The Best Summer Lawn Fertilizers to Keep Your Grass Green and Healthy

Summer is when your lawn takes center stage. With the sun shining and outdoor gatherings in full swing, it’s the perfect time to show off a lush, green lawn. But summer can be tough on grass, with scorching heat, inconsistent rainfall, and high foot traffic. That’s where the right summer lawn fertilizer comes into play. 

In this guide, we’ll dive into the best options for summer lawn care, from understanding the best summer lawn fertilizer numbers to knowing how to keep your grass green even in the most challenging conditions to achieve that envy-worthy lawn.

Why Is Summer Lawn Fertilizer Important?

Summer brings higher temperatures and, in many areas, less rainfall. This combination can stress your grass, making it more vulnerable to pests, diseases, and browning. A quality summer fertilizer provides the essential nutrients your lawn needs to:

  • Stay green and vigorous: Nitrogen promotes rich, green growth.

  • Resist stress: Potassium enhances drought tolerance and disease resistance.

  • Develop strong roots: Phosphorus supports root growth for overall health.

By using the right fertilizer at the right time, you’re not just maintaining your lawn; you’re setting it up for long-term success.

What to Look for in a Summer Lawn Fertilizer

When selecting a fertilizer for summer, consider these key factors:

  1. Slow-release nitrogen: A steady supply of nitrogen prevents quick growth spurts, which can stress your grass.

  2. Nutrient ratios: Check the NPK numbers (nitrogen-phosphorus-potassium). For summer, look for formulas like 16-0-8, 20-2-3, or 14-4-10, which provide sufficient nitrogen and potassium without excess phosphorus.

  3. Organic options: Organic fertilizers are great for improving soil health while being eco-friendly.

  4. Micronutrients: Iron, magnesium, and other micronutrients help enhance your lawn’s color and overall health.

The 5 Best Summer Lawn Fertilizers

Three bags of Lebanon Turf Country Club MD blended fertilizers

1. Lebanon Country Club Humic Max 16-0-8 — The Best Summer-long Fertilizer for Warm-Season Turf

This professional-grade fertilizer combines slow-release nitrogen with humic acid to improve soil health and nutrient uptake. The 16-0-8 formula is ideal for warm-season grass in summer because:

  • Humic Max contains 35% MESA slow-release nitrogen that produces fast green-up without causing overgrowth.

  • 8.9% of the Humic Max blend is 100% SOP (sulfate of potash) potassium that is non-burning and immediately available to the grass. Humic acid helps your grass get more out of all soil nutrients.

  • It contains no phosphorus, which is often unnecessary for established lawns.

Apply every 4-6 weeks during the summer for consistent results.


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2. Lebanon Country Club Stress 12-0-24 — The Best Fertilizer for Cool-Season Lawns That Don’t Like the Summer Heat

Designed specifically for summer, this granular fertilizer’s high potassium content strengthens grass against heat and drought. The low nitrogen reduces excessive growth, making it perfect for mid-to-late summer applications. Stress 12-0-24 will get your grass through the toughest conditions during cold snaps and hot summers:

  • Stress 12-0-24 contains a mix of fast-release nitrogen and Meth-Ex slow-release nitrogen, ensuring quick green-up without promoting excessive growth.

  • 24% of the Country Club granular fertilizer blend is 100% SOP (sulfate of potash) potassium, non-burning, and immediately available to grass.

  • This potassium also provides plant-available sulfur, enhancing nutrient uptake.

  • It combines iron, manganese, and magnesium to address micronutrient deficiencies, promoting a deep green lawn.

  • The high potassium content and micronutrient blend help your golf course lawn withstand the stresses of early spring, summer, and winter weather.

  • Sea kelp and humic acid are included to improve nutrient absorption and overall plant health.

Apply at 4 - 5 lbs per 1,000 square feet every 4-6 weeks.


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3. Greens Plus 14-4-10 — The Best Slow-Release Liquid Fertilizer

This liquid fertilizer is a fantastic choice for quick results. Its high nitrogen content promotes vibrant green growth, while the small amount of phosphorus supports overall plant health. It can be used on warm and cool-season grasses. It’s ideal for:

  • Consistent growth and color without burning your lawn

  • Enhancing stress tolerance

  • Low-vigor turf prone to mid-summer stress

  • Supplementing granular fertilizers.

Use a battery-powered 4-gallon sprayer with a TeeJet foliar spray tip to apply evenly.


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We highly recommend using Golf Course Lawn Micronutrient Blend — Liquid Fertilizer (with 2% Iron) alongside Greens plus 14-4-10 to get that gorgeous deep green turf.  Golf Course Lawn Micronutrient Blend is our custom blend of Boron, Copper, chelated Iron, Molybdenum, Manganese, and Zinc. These nutrients are all available via foliar uptake, meaning they are absorbed by the plant directly through the leaves. This blend of micronutrients is formulated in the same ratio as they occur naturally in the plant. It is chelated with a combination of citric and other organic acids, which stabilize nutrients and enhance their uptake.


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4. CarbonizPN-G™ — The Best Organic Fertilizer Enhancer

The newest product from Mirimichi Green, CarbonizPN-G™ is designed to improve soil microbial activity, water retention, and nutrient uptake. It is a unique blend of soil-amending ingredients combined with CarboMatrix™.

CarboMatrix™ is activated carbon (biochar) inoculated with premium organics. It reduces soil compaction, drives root growth, increases fertility, and improves water absorption. Biochar also decreases nutrient leaching, which helps fertilizer applications feed your grass longer.

CarbonizPN-G™ contains premium organics, biochar, and compost. It contains natural, reclaimed waste stream inputs to improve the soil. It increases soil organic material, allowing the soil to hold nutrients and moisture. It can be applied anytime throughout the year as long as the ground isn't frozen.

We recommend applying CarbonizPN-G™ using a traditional broadcast spreader like the Earthway 2050P before your granular or liquid fertilizer. It does not need to be watered in immediately after application; wait for it to rain or water in when you apply your fertilizer.

CarbonizPN-G™ is the replacement for Essential-G™. It contains a higher percentage of biochar and has been engineered for improved soil penetration.


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5. Release 901C™ — The Best Biostimulant with Fertilizer

Release 901C™ is designed to improve soil quality during active growing months. It is a liquid fertilizer and biostimulant that improves nutrient availability and accelerates uptake. This combo sports 9% nitrogen and 1% potassium for a vibrant lawn. It provides all the benefits of Release Zero™ and can supply essential nutrients through the leaves and root system. There is no need to water it in. Simply spray and go on with your day!

  • 9% nitrogen and 1% potassium for visible results in 2-3 days

  • 10% liquid carbon and micronutrients to boost soil biology

  • Formulated to protect turf from heat and drought

  • Safe for all grass types.


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Tips for Fertilizing Lawn in Summer

A lawn care technician using a red spreader
  1. Time it right: Fertilize early in the morning or late in the afternoon to avoid the midday heat.

  2. Water properly: Water your lawn deeply after fertilizing to ensure the nutrients are absorbed and to prevent burning.

  3. Mow smart: Keep your mower blades sharp and avoid cutting more than one-third of the grass's height. Taller grass provides shade for the soil, reducing water evaporation.

  4. Aerate if needed: Compacted soil can hinder nutrient absorption. Aeration helps nutrients reach the roots more effectively.

  5. Use the right tools: Whether you’re spreading granular fertilizer or spraying liquid options, using high-quality tools ensures even application.


Related: Liquid vs Granular Fertilizer: Which Is Best for Your Lawn Needs 


Common Summer Lawn Challenges and How to Address Them

A spacious garden lawn with neatly trimmed grass

1. Lawn Turning Brown

Dry, brown patches could be due to heat stress or drought. Use a moisture manager like FOURPlay™. This incredible product:

  • Eliminates localized dry spots

  • Reduces drought stress and wilt

  • Reduces watering requirements

  • Maximizes water efficiency

  • Improves water penetration

  • Increases seed germination and sod establishment

  • Improves plant establishment

  • Increases nutrient uptake

  • Improves stress tolerance

  • Provides a source of carbon

  • Provides microbial food source.


fourplay-lawn-dry-spot-moisture-manager


2. Pests and Diseases

Summer heat can invite unwanted guests. Pair your fertilizer with insecticides and fungicides to tackle these issues.

3. Uneven Growth

If some areas of your lawn aren’t thriving, a soil test might reveal nutrient deficiencies. A soil test kit can help you identify and address specific needs.


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Related: How to Keep Your Lawn Green in the Summer Heat 


Summer Fertilizer FAQs

How do you keep your grass green in the summer?

The key is consistent care:

  • Water deeply and less frequently.

  • Fertilize with a slow-release formula.

  • Mow higher to reduce stress.

  • Address pests and diseases promptly.

What are the best summer lawn fertilizer numbers?

Look for formulas with potassium and moderate nitrogen, such as 16-0-8, 15-0-15, or 12-0-24. These support growth and stress tolerance without overloading your lawn.

Is organic fertilizer effective in summer?

Absolutely! Organic options like CarbonizPN-G™ improve soil health over time, making your lawn more resilient to summer challenges. Pair it with this organic lawn fertilizer for great results.

Can you fertilize during a heatwave?

It’s best to avoid fertilizing during extreme heat. If you must, use a slow-release formula and water deeply immediately after application to prevent lawn burn.

How often should you fertilize in summer?

Most summer fertilizers can be applied every 4-6 weeks. Always follow the product’s instructions to avoid over-fertilizing, which can stress your lawn.

What’s the best way to apply summer fertilizer?

Use a broadcast spreader like the Earthway 2050P for granular fertilizers and a battery-powered 4-gallon sprayer with a TeeJet foliar spray tip for liquids. Ensure even coverage to prevent patchy growth.


Related: Your Summer Lawn Care Schedule 


Choose the Best for Your Lawn

Keeping your lawn green and healthy in the summer doesn’t have to be a struggle. With the right summer lawn fertilizer, proper watering, and smart maintenance practices, your grass can thrive even in the hottest months. For top-quality products and expert advice, GolfCourseLawn.store has everything you need to make your lawn the envy of the neighborhood.

Ready to get started? Browse our range of summer lawn fertilizers today and give your grass the care it deserves!

Ron Henry

Ron Henry is the founder of Golf Course Lawn, which is dedicated to helping homeowners achieve golf course-quality lawns. With expert knowledge in turf care, fertilization, and weed control, he shares practical tips and product recommendations to create lush, healthy lawns.