10 Best Organic Lawn Fertilizers 2025 in the United States

O.M. Scott & Sons Natural Grass Food is a natural fertilizer designed to nourish lawns for up to 10 weeks after a single application. Its nutrient sources come from nature, avoiding synthetic chemicals, which makes it a safer choice for households with kids and pets. It’s formulated to work well with all grass types and is easy to apply in granular form. You just spread it over your lawn and water immediately to activate the feeding process.

This fertilizer is compatible with most soil pH levels, fitting a variety of lawn conditions without causing harm. The nutrient release is gradual, lasting up to 10 weeks, so frequent reapplication is not necessary. One of the environmentally friendly features includes recyclable packaging and the absence of harmful additives, reducing impact on the ecosystem. The coverage of 2,000 sq. ft. per bag is suitable for medium-sized lawns, and the two-pack offers good value for consistent lawn care.

Although the product does not specify an exact N-P-K ratio, it provides essential nutrients to support healthy grass growth. Users seeking specific nutrient balances might find it less straightforward to compare with other fertilizers. Additionally, some may notice that results develop more gradually compared to synthetic options. This fertilizer is ideal for homeowners wanting a natural, easy-to-use solution for maintaining a healthy lawn without harsh chemicals.

The Sunday Green Machine Fertilizer is a liquid lawn fertilizer designed for easy at-home use, covering up to 10,000 square feet per two-pack. Its N-P-K ratio is 22-0-3, meaning it offers a high amount of nitrogen for promoting lush, green grass and some potassium, but no phosphorus. The nitrogen source is enhanced with natural ingredients like seaweed and iron, which support deeper root growth and overall lawn health, aligning well with organic lawn care principles. Application is simple and convenient—just attach the pouch and sprayer to your hose and spray your lawn, making it a good choice for those who want fast, straightforward feeding without messy granules or complicated spreaders.

The liquid form generally means nutrients are readily available for quicker absorption by the grass, but may require more frequent applications every 4 to 6 weeks, especially during active growing seasons. It is best suited for lawns with neutral to slightly acidic soil pH, which is typical for most grasses. The formula avoids harsh chemicals, which reduces environmental impact and supports a healthier lawn ecosystem. However, since it lacks phosphorus, it might not be the best choice if your soil needs phosphorus to improve root development or repair damaged areas.

Because it’s liquid and applied with water, runoff during heavy rain could be a concern if not applied carefully. Sunday Green Machine serves well homeowners seeking an easy-to-use, nitrogen-focused organic fertilizer that encourages greening and root health without synthetic additives. For those needing a more balanced nutrient profile or slower nutrient release, other alternatives might be more suitable.

The Milorganite All-Purpose Eco-Friendly Slow-Release Nitrogen 6-4-0 Fertilizer offers a convenient solution for those looking to enhance their lawns, flowers, and gardens organically. With an N-P-K ratio of 6-4-0, it primarily focuses on providing nitrogen, essential for robust plant growth. One standout feature is its eco-friendly nature, ensuring that it does not burn your lawn or plants even in extreme weather conditions, thanks to its low salt content. This makes it particularly beneficial for maintaining healthy foliage without the risk of damaging your greenery.

The slow-release formula is another significant advantage, as it provides nutrients for up to 8-10 weeks, reducing the frequency of application and ensuring a steady supply of nutrients over time. Additionally, the inclusion of organically complex iron helps in achieving a deep, vibrant green lawn without staining concrete surfaces, which is a common issue with some synthetic fertilizers. However, the fertilizer has a relatively low phosphorus content (4) and no potassium (0), which may not be ideal for all soil conditions or plant needs. It’s more suited to established lawns and plants rather than new growth which might need a more balanced nutrient mix.

The product covers up to 2,500 square feet, making it suitable for medium-sized lawns and gardens. Considering its broad application method and soil pH compatibility, it's a versatile choice for gardeners seeking sustainable and effective lawn care. Those requiring a higher potassium or phosphorus content might need to supplement this fertilizer with additional products.