Organic Lawn Fertilizer: How to Grow Chemical-Free Grass

side view of healthy soil and grass

Would you rather take a chemical-free approach to fertilizing your lawn? It’s not as hard as you think, so stick around as we learn how to keep your lawn green the natural way.

An organic primer

Before we get into the details of how to green up your lawn organically, we wanted to give a few points on the organic philosophy and define a few terms. 

The term “organic” is used in many different ways. For example, the U.S. Department of Agriculture has an organic certification program for food. In this article, we will use the term “organic” in the sense of holistic and formed without synthetic inputs. 

The words “synthetic” and “chemical” are a little more straightforward. When we say synthetic or chemical, we mean man-made or formed by industrial processes.

Before we dive into how to green your turf, take a moment to learn more about the differences between these two approaches to lawn care.

illustration depicting organic fertilizer and synthetic fertilizer

An organic approach…

  • Is a holistic approach
  • Centers around soil health: “Feed the Soil”
  • Is a long-term solution
  • Considers the impact on humans, local communities, and ecosystems
  • Stresses the local economy rather than the global economy
  • Focuses on the small-scale rather than the large-scale
  • Aims for sustainability
  • Lets nature do the work
  • Inputs are from the Earth
  • Increases biodiversity

A synthetic approach…

  • Focuses on yields and efficiency 
  • Focuses on plant health: “Feed the Plant”
  • Is a short-term solution    
  • Stresses the global economy rather than the local economy
  • Focuses on large-scale production
  • Relies on man-made processes
  • May have a heavier dependence on fossil fuels and industrial inputs
  • Decreases biodiversity

Organic fertilizer vs. chemical fertilizers

Organic and chemical fertilizers are composed of the same macronutrients – nitrogen (N), phosphorus (P), and potassium (K) but are derived from different sources.

Organic Fertilizer Synthetic Fertilizers
Made from grass, leaves, plant waste, vegetables, fruits, other food waste, animal excrement, seaweed, blood, bone meal, kelp, fish, paper products and cardboard, or shredded wood productsPhosphorus and potassium are mined from minerals in the Earth. The nitrogen component in fertilizers is created via the Haber-Bosch process. In this process, one atom of nitrogen gas (N₂) is fixed to three atoms of hydrogen (3H₂) to form ammonia (NH₃). The ammonia is converted to a usable form (nitrate and nitrite) by the microbes in the soil.
Nutrients are released into the soil over time as the microorganisms break down the fertilizer or compost material. Released into the soil with regular watering.

The Haber-Bosch process

The Haber-Bosch process is named after the two German scientists — Fritz Haber and Carl Bosch — who developed a method to produce ammonia from nitrogen gas and scale the product commercially. Both scientists received the Nobel prize for their contributions. The Haber-Bosch process is credited with helping to feed the world in the 20th century and usher in the age of modern agriculture.

Critics of synthetic fertilizers point out that the ammonia (NH₃) in fertilizers can be toxic to fish and detrimental to water systems when residues run off into nearby waterways. In addition, the Haber-Bosch process relies on a large amount of energy and fossil fuels and emits large amounts of carbon dioxide, which critics say may be unsustainable long term.

Pros and cons of using organic lawn fertilizer


✓ Protects water systems
✓ Homemade compost diverts waste from the landfill
✓ Homemade compost doesn’t cost anything
✓ Enriches soil 
✓ No risk of burning the plants
✓ Compost improves soil structure 
✓ Compost adds organic matter and nutrients
✓ Compost is naturally “slow-release,” thereby providing nutrients over a long period   


✗ Slower greening of the lawn
✗ Store-bought organic varieties may be more expensive than synthetic fertilizers
✗ Generally have much lower N-P-K values 

Timing it right

If you’re looking to take the first step into organic lawn care but want to keep things simple, start by leaving the grass clippings on the lawn after each mow. There are no fertilization schedules to worry about, and it’s free. According to the University of Minnesota Extension, a year’s worth of grass clippings left on the lawn is equal to one synthetic fertilizer treatment.

There are a few different approaches for when to fertilize your lawn. 

The Ultra-Specific Approach

In short, you’ll have to look at a lawn maintenance calendar for your grass type in your state, such as this Texas A&M St. Augustinegrass calendar or this University of Nebraska – Lincoln Management Calendar for Cool-Season Lawns. Contact the Cooperative Extension Service in your state for a similar calendar (or search on their website). This will give you an ultra-specific schedule based on your climate and grass type.

The Grass Type Approach

If you want to keep it simple, plan to do two applications per year. A good rule of thumb, if you have warm-season grass, is to fertilize in the late spring and again in the late summer/early fall. If you are in a cool-season area, fertilize in early fall and again in late spring after green-up.

infographic showing the cool and warm season grasses on the US map, along with the transitional zone

The Three-Holiday Approach

This is another way experts try to keep their advice simple and easy to remember. Fertilize your lawn three times: once near Memorial Day (spring), Independence Day (early summer), and Labor Day (late summer). This approach works better for warm-season grasses. Many cool-season grasses go dormant during the summer, and this is not the optimal time to fertilize them.

It’s always a good idea to check with a local expert or lawn care professional to verify what works in your area for your grass type.

How to use organic fertilizer on your lawn

  •  Get a soil test. 

A few weeks before your first mow, do a soil test. Take this to your local Cooperative Extension Office, or do an at-home soil test. 

  • Measure the space.

Walk around the lawn with a measuring tape, or count your paces, to measure the lawn in square feet. You’ll need this number to determine how much fertilizer you need.

  • Mow the lawn.

Just this once, attach the bag to the mower and collect the grass clippings. This will help the fertilizer to have better contact with the soil.

  • Purchase and spread the fertilizer.

If you haven’t done a soil test, use your Extension Service’s lawn calendar for fertilizer advice, or buy a bag that is branded as an organic fertilizer for lawns. Apply according to the package instructions. Use a spreader to apply.

  • Water it in.

Read the instructions on the fertilizer, but most fertilizers like to be watered in. Be careful not to over-water.

Fertilizer facts

According to one fertilizer company, lawn fertilizer mixes should have around a 3-1-2 ratio of N-P-K. This isn’t a hard-and-fast rule, but the ratio for an organic lawn care fertilizer should come close. (Note: This doesn’t mean it will say “3-1-2” on the bag, but that is the ratio you will generally see for lawn fertilizer.) 

Nitrogen – helps to produce a nice, green lawn 

Phosphate – not a key nutrient for lawns; you can go without if your soil levels are good

Potassium – used for root system development

Organic lawn care tips

Aeration: If you are fertilizing twice per year using the “Grass Type Approach,” this is also a prime time to aerate. Aeration helps more water, fertilizer, and air (hence the name) to reach the soil.

Mow high: Mowing at the highest recommended height for your grass type is better for the lawn. A longer lawn is more inhospitable for weeds.

Water: Water the lawn deeply but less frequently. If you’re unsure how much water the sprinkler system is putting on the lawn, use a simple “tuna can audit” to measure. Most lawns can go five to eight days between waterings, depending on the soil type. Look for signs of drought in the lawn before you water again. This encourages roots to grow deep into the soil.

Topdressing: Topdressing is simply adding organic materials on top of an established lawn to help improve the soil composition. Compost, a natural lawn food and soil amendment extraordinaire, is the favored choice. Sand is another popular choice; it depends on what your soil needs. When you overseed with new grass seeds, it is common to topdress the soil with compost. This gives the seed a layer of soil in which to rest and improves soil composition.

Liquid vs. Granular: Fish emulsion and kelp meal are often sold as liquid fertilizer, but the majority of brands sell their fertilizer as granules.


1. What are a few brand names to look for?

Popular brand names include:

✓ Milorganite 
✓ Espoma
✓ Jobe’s 
✓ Kellogg Garden Organics
✓ Purely Organic 
✓ EcoScraps

Remember, you can visit landscaping supply companies to purchase large amounts of compost, wood chips, and other organic materials that help to build your soil. You will almost certainly save money purchasing from a landscape supplier if you are buying large amounts of compost.

2. What are other tips to build my soil?

  • –If you have horse farms nearby, these homeowners may let you pick up truckloads of that rich manure/straw combination for free. Once this breaks down, this is a rich compost material — a great natural lawn fertilizer.

  • Earthworms are one of nature’s best soil builders. They aerate, leave castings that increase microbial activity, reduce compaction, and help churn the soil, to name a few. While it is not recommended, in some cases, to purchase earthworms, organic matter is a food source for them (including manure). The adage “If you build it, they will come,” applies. Another benefit of using organic methods on the lawn is that you are not using pesticides, which can be toxic to earthworm populations.

    Organic lawn fertilizer builds a healthy lawn from the ground up

    If you had to sum up the organic approach to lawn fertilizing, you could say that healthy soils beget healthy lawns. Organic lawn fertilizers nourish the soil that will nourish your grass. Remember that you can fertilize two, three, or four times per year, or search for your Extension Office’s grass-specific lawn maintenance calendar. If you’re patient enough to let mother nature work on her timetable, the results will be well worth the wait.

    If your thumb is more gray than green, contact a local lawn care pro to help your lawn green-up nature’s way.

    Main Photo Credit: Natural Resources Conservation Service Soil Health Campaign | Flickr | CC BY 2.0

    Rachel Abrams

    Born and raised in Gainesville, Florida, Rachel Abrams studied creative writing at the University of Virginia. She enjoys volunteering at her neighborhood community garden and growing herbs in her New York City apartment.