s smart to perform a soil test to identify your soil’s pH and nutrient content. These results will help you determine which organic fertilizer to apply as part of your personal DIY lawn care program. 

Our Top Picks

Each organic lawn treatment on our list of top picks is made from quality ingredients and provides essential nutrients for growing new grass or helping an existing lawn thrive. 

The Grass Genie 10-0-6 earned its top spot by delivering the most noticeable improvement in both color and thickness during testing. This 100 percent organic formula is designed for spring applications, combining quick- and slow-release nitrogen to jump-start growth while continuing to feed the lawn for several weeks. It also includes humic acid to support soil health, which can help improve nutrient absorption over time. The formula is free from animal byproducts and biosolids, making it a cleaner option for homeowners who want a more natural approach to lawn care.

In side-by-side testing, we could clearly see that this fertilizer produced the deepest green color and the fullest turf after about a month, which clearly outperformed the other options. Application was straightforward, and like the other granular formulas, it spread evenly without any issues. The only real downside we found is that it’s more of a seasonal product, best suited for spring use rather than year-round feeding. Still, for a strong early-season boost, it stood out as the most effective option overall.

Richlawn Organic 5-3-2 is a straightforward, budget-friendly option that still delivers solid results. This OMRI-listed formula is made from 100 percent organic ingredients, with a heavy focus on slow-release nitrogen to provide steady feeding over time. It’s widely used by turf professionals on golf courses and commercial properties, but we found it just as easy to apply at home. The non-burning formula is safe for use on new or established lawns, even in warmer conditions, and we also liked that it can be used on gardens and landscaping beds, too.

In testing, it performed right in line with the other granular fertilizers, producing noticeably greener and slightly thicker grass after a few weeks. Application was simple and consistent, with no issues during spreading. Where it really stands out is value—it’s one of the most affordable options in the lineup without sacrificing performance. While it doesn’t offer any standout extras compared to higher-end blends, we found it to be a reliable, no-frills choice that gets the job done.

Down To Earth Bio-Turf 8-3-5 is a well-rounded organic fertilizer that focuses on both visible growth and long-term lawn health. This granular formula is rich in nitrogen to promote early-season greening, while added potassium helps the grass better handle stress from heat and drought. It’s also designed to support deeper root development, which we found helpful for encouraging thicker and healthier growth over time. The packaging stands out as well, using a thick paper bag instead of plastic, which feels more in line with its natural approach.

In testing, this nitrogen-rich lawn fertilizer​ performed just as well as the other top granular options, producing a noticeably greener and fuller lawn after about a month. The granules were easy to spread evenly, making application quick and hassle-free. While it doesn’t dramatically outperform similar formulas, we think it’s a reliable choice with a strong nutrient profile and a more eco-conscious packaging.

Scotts Natural Lawn Food is a widely available option that offers a simple, no-fuss way to maintain a healthy lawn throughout the growing season. With an 11-2-2 NPK ratio, it provides a balanced mix of nutrients to support steady growth, root development, and overall lawn resilience. The formula is made from natural ingredients like bone meal and blood meal and is suitable for all grass types. Scotts recommends applying it every 6 to 8 weeks, making it a practical choice for ongoing feeding.

When we tested it, it performed pretty similarly to the other granular fertilizers, giving greener, thicker grass within a few weeks. The large bag size and consistent granules made it easy for us to apply evenly using a standard spreader. Coverage is somewhat limited for the bag size, so larger lawns may require multiple bags over the season. Still, its accessibility and ease of use make it a solid pick, especially for homeowners new to organic lawn care.

Espoma Turf-Tone All Season Lawn Food is designed to be a reliable, year-round option for maintaining healthy grass across multiple growing conditions. Its 9-0-1 formula relies on slow-release nitrogen to promote steady growth and long-lasting color, while the brand’s Bio-tone blend is intended to support soil health and root development. It’s safe for use on a wide range of grass types, including St. Augustine and zoysia, and is made without sludges or harsh chemicals, making it a solid choice for households with kids and pets.

It performed similarly to the other granular fertilizers we tested, producing a greener, thicker lawn after roughly 2 weeks. The granules spread easily and evenly, making application straightforward with a standard spreader. While we didn’t feel like it stood out dramatically compared to the top performer, its all-season versatility makes it a dependable option for ongoing lawn care rather than a one-time boost.

GS Plant Foods Organic Liquid Kelp Fertilizer takes a different approach from the granular options, using seaweed extract (Ascophyllum nodosum) to support overall plant health rather than delivering a heavy dose of nutrients. With a very low NPK ratio (0-0-1), it’s better suited as a supplement or soil conditioner than a primary lawn fertilizer. The liquid formula must be diluted with water and applied using a sprayer, which adds an extra step compared to traditional spread-and-go products. On the plus side, it has little to no odor and can be used across a wide range of plants, from lawns to garden beds and even houseplants.

On our test lawn, we didn’t notice this organic liquid lawn fertilizer​ producing the same instant improvement in lawn color or thickness as the granular fertilizers, especially on St. Augustine grass, which tends to respond best to nitrogen-rich formulas. Our treated patch stayed sparse and less green compared to the others. However, its versatility makes it a useful option for gardeners looking to support overall plant health rather than maximize lawn growth.

Or, DIY Your Own Organic Lawn Fertilizer

While there are plenty of commercially produced organic lawn fertilizers on the market, it’s also possible to make a homemade fertilizer for lawns that delivers excellent results. A good fertilizer for grass should be about 50 percent organic matter and plant-based material, such as composted manure, garden clippings, decomposed leaves, sphagnum peat moss, sawdust, wood chips, or even seaweed. The other half of the fertilizer blend should contain slow-release sources of nitrogen such as blood meal, fish meal, cottonseed meal, feather meal, kelp meal, or soybean meal. 

Once you have gathered the necessary materials for the homemade lawn fertilizer mix, start blending them in equal parts in a bucket or large container. Make sure to mix them thoroughly so it’s easy to apply everything evenly on your lawn. 

Jump to Our Top Picks

FAQs

The best organic fertilizer can help keep lawns vigorous and healthy. For more information on using fertilizers, check out the answers to these frequently asked questions.

Q. What is the best N-P-K ratio for lawn fertilizer?

This really depends on your lawn. Before purchasing a fertilizer, buy an over-the-counter soil test kit or send a soil sample to your county’s Cooperative Extension Service for analysis. Use the soil test results to guide lawn fertilizer choice and application.

Q. When should I apply fertilizer to my lawn?

Grass will take up a good organic fertilizer for lawn care throughout the growing season. The best times to apply it are when active growth begins in spring and again in midsummer, as well as prior to winter, to increase hardiness.

Q. How often should I apply organic fertilizer to my lawn?

The frequency with which you should apply organic fertilizer to your lawn depends on the product you’re using and the conditions of the soil. Generally speaking, however, you will need to fertilize anywhere from a few times a month to once every few months. To get the best results for your lawn, perform a soil test and follow the manufacturer’s instructions. 

Q. Can you overfertilize your lawn with organic fertilizer?

No. Generally speaking, it’s unlikely you will cause fertilizer burn with an organic law care fertilizer. However, applying excess product is bad for the environment and your wallet.

Q. Is organic fertilizer safe for pets and children?

Yes, most organic fertilizers are safe for pets and children once applied as directed, though it’s still best to let the product settle or water it in first.

The post We Tested Organic Lawn Fertilizers—These 6 Work Best appeared first on Bob Vila.

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