Bright sunlight shining on green grass in summer time

The Best Lawn Fertilizers for Summer

Fertilizing lawns in the summer requires careful planning to avoid stressing the grass during hot and dry conditions. The best fertilizers for summer use typically provide a balanced supply of nutrients in a slow-release form, supporting steady growth without promoting excessive leaf development or burning the grass. All fertilization applications should be based on soil test results, and here are some top options and considerations for fertilizing lawns in the summer. 

Nitrogen Fertilizers

Generally during the peak of summer, slow-release nitrogen fertilizers or a fertilizer with lower values of nitrogen are recommended for cool-season lawns. Slow-release nitrogen provides a gradual supply of nitrogen, the primary nutrient that supports grass growth, minimizing the risk of burning and encouraging consistent growth.

These fertilizers are especially beneficial for lawns, as they minimize the need for frequent applications and help maintain healthy turfgrass throughout the growing season. Fertilizers with a lower Nitrogen analysis, paired with micronutrients such as iron, manganese, and zinc are essential for maintaining lawn vigor and color, particularly during summer stress.



Lawn Energizer liquid iron and nitrogen fertilizer applied with a hose-end sprayer to the lawn


For warm-season lawns, especially lawns located in the southern states, the summer is the peak growing phase, so a higher nitrogen product can be applied as long as there are no drought-like conditions present.


Phosphorus and Potassium Fertilizers

Knowing that many areas of the US can be prone to heat waves in summer, it is important to ensure that your lawn has access to an adequate nutrient profile before the heat sets in. Potassium and phosphorus are critical nutrients for turfgrass health, especially before the hot summer months. Here’s why they are important:

Potassium enhances the plant's ability to manage water efficiently by regulating stomatal opening and closing, reducing water loss which is essential during times of heat stress​​.

Phosphorus is crucial for root development, as strong and extensive root systems help the turf absorb more water and nutrients, supporting the plant during the stress of high temperatures.


Simple Lawn Solutions 3-18-18 NPK and 0-0-25 High Potassium Lawn Fertilizers


Fertilizers with Humic Acid 


A healthy lawn begins in the soil, and humic acid provides several benefits for lawns during the summer, including supporting moisture retention and enhanced nutrient uptake. The primary advantages come from optimizing soil conditions for plant vigor, which can support your lawn during the hot summer heat.

Simple Grow Solutions Root Hume, Sea Hume, and Seaweed Soil Hume on a green lawn



Liquid Lawn Fertilizers


Liquid fertilizers are a popular option for turfgrass care due to their quick nutrient delivery and ease of application. They come in various formulations and can be applied through different methods, offering flexibility in meeting the specific needs of your lawn. 


Ideal for quickly addressing nutrient deficiencies or stress conditions in turfgrass, liquid fertilizers, when correctly applied, ensure an even distribution of nutrients across the lawn, avoiding hot spots or uneven growth. They can be mixed with water and applied uniformly using sprayers, making it easier to cover large areas efficiently.  Liquid fertilizers allow for precise control over nutrient application rates and can be tailored to the specific needs of the lawn.  


Liquid fertilizers are suitable for both cool-season and warm-season grasses and can be used throughout different stages of turfgrass growth. Four different types of liquid fertilizers exist with the same formulations as granular fertilizers, but granular and liquid formulations differ in their application methods. Granular fertilizers must be used with a rotary-type spreader, while liquid fertilizers can be applied via a hose-end sprayer, tank sprayer, or irrigation system.


Liquid fertilizers offer a versatile and efficient way to maintain and improve turfgrass health. They provide rapid nutrient delivery, uniform application, and the flexibility to address specific lawn care needs. By selecting the correct type of liquid fertilizer and applying it according to best practices, you can achieve a lush, green, and healthy lawn. 

Timing and Frequency of Application


Apply fertilizers during cooler parts of the day to minimize the risk of burning the grass and to allow better absorption.  Do not fertilize during the hottest parts of the day or prolonged heat waves, as this can stress the grass further. A light application every 6-8 weeks may be beneficial for warm-season grasses. For cool-season grasses, consider minimal or no fertilization during peak summer heat, reserving more substantial applications for early fall. 


If the soil is dry, lightly water the lawn before applying fertilizer. This helps prevent fertilizer burn and ensures better nutrient uptake. Water the lawn thoroughly after fertilization to help dissolve the fertilizer and carry nutrients into the root zone. Maintain consistent moisture levels during the summer to support nutrient absorption and mitigate heat stress. 


Man Applying Liquid Fertilizer with hose-end sprayer and tips for application


Practical Steps for Summer Fertilization


Reduce or avoid fertilization if the lawn is under severe drought stress. Fertilizer salts can further dehydrate the grass and cause damage. Use starter fertilizers with lower nitrogen and higher phosphorus to support root development without overstimulating top growth on newly seeded lawns and sod. Consider the presence of weeds. Fertilization can inadvertently benefit weeds, so integrating weed control measures may be necessary. 


Apply fertilizer early in the summer, ideally in late spring or early summer, when grass growth is active and temperatures are moderate. Avoid fertilizing during extreme heat or drought periods to prevent stress on the grass. Cut the grass to an appropriate height before applying fertilizer. This ensures better nutrient uptake and even distribution of the fertilizer.  Choose a day when rain is not expected shortly after application to prevent runoff and ensure the soil absorbs nutrients.  Calibrate your spreader or sprayer according to the manufacturer's instructions to apply the correct amount of fertilizer evenly across the lawn. Apply fertilizer evenly to prevent streaks or patches of over-fertilization, which can damage the grass.  Lightly water the lawn after applying fertilizer to help activate the nutrients and move them into the soil, where the roots can absorb them. 


About Summer Fertilization


Fertilizing during the summer requires a careful selection of products and thoughtful application to support your lawn's health without causing stress or environmental issues. By considering the specific needs of your grass type, choosing appropriate fertilizers, and following best practices, you can maintain a vibrant, resilient lawn throughout the summer. Always read and follow product labels for safe and effective use.

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