16-4-8 fertilizer is the ideal fall fertilizer for St. Augustine grass. Spread your 16-4-8 fertilizer in September or October to deliver 1 pound of nitrogen per 1,000 square feet of lawn. This fall fertilizer application will promote fall shoot growth, encourage strong root formation before winter, and allow your St. Augustine grass to resist diseases during winter dormancy.
Table of Contents
What is the Best Fertilizer for St Augustine Grass in Fall?
This 16-4-8 fertilizer contains the optimal nutrient balance for fall applications on established St. Augustine grass lawns. 16-4-8 is a balanced fertilizer that contains a light amount of nitrogen with phosphorus and potassium. This allows you to feed your lawn without forcing blade growth that may weaken your grass before winter.
- Apply 16-4-8 fertilizer to established St. Augustine in the fall.
- Contains 16% nitrogen, to drive lush blade growth.
- 4% phosphorus content encourages grass to store energy in roots for winter.
- Includes 8% potassium, which helps St. Augustine resist disease and drought.
Phosphorus and potassium are essential nutrients when preparing St. Augustine grass for winter. Because 16-4-8 contains both these nutrients, it allows your lawn to survive the cold weather and shorter days of winter without damage. This leads to a brighter, faster green-up in spring.
When Should You Time Your Fall Fertilizer Application?
If you live in a region where St. Augustine enters dormancy (turns brown) in winter, apply your fall fertilizer in September. If you live in a region where St. Augustine stays green year-round (such as South Florida), then apply your fall fertilizer in October.
- Apply fall fertilizer in September if your St. Augustine grass goes dormant in winter.
- Spread fall fertilizer in October if your St. Augustine lawn remains green through winter.
- In regions with cold weather, apply fertilizer 4–6 weeks before the first average fall frost.
If temperatures dip low enough to cause frost where you live, time your fall fertilizer application at least 4 weeks before the first average fall frost. You can use this online tool to see when frost typically arrives in your region.
How Much Fertilizer Should You Apply to St. Augustine in Fall?
St. Augustine needs 1 pound of nitrogen per 1,000 square feet in fall. Because the “16” in 16-4-8 fertilizer means that the fertilizer is 16% nitrogen by weight, we can calculate the correct amount of fertilizer to spread. 6.25 pounds (6 pounds, 4 ounces) of 16-4-8 spread over 1,000 square feet will deliver 1 pound of nitrogen to the area.
- Find the square footage of your lawn using a tape measure and calculator.
- Apply 6.25 pounds of 16-4-8 fertilizer per 1,000 square feet of grass.
- Save your lawn square footage for future use.
Most lawn care guides recommend applying 1–1.5 pounds of nitrogen per 1,000 square feet, depending on the time of year. By keeping your lawn’s square footage saved somewhere, you can easily calculate how much fertilizer to use, no matter what the nitrogen content of your fertilizer is.
How to Apply Fertilizer to St. Augustine Grass in Fall
To spread your fall fertilizer evenly, measure out the required amount and load it into this broadcast spreader. A spreading tool helps distribute fertilizer evenly. Once your fertilizer is loaded into the spreader, traverse the yard first in an east-west pattern, then in a north-south pattern to ensure proper fertilizer coverage.
- Use a broadcast spreader to distribute fertilizer in large yards.
- For small yards, use this handheld spreader.
- Spread fertilizer in an east-west pattern, then a north-south pattern for even distribution.
- Water fertilizer into the soil to pull nutrients down to the root layer.
After your fertilizer has been spread, water it in within 30 minutes from a sprinkler system. This will dissolve the fertilizer granules and pull the nutrients down into the soil where they can feed grass roots.
What is the Best Fertilizer for Laying St. Augustine Sod in Fall?
If you have performed a fall installation of St. Augustine sod, it’s time to use a specialized lawn starter fertilizer. 16-4-8 may be the perfect formulation for established St. Augustine, but new sod needs a fertilizer with a higher phosphorus content. This will encourage your sod to take root quickly and survive the winter with ease.
- Use this lawn starter fertilizer for new St. Augustine sod installed in the fall.
- Lawn starter fertilizer has a much higher phosphorus content, which is needed to help sod take root.
- If desired, you can apply lawn starter fertilizer to bare, prepared soil before laying St. Augustine sod or plugs.
Lawn starter fertilizer is effective whether you’ve already laid new St. Augustine sod or if you’re just about to. You can spread a lawn starter on bare soil, then lay sod on top. This way, as soon as the sod makes contact with the soil below it will begin to draw in nutrients.
- Great starter fertilizer for new seed or sod.
- You can also use Pennington UltraGreen for overseeding or on an existing lawn.
- 5% Iron promotes a deep, thick, lush lawn.
Can You Use Weed and Feed on St Augustine Grass in Fall?
If your St. Augustine lawn is beset by fall weeds such as Poa Annua (annual bluegrass) or chickweed, you can apply a weed and feed product in the fall. Keep in mind, most weed and feed products that stop winter annuals like Poa Annua contain pre-emergent herbicides that kill weed seeds as they sprout, so they should be spread before winter annual weeds begin to show themselves in your lawn.
- Spread weed and feed in fall for St. Augustine lawns that are typically invaded by winter annuals.
- If possible, find a weed and feed with a nutrient balance similar to 16-4-8.
- Do not apply weed and feed to a newly sodded St. Augustine lawn.
If you have installed new St. Augustine from sod or grass plugs in the past 3 months, or plan to sod in the upcoming 3 months, do not use a weed and feed product. The herbicides in weed and feed can damage St. Augustine sod.
What Fall Fertilizer Should You Use on St. Augustine Grass?
To prepare St. Augustine grass for winter, apply a fall fertilizer that contains moderate amounts of nitrogen along with phosphorus and potassium. 16-4-8 fertilizer is perfect for fall applications in St. Augustine lawns because it delivers balanced nutrition that encourages growth, helps your lawn store energy for winter, and protects St. Augustine from disease.