How Ammonium Sulfate Can Help Green Up Summer Grass

Summer brings intense heat, frequent mowing, and periods of drought stress that can turn your once-lush green lawn into a patchy, yellowing mess. While many homeowners reach for general-purpose fertilizers to revive their grass, few products are as uniquely effective at restoring color and vigor as ammonium sulfate (21-0-0-24S).

In this comprehensive guide, we’ll explore how ammonium sulfate works, why it’s ideal for mid-season lawn recovery, how it compares to other nitrogen sources, and how to use it correctly to prevent burning while maximizing your results.

Why Lawns Turn Yellow in Summer

Before diving into ammonium sulfate’s benefits, it’s important to understand why grass loses its vibrant green color in the summer months:

• Nitrogen deficiency: Grass uses up spring fertilizer by mid-summer, especially in fast-growing species.
• Drought and heat stress: High temperatures reduce photosynthesis and slow root activity.
• Frequent mowing: Removes the top growth where much of the nitrogen is stored and used.
• Nutrient leaching: Heavy rains or irrigation can wash nitrogen and sulfur below the root zone.

These factors combined create the perfect conditions for lawn discoloration, poor density, and vulnerability to pests or disease.

What is Ammonium Sulfate?

Ammonium sulfate ((NH4)2SO4) is a synthetic fertilizer that delivers two critical nutrients:

• 21% nitrogen (ammonium form): Supports rapid greening and blade development
• 24% sulfur: Enhances chlorophyll formation, enzyme function, and protein synthesis

This unique 2-in-1 formula is especially beneficial for lawns experiencing mid-season nutrient depletion and soil imbalances.

Advantages of Ammonium Sulfate for Summer Lawns

1. Quick Greening Response

The ammonium form of nitrogen provides an immediate boost to turfgrass, fueling chlorophyll production and visible green-up within days.

2. Acidifies Alkaline Soils

Ammonium sulfate slightly lowers soil pH, helping improve nutrient uptake in high-pH soils (common in arid or heavily irrigated regions).

3. Ideal for Cool-Season Grasses in Summer

Cool-season grasses like Kentucky bluegrass and fescues often suffer in summer. A quick, controlled nitrogen dose from ammonium sulfate helps them bounce back without overstimulating top growth.

4. Combats Sulfur Deficiencies

Sulfur is often overlooked in lawn care, but it’s essential for root vigor and greening. Symptoms of sulfur deficiency resemble nitrogen deficiency but are more common in sandy or leached soils.

5. Less Volatile Than Urea

Ammonium sulfate has a lower risk of nitrogen loss via volatilization, making it a more efficient option in hot summer weather compared to urea-based fertilizers.

How to Apply Ammonium Sulfate on Lawns

Application Rate

• Apply 5 to 10 lbs per 1,000 sq. ft. depending on your lawn’s nitrogen needs.
• Use the lower end for light feeding or new lawns; the higher end for established lawns showing yellowing.

Timing

• Apply during the coolest part of the day, ideally early morning or late evening.
• Water the lawn immediately after application to dissolve the granules and activate the nutrients.
• Reapply every 4–6 weeks throughout the summer, especially after periods of heavy rainfall.

Spreader Settings

Check your spreader’s manual for ammonium sulfate settings, as it has a finer texture than standard fertilizers. Consider using a drop spreader for precision near sidewalks or flower beds.

Common Mistakes to Avoid

• Over-application: Can lead to salt build-up or burn, especially if not watered in properly.
• Applying to dry soil: Increases risk of leaf scorch.
• Not watering after spreading: Always water deeply to ensure safe and effective nutrient delivery.

Compatibility With Other Lawn Products

Ammonium sulfate can be safely combined with:

• Pre-emergents (e.g., dithiopyr or prodiamine)
• Post-emergent herbicides (after a week or two buffer)
• Micronutrient supplements for iron or magnesium
• Compost teas or organic topdressings to improve microbial activity

Avoid using it alongside:

• Other high-nitrogen products (to reduce overfeeding)
• Lime applications (as it may negate the acidifying benefits)

Environmental Considerations

Although ammonium sulfate is synthetic, it is relatively safe for the environment when used correctly:

• Store in a dry place to prevent clumping and nutrient loss.
• Avoid runoff: Don’t apply before heavy rains.
• Sweep granules off hard surfaces to avoid contaminating stormwater systems.

Real Results From Homeowners and Professionals

“I had a patchy backyard that looked dead by July. One application of ammonium sulfate greened it up in 5 days—now it’s the best part of the yard.”

“As a turf professional, I’ve stopped using urea mid-summer. Ammonium sulfate gets the job done fast and doesn’t burn when used properly.”

Final Thoughts

If your lawn is fading under the summer sun, ammonium sulfate offers an efficient, fast-acting solution that restores color, density, and plant health. Its dual-action nitrogen and sulfur formula makes it particularly valuable in tough growing conditions where standard fertilizers fall short.

Looking for high-quality ammonium sulfate? Supply Solutions LLC offers trusted, professional-grade options that deliver results.

Have questions or need a custom lawn plan?

• Call us at 503-451-1622
• Email sales@mysolutionssupply.com
• Use our Contact Form
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Let Supply Solutions LLC help you bring your summer lawn back to life.