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Summer Care Tips for Your St. Augustine Lawn

In the summer heat, proper care for St. Augustine grass is vital to maintain a vibrant, healthy lawn. Essential practices include mowing at the ideal height for St. Augustine, watering efficiently to prevent excessive moisture and choosing fertilizers that bolster St. Augustine during stressful conditions. Equally important are effective weed and pest control strategies and disease prevention tailored to St. Augustine’s specific needs. This guide delivers expert advice for nurturing St. Augustine grass, ensuring it flourishes throughout the summer months.

Be sure to also check out our series of Homeowner Maintenance Guides for generic St. AugustinePalmetto® St. Augustine and CitraBlue® St. Augustine.

Want us to do some of the summer lawn care for you?

If so, check out the Lawnifi Complete Program! The Lawnifi Complete Program is a year-round subscription for seasonal lawn care delivered to your door. Our boxes include everything your lawn needs in one lawn care subscription. Products are curated by our turfgrass experts for each active growing season. Delivered spring, summer and fall.

1. Keep Up with Summer Mowing (and Reduce the Time Spent on This Chore)

Summer mowing can be challenging due to the heat and the need for frequent cuts to manage grass growth. For St. Augustine grass, ideal mowing heights are 2–4 inches, with shaded areas needing 3–4 inches. Recommended heights for specific varieties are:

  • Palmetto: 2–2.5 inches
  • CitraBlue: 2–3 inches
  • Floratam: 3–4 inches

Always trim no more than a third of the grass blade to prevent stress and browning. If you go on a vacation or break and your grass gets too tall while you’re gone, mow gradually to the desired height, allowing 3–5 days between mowings. Taller blades benefit the lawn by shading the root system and retaining moisture.

Note: Get ahead of summer mowing and check out our tips on reducing time spent mowing your lawn as it gets hotter outside: How to Mow Your Lawn Less During the Summer.
Side Angle Of Man Pushing Lawn Mower Grass In Summer

2. Keep Your Heat-Stressed St. Augustine Strong with the Right Summer Fertilizer

St. Augustine grass needs tailored nutrients as seasons change, especially to combat summer heat stress. It requires less nitrogen in summer to avoid scorching under intense heat and sunlight.

Sod University suggests two summer fertilizer options, but recommends using only one:

  1. Lawnifi® Summer Fertilizer Box: A liquid fertilizer set designed for St. Augustine lawns, including one bottle of Maintain (16-0-4) for potassium, amino acids, and carbon, and two bottles of Recover (13-0-0) for an optimal nutrient balance plus essential micronutrients. It attaches easily to a garden hose for application.
  2. Lawnifi Foundation: A 25-pound bag of granular fertilizer with a 29-0-5 NPK ratio, providing slow-release nitrogen and 2 percent iron for a prolonged, healthy lawn growth without nitrogen overload.

Both products cover 5,000 sq. ft.

Summer Fertilizer Box

Lawnifi is a liquid fertilizer program powered by Catalyst Technology. For optimal results, feed your lawn monthly during the active growing season (spring, summer, fall). Simply attach a hose to the sprayer top and apply evenly to your lawn.

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3. Make Sure Your St. Augustine is Hydrated…But Not Too Hydrated

Despite the temptation to water more in summer, St. Augustine grasses typically need only 1 inch of water weekly, including rainfall, to avoid disease-promoting waterlogged conditions. Aim for one or two deep waterings early in the morning each week to minimize dew duration and reduce disease risk and take rainfall into consideration.

watering lawn with ground irrigation landscape

Watering in the early morning decreases the amount of time dew is present, which is helpful for managing any potential disease outbreaks. Unsure of measuring water? Try an irrigation audit. If heat stress appears, top dressing may help cool and protect your lawn.

4. Be Cautious with Weed Control

dollar weed close up in grass

Applying weed control to St. Augustine grass in summer can harm it, especially when temperatures exceed 85°F. It’s safer to apply post-emergent herbicides when it’s cooler and use pre-emergent herbicides in spring and fall to manage seasonal weeds.

If below 85°F, you can cautiously apply post-emergent herbicides, but it’s advised to wait for cooler fall conditions to avoid risk, as subsequent hot days can still cause damage.

For more details, see How to Control Weeds During the Summer. Common summer weeds include dollarweed, knotweed, spurge, lespedeza, crabgrass, goosegrass, nutsedge and sandspur.

Pictured above: Dollarweed.

 Be sure to read herbicide labels thoroughly before application.

Hi-Yield Atrazine Weed Killer

Hi-Yield Atrazine Weed Killer is an atrazine-based herbicide designed to control weeds like henbit, dollar weed, chickweed, clover, sandspur and others listed on the product label in St. Augustine and centipede grass. Available in a single quart bottle or single quart ready-to-spray bottle.

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5. Watch Out for Insect Infestations or Damage

Summer brings insect challenges to lawns, including fire ants, mosquitoes, chinch bugs, grub worms, mole crickets, fall armyworms, and sod webworms, all capable of causing significant damage.

Pictured above: A sod webworm.

To identify grub worm issues, look for increased activity from burrowing animals like moles or inspect the soil directly. Preventative insecticide applications against grubs, particularly from beetles like the Japanese and May/June beetles, are recommended around June, using products like Acelepryn.

Chinch bugs, problematic in St. Augustine grass, manifest as patchy, drought-like damage. Dylox 6.2 is effective against them. Sod webworms and fall armyworms chew on grass blades, leaving a transparent, “windowpane” appearance, with the latter distinguishable by a green or brown color and a black stripe.

Mole cricket damage is visible through their soil-uplifting tunnels and the brown, dying grass they leave behind.

Before using any insect control products, thoroughly read the label. For more on lawn insects, see Insect Identification.  Be sure to read labels thoroughly before application.

Natural Guard Spinosad – 1 Quart – Ready to Spray

Natural Guard Spinosad is an easy-to-use insect control solution that hooks up to the end of your garden hose. Available in a 1-quart bottle.

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6. Relax About Disease Control

Disease outbreaks in St. Augustine lawns are rare but can occur with summer overwatering, with gray leaf spot being the most common due to warm, wet conditions.

Grey Leaf In St Augustine Grass

Pictured above: Grey leaf spot in St. Augustine grass.

Preventative cultural practices from the St. Augustine Homeowner Maintenance Guide can help avoid diseases. These practices promote a resilient, healthy lawn.

For disease control, consider the recommended products below, ensuring to read their labels carefully. For more information on lawn diseases, refer to Identifying Common Lawn Diseases. Be sure to read labels thoroughly before application.

Heritage G Granular Fungicide

Heritage G Granular Fungicide is a broad-spectrum systemic fungicide that prevents and cures a variety of turfgrass diseases for up to 28 days. Available in 10 lb. and 30 lb. bags.

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Summer lawn care tips for your St. Augustine lawn are mostly about keeping it healthy and stress-free during the hot summer temperatures. This will help it continue to thrive when temperatures eventually cool down and we enter into the fall season. We will see you back here in the fall for our updated fall maintenance tips for St. Augustine.

And remember…if you want lawn care made simple, the Lawnifi Complete Subscription provides your lawn with what it needs during the current season and for years to come.

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