When To Fertilize Lawn In Summer

Knowing when to fertilize lawn in summer is one of the most important decisions you’ll make for your grass this season. Getting it wrong can lead to burnt grass or weak growth, but getting it right sets you up for a resilient, green yard.

Summer lawn care is about balance. The heat, sun, and often drought conditions put stress on your grass. Your goal is to support it without pushing for excessive growth that can’t be sustained. This guide gives you clear, practical steps to feed your lawn correctly during the hottest months.

This is the core question, and the answer depends heavily on your grass type and your local climate. There is no universal date.

For cool-season grasses like Kentucky bluegrass, fescue, and ryegrass, the general rule is to avoid heavy fertilizing in peak summer. These grasses prefer cooler temperatures and naturally slow their growth when it’s hot. The best time to feed them is late spring or early fall. If you must fertilize in summer, do it very lightly and only if the lawn is showing signs of nutrient deficiency and is not under drought stress.

For warm-season grasses like Bermuda, Zoysia, St. Augustine, and Centipede, summer is their prime growing time. These grasses thrive in the heat. The ideal schedule is to fertilize after they’ve fully greened up in late spring and then again in mid-summer, around 6-8 weeks later. A third application in late summer might be appropiate for some varieties.

Key Factors for Your Summer Fertilizing Decision

Grass Type: This is the biggest factor, as outlined above.
Local Climate: Are you in a humid southern state or a dry western region? Adjust timing for your typical heat patterns.
Current Lawn Health: Is your lawn already stressed from heat or lack of water? Never fertilize a stressed lawn.
Fertilizer Type: Using a slow-release formula is non-negotiable for summer applications.

The Golden Rule: Never Fertilize During Drought or Extreme Heat

This cannot be overstated. Applying fertilizer when the lawn is dormant, brown, or severely heat-stressed forces it to try to grow. Without adequate water to support that growth and process the nutrients, the grass will burn and roots can be damaged. If you’re under water restrictions or a heatwave, postpone your feeding plans.

How to Check if Your Lawn is Too Stressed for Fertilizer

Perform the “footprint test.” Walk across the lawn. If your footprints remain visible for several minutes, the grass blades lack moisture and are stressed.
Look for widespread bluish-gray tints or wilting.
Check soil moisture by inserting a screwdriver 6 inches down. If it’s dry and hard to push in, the soil is too dry.

Choosing the Right Summer Fertilizer

Not all lawn food is created equal, especially for summer. You need to read the bag carefully.

Slow-Release Nitrogen (N): This is essential. Look for terms like “polymer-coated,” “sulfur-coated,” or “methylene urea” on the label. It feeds the grass gradually over 6-8 weeks, preventing a surge of growth that’s vulnerable to heat.
Lower Nitrogen Content: A summer fertilizer blend often has a lower first number (N) than a spring feed. Something like a 15-0-5 or 20-0-10 is common.
Potassium (K): The third number (Potash) is crucial for summer. Potassium strengthens grass plants, improves drought tolerance, and helps with disease resistance. Ensure this number is decently high.
Weed & Feed Caution: Avoid summer applications of weed-and-feed products. The herbicides in them can damage grass when it’s under heat stress, and they’re often not the right weed control for mid-summer anyway.

The Step-by-Step Summer Fertilizing Process

Mow Beforehand: Mow your lawn a day or two before you plan to fertilize. Bag the clippings if they are long to ensure the granules reach the soil.
Water Deeply: About 24 hours before applying fertilizer, give your lawn a good, deep watering. This helps prepare the soil and ensures the grass isn’t thirsty.
Calibrate Your Spreader: Use the setting recommended on the fertilizer bag for your spreader type. This ensures you apply the correct amount. Too much is dangerous.
Apply in a Pattern: Fill your spreader on a hard surface. Apply fertilizer in two perpendicular passes (e.g., north-south, then east-west) to avoid striping and ensure even coverage. Keep it off driveways and sidewalks.
Water Lightly After: Lightly water the lawn immediately after application. This washes the granules off the grass blades and into the soil, preventing burn and starting the feeding process. This is called “watering in.”

Essential Summer Lawn Care Beyond Fertilizing

Fertilizing is just one piece of the puzzle. To keep your lawn healthy in summer, you must combine it with these practices:

Smart Watering

Deep, infrequent watering is the goal. It encourages roots to grow deeper in search of moisture. Water early in the morning to reduce evaporation.

Aim for 1 to 1.5 inches of water per week, including rainfall.
Use a tuna can on your lawn to measure how much water your sprinklers deliver.
It’s better to water twice a week deeply than to water a little every day.

Proper Mowing Height

Raise your mower blade in summer. Taller grass shades the soil, keeping it cooler and reducing water evaporation. It also helps crowd out weeds.

Cool-season grasses: Mow at 3-4 inches.
Warm-season grasses: Mow at the higher end of their recommended range (e.g., Bermuda at 1.5-2 inches, Zoysia at 2-2.5 inches).
Never remove more than 1/3 of the grass blade in a single mowing.

Managing Weeds and Pests

Summer brings specific challenges. Spot-treat weeds rather than blanket spraying. Watch for signs of grub damage or fungal diseases like brown patch, which thrive in hot, humid conditions. Often, improving your watering and mowing practices can prevent many of these issues.

Troubleshooting Common Summer Lawn Problems

Yellowing Grass: Could be overwatering, underwatering, or a nutrient deficiency. Check your soil moisture first before assuming it needs food.
Brown Patches: Check for disease, grubs, or localized dry spots. A simple tug test can help—if the grass pulls up easily like loose carpet, you might have grubs.
Slow Growth: This is normal for cool-season grasses in heat. For warm-season grasses, it might indicate a need for fertilizer or more water.
Fertilizer Burn: Appears as yellow or brown streaks or patches shortly after application. Usually caused by over-application, applying to wet grass, or not watering in properly. Water heavily to dilute the salts and hope for recovery.

FAQ: Summer Lawn Fertilizing Questions

Can I fertilize my lawn in July?

For warm-season grasses, yes, mid-summer (like July) is often a good time for a second application. For cool-season grasses, it’s generally not recommended unless conditions are mild and the lawn is healthy and well-watered.

Is it too late to fertilize in August?

For warm-season grasses, a late-summer feeding can be beneficial to prepare for fall. For cool-season grasses, it’s better to wait until early fall (September) for your next major feeding, which is the most important of the year.

What temperature is too hot to fertilize lawn?

Avoid fertilizing when daytime temperatures are consistently above 85°F for cool-season grasses. For warm-season grasses, watch for forecasted heatwaves above 95°F; it’s best to apply just before a milder period.

Should I water after fertilizing in summer?

Absolutely. Watering lightly immediately after applying fertilizer is a critical step to move the granules into the soil and prevent them from burning the grass blades.

Can I use the same fertilizer I used in spring?

You can, but check the formulation. A spring fertilizer might have a very high nitrogen content that’s too aggressive for summer. Opt for a summer-specific or slow-release blend for safer, more effective results during the heat.

Successfully navigating summer lawn care comes down to understanding your grass and working with the weather, not against it. By timing your fertilization correctly, choosing the right product, and combining it with proper mowing and watering, you give your lawn the best chance to stay healthy and green through the challenging summer months. Remember, the goal is maintainance and strength, not forcing lush growth. With a little observation and these steps, your lawn can look it’s best all season long.