Lawn Fertilizer Numbers Explained

Achieving and maintaining a vibrant, healthy lawn requires a proactive approach to care — and one key component is the proper application of lawn fertilizers. Fertilizers are crucial in providing essential nutrients that promote robust growth, lush greenery, and overall lawn health.

Understanding fertilizer numbers is fundamental to ensuring your efforts yield the desired results. Fertilizer bags often display three prominent numbers, known as the N-P-K ratio, which represents the percentage of essential nutrients nitrogen (N), phosphorus (P), and potassium (K) in the product. These numbers serve as a code to unlock the secret to effective lawn nutrition.

Role of Fertilizers in Maintaining a Healthy Lawn

Fertilizers act as nutritional supplements for your lawn, compensating for deficiencies in the soil and providing the necessary elements for robust growth. Each nutrient uniquely supports different aspects of plant development:

  • Nitrogen (N): Stimulates leaf and stem growth, enhancing the lawn's lush, green appearance.
  • Phosphorus (P): Facilitates strong root development, improving the overall stability and resilience of the grass.
  • Potassium (K): Contributes to disease resistance and overall stress tolerance, ensuring your lawn can withstand various environmental challenges.

A well-balanced fertilizer ensures these vital nutrients are supplied in the right proportions, fostering an environment conducive to optimal growth and vitality.

Fertilizer Labels and Numbers

Before delving into the specifics of reading fertilizer numbers, it's essential to familiarize yourself with the information presented on fertilizer labels. Besides the N-P-K ratio, labels may also indicate the presence of secondary nutrients and trace elements, further influencing your lawn's nutritional intake.

Decoding the Three Numbers on Fertilizer Bags

When you pick up a bag of fertilizer, you'll likely encounter three numbers prominently displayed on the packaging. These numbers represent the N-P-K ratio, providing crucial information about the nutrient composition of the fertilizer. Let's break down the significance of each number:

1. Nitrogen (N) — The First Number

Nitrogen is a primary nutrient responsible for stimulating vigorous leaf and stem growth. A higher first number indicates a greater percentage of nitrogen in the fertilizer — particularly important for promoting a lush, green lawn, making it essential for the early stages of plant development.

2. Phosphorus (P) — The Second Number

Phosphorus is vital for root development, flower and fruit production, and overall energy transfer within the plant. The second number in the N-P-K ratio denotes the percentage of phosphorus in the fertilizer. A balanced phosphorus level establishes a strong root system, ensuring your lawn is well-rooted and resilient.

3. Potassium (K) — The Third Number

Potassium is key to enhancing your lawn's stress tolerance and disease resistance. The third number in the N-P-K ratio signifies the percentage of potassium in the fertilizer. A higher potassium content is particularly beneficial during periods of environmental stress, such as drought or extreme temperatures.

The N-P-K Ratio and Its Significance

The N-P-K ratio numerically represents the percentage of nitrogen, phosphorus, and potassium in the fertilizer. For example, a fertilizer labeled "10-20-10" has a nitrogen content of 10%, phosphorus content of 20%, and potassium content of 10%.

Understanding the ratio is crucial because it helps tailor your fertilizer choice to your lawn's specific needs. Different stages of growth and various grass types may require varying nutrient levels. For instance, a balanced fertilizer with equal N-P-K values (e.g., 10-10-10) is suitable for general maintenance, while specialized formulations cater to specific growth phases or lawn conditions.

Additional Elements in Fertilizers and Their Roles

Additional Elements in Fertilizers

Beyond the primary N-P-K trio, fertilizers may contain secondary nutrients and trace elements, each contributing to the overall health of your lawn.

1. Secondary Nutrients

Secondary nutrients, including calcium, magnesium, and sulfur, are essential for robust plant growth. While needed in smaller quantities than the primary nutrients, they play critical roles in various physiological processes, such as chlorophyll production and nutrient absorption.

2. Trace Elements

Trace elements, or micronutrients, are essential in minute quantities for specific plant functions. Iron, manganese, zinc, copper, molybdenum, and boron are common trace elements found in fertilizers. These elements contribute to enzyme activation, photosynthesis, and overall metabolic processes.

As you become adept at decoding fertilizer labels, you'll be better equipped to choose the best blend for your lawn's unique requirements.

Customizing Fertilizer for Specific Needs

Soil Testing and Its Importance

Before starting a lawn fertilization schedule, it's crucial to assess the current state of your soil. Soil testing is a valuable tool that provides insights into the soil's nutrient composition, pH levels, and overall health. By understanding your soil's unique characteristics, you can tailor your fertilizer application to address specific deficiencies and optimize nutrient levels.

Steps for Soil Testing

  • Collect soil samples: Gather samples from different areas of your lawn, ensuring representation of the entire space.
  • Submit to the testing lab: Many agricultural extension services or private labs offer soil testing services. Send your soil samples for a comprehensive analysis.
  • Receive results: The soil test results will provide detailed information about nutrient levels, pH, and potential imbalances.
  • Interpret results: Understand the recommendations provided in the soil test report, focusing on nutrient deficiencies or excesses that may impact your lawn.


Adjusting Nutrient Levels Based on Soil Analysis

Armed with the soil test results, you can now make informed decisions about the type and quantity of fertilizer your lawn needs. Here's how you can adjust nutrient levels based on common scenarios:

1. Correcting Nitrogen (N) Deficiency

  • Choose a fertilizer with a higher first number (nitrogen content). 

Humic Max 16-0-8 — Lebanon Country Club Fertilizer is an excellent golf course quality granular fertilizer that will take your lawn to the next level.  

Humic Max contains 35% MESA slow-release nitrogen, which facilitates rapid greening without causing excessive growth. Additionally, 8% of the blend comprises 100% SOP (sulfate of potash) potassium, known for its non-burning nature and immediate availability to the grass. The added benefit of plant-available sulfur further enhances its effectiveness. 

When applied at the recommended rate of 3 lbs. per 1000 square feet and watered in, results become visible within five to seven days. At this rate, Humic Max adds 1/2 lb. of nitrogen per application and features 8.9% humic acid, optimizing soil health by helping the grass extract more from all soil nutrients. 

Humic Max 16-0-8 is a versatile fertilizer suitable for cool-season lawns (Kentucky Bluegrass, Turf Type Tall Fescue, Ryegrass) and warm-season lawns (Bermuda, St Augustine, Zoysia, Centipede, Bahia). With its unique blend and exceptional performance, Humic Max is undeniably one of the best fertilizers for achieving a deep green, healthy lawn.



2. Addressing Phosphorus (P) Deficiency

3. Boosting Potassium (K) Levels

  • Select a fertilizer with a higher third number (potassium content).
  • Look for potassium sources like potassium chloride or sulfate of potash (SOP). 

We highly recommend Stress 12-0-24 granular fertilizer as a natural mineral powerhouse, contributing to overall plant vigor, disease resistance, and stress recovery. With an analysis of 12-0-24, this fertilizer variant delivers potassium in a low-salt formula, ensuring optimal results for your lawn without the concerns of excessive salinity. 

The polymer coating introduces a controlled-release element to the product, offering a user-friendly lawn application. Unlike other sulfate of potash alternatives, this prilled SOP is designed for easy and efficient lawn use. 

    Stress 12-0-24 is suitable for both cool-season and warm-season lawns throughout the year, as long as the ground isn't frozen. Application to a dry lawn, followed by watering within 48 hours with 1/4" of irrigation or rainfall, ensures optimal absorption.


    Choosing the Right Fertilizer Formulation for Your Lawn

    Slow-Release vs. Quick-Release Fertilizers

    • Slow-release fertilizers: Release nutrients gradually over an extended period, providing a steady supply to the lawn. Ideal for reducing the risk of over-fertilization and promoting sustained growth.
    • Quick-release fertilizers: Release nutrients rapidly, offering a swift response to immediate nutrient needs. They are suitable for addressing specific deficiencies or providing a rapid green-up.

    Organic vs. Synthetic Fertilizers

    • Organic fertilizers: Derived from natural sources, organic fertilizers enhance soil structure and microbial activity. They release nutrients slowly and contribute to long-term soil health. 

    Mirimichi Green Organic Lawn Fertilizer and Biostimulant — 4-4-4 is our go-to organic fertilizer. It is a perfect solution for those seeking an organic lawn fertilizer enriched with biostimulants to enhance soil quality. This option is ideal for individuals looking to embrace a fully organic approach to their fertilization program.  

    Mirimichi Organic Fertilizer boasts several benefits, including easy spreading, slow-release nitrogen that avoids lawn burn, iron for a richer green lawn, humate for improved nutrient uptake, and the inclusion of beneficial fungi and bacteria for enhanced plant health. As an OMRI-listed organic product, Mirimichi Organic Fertilizer is a fantastic alternative to Milorganite, offering true organic composition, superior ingredients, and enhanced coverage value.



    Related: The Best Types of Organic Fertilizers for Your Lawn


    • Synthetic fertilizers: Manufactured with specific nutrient concentrations, synthetic fertilizers provide precise control over nutrient levels. They are often faster-acting but may require careful application to avoid overuse. 

    By customizing your fertilizer approach based on soil analysis and specific lawn needs, you ensure your lawn receives the best nutrients in the right proportions,  fostering optimal growth and contributing to long-term soil health and sustainability.

    Fertilization Timing and Frequency

    Seasonal Considerations for Fertilizing

    Understanding your lawn’s seasonal needs is pivotal in implementing an effective fertilization schedule. Different seasons bring distinct challenges and growth patterns, influencing the type and timing of fertilizer applications.



    Complete 14-7-14 - Lebanon Country Club Fertilizer combines fast-release nitrogen and Meth-Ex slow-release nitrogen, ensuring swift green-up without causing overgrowth. Notably, it includes 14% SOP (sulfate of potash) potassium, a non-burning and immediately available potassium source, with the added benefit of plant-available sulfur. 

    This lawn fertilizer incorporates a blend of iron, manganese, and magnesium to enhance the deep green appearance of your lawn, addressing both macro and micronutrient deficiencies. Sea kelp and humic acid complete the nutrient package to improve fertilizer uptake and overall plant health. 

    Application is straightforward, with a suggested rate of 3.5 lbs per 1000 sq. ft., resulting in visible results within five to seven days. As the primary growth stimulator in the golf course lawn program, Country Club should be applied every four to six weeks during the turf's growth mode. 

    Tailored for cool-season lawns and warm-season lawns from early spring through fall, this fertilizer ensures consistent feeding throughout the entire growing season. Give your lawn the best care with Lebanon Turf's Country Club Complete 14-7-14 Fertilizer, featuring a nutrient analysis of 14-7-14, 2% Iron, 1% Manganese, and 1.5% Magnesium.


    Related: The Best Lawn Fertilizers to Use This Spring



    • Objective: Address stress factors like heat and potential drought by promoting resilience.
    • Recommended fertilizer: To enhance stress tolerance, choose a formulation with a higher potassium content (third number), such as Stress 12-0-24 — Lebanon Country Club Fertilizer.

    Country Club Stress 12-0-24 fertilizer is a carefully crafted blend that promotes optimal lawn health and resilience. Combining fast-release nitrogen with Meth-Ex slow-release nitrogen, this formulation ensures a rapid green-up without inducing excessive growth. A significant portion of the granular blend comprises 24% SOP (sulfate of potash) potassium, known for its non-burning and immediately available nature, accompanied by plant-accessible sulfur. 

    To address micronutrient deficiencies and foster a deep green appearance, the fertilizer includes a strategic mix of iron, manganese, and magnesium. This combination, alongside the high potassium content, empowers your lawn to withstand the stresses of varying weather conditions throughout the seasons. The nutrient package is further enriched with sea kelp and humic acid, enhancing fertilizer uptake and overall plant health. 

    Application is straightforward, with suggested rates of 4 lbs per 1000 sq. ft. Watering in the fertilizer leads to visible results within five to seven days, and each bag covers an impressive 10,000 square feet while adding 1/2 lb of nitrogen. 

    Timing is crucial for optimal results. For cool-season lawns (Kentucky Bluegrass, Perennial Ryegrass, and Turf Type Tall Fescue), apply every four to six weeks during early spring, peak summer, and winter. Warm-season lawns (Bermuda, Zoysia, St Augustine, Centipede, and Bahia) benefit from this fertilizer during early spring through fall, supporting consistent feeding throughout the entire growing season. 

    With a nutrient analysis of 12-0-24, enriched with 1.6% iron, 0.5% manganese, and 0.5% magnesium, Lebanon Turf's Country Club Stress 12-0-24 is a top-tier choice to give your lawn the best care it deserves. 



    Why opt for BloomPlex? It offers faster establishment for new turf, corrects phosphorus deficiencies, suits all grass types, and provides a comprehensive micronutrient feeding package. With an analysis of 8-16-5, BloomPlex is compatible with various grass types, including cool and warm-season lawns. 

    Featuring benefits such as improved root establishment, enhanced stress tolerance, and a rich blend of essential nutrients, including nitrogen (N), phosphorus (P), potassium (K), iron (Fe), manganese (Mn), and zinc (Zn), BloomPlex addresses a range of concerns, from poorly established grass to phosphorus deficiency symptoms. 

    BloomPlex is best applied during the growth phases of your turf. Spring and fall are optimal times for cool-season lawns (Kentucky Bluegrass, Perennial Ryegrass, and Turf Type Tall Fescue). For warm-season lawns (Bermuda, Zoysia, St Augustine, Centipede, and Bahia), BloomPlex proves valuable from early spring through early fall, supporting consistent feeding throughout the growing season. 

    For ease of application, BloomPlex can be applied through foliar spray, either alone or tank-mixed with other products.


    • Objective: To prepare your lawn for dormancy, avoid high-nitrogen fertilizers that can stimulate new growth susceptible to cold damage.


    Use our lawn fertilization program calculator to work out what you need for your lawn.


    How Often Should You Fertilize Your Lawn?

    The frequency of fertilizer applications depends on several factors, including grass type, climate, and the specific needs of your lawn. For best results, we recommend monthly fertilizer applications using a spoon feeding program.

    For a more basic approach to lawn fertilization, here are some general guidelines:

    1. Regular Maintenance:

    • Apply a balanced fertilizer two to four times a year for general lawn upkeep.
    • Use slow-release formulations for consistent nutrient supply without the risk of over-fertilization. A great product to use is Lebanon Complete 14-7-14 granular fertilizer.

    2. Intensive Growth Periods:

    • During periods of active growth, such as spring and early summer, additional applications to support lush greenery should be considered.

    3. Avoiding Excessive Fertilization:

    • Over-fertilization can harm your lawn, leading to nutrient imbalances, excessive growth, and environmental pollution.
    • Follow recommended application rates and adjust based on soil test results. 

    Check out the guidelines and tips from the Environmental Protection Agency (EPA) on responsible lawn fertilization to prevent nutrient pollution.

    Tips for Avoiding Over-fertilization

    1. Measure Accurately:

    Use calibrated spreaders to ensure even distribution and prevent overapplication.

    2. Follow Labeled Instructions:

    Adhere to the recommended application rates provided on the fertilizer label.

    3. Water Appropriately:

    Water your lawn after fertilizing to help nutrients penetrate the soil and reduce the risk of fertilizer burn.

    4. Be Mindful of Environmental Factors:

    Consider weather conditions before fertilizing; heavy rain may lead to runoff, while drought conditions may necessitate additional watering. 

    By aligning your fertilization schedule with the changing seasons and adhering to proper frequency guidelines, you can provide your lawn with the nutrients it needs when it needs them most.


    Related: Top Tips for Fertilizing Your Lawn: Choosing the Right Lawn Fertilizer


    Troubleshooting Common Issues

    Identifying Nutrient Deficiencies Based on Symptoms

    Healthy lawns can face challenges, and recognizing the symptoms of nutrient deficiencies is crucial for effective troubleshooting. Here's a guide to common signs and their corresponding nutrient needs:

    1. Yellowing of Leaves (Chlorosis)

    Nitrogen deficiency: Address with a nitrogen-rich fertilizer such as 24-0-6 Flagship 3% Iron — Bio-Nite — Granular Lawn Fertilizer.



    2. Stunted Growth and Poor Root Development

    Phosphorus deficiency: Choose a fertilizer with a higher phosphorus content, like BloomPlex Liquid Fertilizer (8-16-5) with Micronutrients.

    3. Brown or Scorched Edges

    Potassium deficiency: Opt for a fertilizer with a higher potassium content, such as Stress 12-0-24 Granular Lawn Fertilizer.

    Adjusting Fertilizer Applications to Address Issues

    1. Spot Treatments

    For localized nutrient deficiencies, consider spot treatments with a targeted fertilizer or amendments.

    2. Repeat Soil Testing

    Periodic soil testing helps monitor nutrient levels and allows for adjustments based on changing soil conditions.

    3. Consider Specialized Formulations

    Explore fertilizers designed to address specific issues, such as iron supplements for correcting iron deficiencies.


    Related: What Is a Lawn Biostimulant & Why Are They Important?


    Complementing Fertilization with Weed Control

    Achieving a lush, healthy lawn involves more than just fertilization. Weeds can pose a significant threat to the well-being of your grass, competing for nutrients, water, and sunlight. Integrating weed control measures with your fertilization routine ensures a comprehensive approach to lawn care.

    1. Nutrient Competition

    Weeds often thrive in nutrient-rich environments, taking advantage of the imbalances in your lawn. Fertilizing strategically helps maintain a competitive edge for your grass.

    2. Promoting a Robust Lawn

    A well-fed lawn is better equipped to resist weed invasions. Fertilizing supports dense, vigorous grass growth, reducing the opportunities for weeds to establish themselves.

    Choosing Fertilizers with Weed Control Features



    To streamline your lawn care efforts, some fertilizers include pre-emergent herbicides, preventing weed seeds from germinating and establishing in your lawn. For instance, Prodiamine .38% Pre-Emergent Herbicide with Fertilizer 0-0-7 or Dimension .15% Pre-emergent Herbicide with Fertilizer 0-0-7 

    Related: When Should You Apply Weed and Feed? 


    Achieving a lush and vibrant lawn involves making informed choices about the fertilizers you use. Whether you're aiming for golf course-quality grass, addressing specific deficiencies, or embracing an entirely organic approach, there's a fertilizer solution to meet your unique lawn care needs. By tailoring your fertilization routine, integrating weed control measures, and adopting eco-friendly practices, you can nurture a resilient and beautiful lawn that stands the test of time. 

    If you want to raise your lawn care game, we invite you to explore our range of high-quality fertilizers, weed killers, and lawn care products