When to Fertilize St. Augustine Grass

St. Augustine grass should be fertilized 2–4 times per year during the growing season. Treat St. Augustine with nitrogen fertilizer regularly, beginning 3 weeks after spring green-up and ending at the end of August.

In regions where St. Augustine does not go dormant in winter, continue to fertilize through fall. This may result in as many as 6 fertilizer applications to your St. Augustine lawn. These regular applications will keep your lawn green, healthy, and free of both weeds and disease.

When to fertilize St. Augustine grass

What is the Best Fertilizer for St. Augustine Grass?

To maintain a healthy St. Augustine lawn, choose a complete fertilizer that delivers a high quantity of nitrogen for blade growth, phosphorus for root development, and potassium for disease and cold resistance. This 16-4-8 fertilizer delivers the perfect balance of nutrients without risking nitrogen overload that could damage your lawn.

  • 16-4-8 fertilizer is perfectly balanced for St. Augustine lawns.
  • Milorganite is a natural, non-burning fertilizer great for use in the summer heat to promote greener St. Augustine.
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01/19/2022 12:08 am GMT

Because nitrogen fertilizer can burn lawns if applied during temperatures over 90℉ (32℃) or during periods of drought, at these times it is beneficial to use a natural, slow-release nitrogen fertilizer, such as Milorganite. In addition to being gentle on lawns, Milorganite contains iron, which encourages your St. Augustine to stay rich green in color.

St. Augustine Yearly Fertilizer Schedule

St. Augustine grass requires 2–4 pounds of nitrogen per 1,000 square feet annually. Regions with clay soil or a shorter growing season can thrive on 2 pounds of nitrogen yearly. Lawns planted in sandy soil, as well as lawns with longer growing seasons, need 4 pounds of nitrogen per year.

The following schedule contains ideal application rates using 16-4-8 fertilizer and Milorganite, so you don’t need to do any complex math. Simply measure your yard to find the square footage, and you’re ready to go.

  • March–May: 3 weeks after spring green-up, apply 3 pounds of 16-4-8 fertilizer per 1,000 square feet of lawn (each 18-pound bag will cover about 6,000 square feet).
  • June: Apply 6.25 pounds of 16-4-8 fertilizer per 1,000 square feet (each 18-pound bag will cover about 2,900 square feet). If your yard has clay soil, apply at a rate of 3 pounds per 1,000 square feet.
  • July: Apply 16 pounds of Milorganite per 1,000 square feet (1 bag for every 2,000 square feet). On clay soil, apply 8 pounds per 1,000 square feet (1 bag for every 4,000 square feet).
  • August: Apply 6.25 pounds of 16-4-8 fertilizer per 1,000 square feet. If your yard has clay soil, apply 3 pounds per 1,000 square feet.
  • September: If your St. Augustine goes dormant in winter, do not apply any fertilizer. If your lawn stays green year-round, apply at the same rates as August.
  • October–November: If your lawn goes dormant in winter, do not apply any fertilizer. If your lawn stays green year-round, apply fertilizer in October or November at the same rates as August. Do not apply in both months.
  • December–February: Do not apply any fertilizer.

If your lawn is in a region where St. Augustine remains green year-round, such as South Florida, make your first spring fertilizer application in late–March through early-May. This timing will provide fuel for your lawn to jumpstart its growing season.

By following this schedule you can easily fertilize your St. Augustine lawn for the best results. This system makes it easy to calculate how many pounds of fertilizer your need to buy and spread, resulting in less work on your part, and better results.

What Month Should You Fertilize St. Augustine Grass?

St. Augustine thrives from several fertilizer applications from spring through summer. Begin applying fertilizer in May. Then, apply fertilizer once per month through August.

  • Begin fertilizing St. Augustine in May.
  • Fertilize once-per-month through the summer, performing the final fertilizer application in August.
  • Applying fertilizer in small portions over the summer causes better growth, increases grass health, and allows the soil to absorb more nutrients.

By applying fertilizer in controlled portions over the course of the summer you feed your lawn gradually. This promotes even growth and prevents fertilizer burn that can kill your grass. Not only is an overload of fertilizer potentially harmful to your lawn, applying too much fertilizer at once causes it to wash out of your lawn before it can take effect. Several smaller applications yield better results from the same amount of fertilizer.

Should You Fertilize St. Augustine in Fall?

Only fertilize St. Augustine in fall in regions where St. Augustine remains green year-round. In these regions, such as South Florida, Arizona, and Southern California, make two fertilizer applications in the fall. The first application should be in September, the second in October or November.

  • Only fertilize St. Augustine in fall if your lawn does not go dormant (turn brown) in winter.
  • Do not apply fertilizer after August 31st if your lawn enters winter dormancy.
  • In applicable regions, fertilize St. Augustine twice in fall—September and October.
  • Do not apply any fertilizer December—February.

If your lawn goes dormant in winter, perform your last fertilizer application in August. It is detrimental to perform fall fertilizer applications to a yard that goes dormant in winter. Additionally, never fertilize dormant St. Augustine. it will not absorb the nutrients. Instead, you will invite an invasion of winter weeds.

What is the Best Time to Fertilize St. Augustine Grass?

Fertilize St. Augustine 2–4 times annually, between the beginning of May and the end of August. These applications should be evenly spaced, providing between 1/2 to 1 pound of nitrogen per application. Several smaller applications of fertilizer are preferable to fewer larger applications. This will prevent fertilizer burn and promote nutrient uptake by your grass.

The best type of fertilizer for St. Augustine lawns is a 16-4-8 fertilizer. It is balanced to promote growth and help your lawn resist cold and fungal diseases common to St. Augustine. To promote green color and prevent fertilizer burn in temperatures over 90℉ (32℃), apply a natural fertilizer with iron content. This simple schedule will make the application of fertilizer fast and simple, promoting a healthy lawn that’s easy to care for.

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