Only fertilize St. Augustine grass in winter if you live in a region where St. Augustine does not go dormant during the winter months. Do not apply fertilizer to dormant (brown) St. Augustine. If your grass remains green through winter, use 16-4-8 fertilizer. A single application that delivers 0.5 pounds of nitrogen per 1,000 square feet of lawn will provide enough nutrients to feed your lawn through winter.
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Top Winter Fertilizer for St. Augustine Lawns
16-4-8 fertilizer is the best choice for winter applications on St. Augustine lawns. It provides nitrogen to keep your green grass growing, phosphorus to maintain healthy roots, and potassium to help your lawn combat common winter diseases.
- This 16-4-8 fertilizer is ideal for St. Augustine lawns that do not enter winter dormancy.
- The 16% nitrogen content in 16-4-8 promotes green color and blade growth, even during short winter days.
- 16-4-8 contains 4% phosphorus, which keeps roots healthy during winter cold snaps.
- With 8% potassium by weight, 16-4-8 is excellent for helping St. Augustine fend off fungus and disease brought on by damp winter conditions.
Many regions where St. Augustine grass remains green through winter, such as South Florida, experience heavy winter rainfall. This can lead to diseases, grass rust, and fungus attacking your grass. The high potassium content in 16-4-8 fertilizer helps your St. Augustine resist these diseases.
When to Apply Fertilizer to St. Augustine in Winter
Not all St. Augustine lawns should be fertilized in winter. If your St. Augustine lawn enters dormancy (turns brown) in winter, you should make your final fertilizer application in September and resume fertilizing in March, 2 weeks after grass green-up. If you live in a region with mild winters where St. Augustine never enters dormancy, time your 16-4-8 fertilizer application for November or December.
- Do not fertilize from October through February in regions where St. Augustine goes dormant in winter.
- If your St. Augustine does not enter winter dormancy, make a single fertilizer application in November or December.
- Wait at least 6 weeks after your final fall fertilizer application before applying winter fertilizer.
If you fertilized your St. Augustine lawn in the fall, you risk burning your lawn with fertilizer overload by applying fertilizer in winter. Allow 6–8 weeks to pass after fall fertilizer application before spreading fertilizer in winter.
How Much Fertilizer to Apply to St. Augustine in Winter
The growth rate of St. Augustine grass decreases sharply in winter, even in temperate areas. As temperatures approach 60℉ (16℃), St. Augustine grass growth slows to a crawl. This means your St. Augustine grass has very low fertilizer needs. 0.5 pounds of nitrogen per 1,000 square feet is sufficient. This can be provided by spreading 3.1 pounds (3 pounds, 2 ounces) of 16-4-8 for every 1,000 square feet of grass.
- Find the square footage of your lawn before spreading fertilizer.
- Spread 3 pounds, 2 ounces of 16-4-8 fertilizer per 1,000 square feet of lawn.
- Use the weight and square footage system for fertilizer application instead of bag rates.
Fertilizer bag rates may recommend higher volumes of fertilizer, which is great for St. Augustine grass in summer or fall but is too much for a winter application. It’s important to reduce fertilizer usage in winter to give St. Augustine what it needs without damaging your yard through fertilizer overload.
How to Apply Fertilizer to St. Augustine in Winter
Use a broadcast spreader to distribute the proper amount of fertilizer evenly throughout your lawn. For best results, perform fertilization when the soil is moist but not extremely wet. Soil that has been saturated with water will shed excess water, meaning your fertilizer may run off when you attempt to water it in.
- Use a lawn spreader or hand spreader to apply fertilizer evenly throughout your lawn.
- Follow an east-west pattern when spreading fertilizer, then a north-south pattern. This ensures even coverage.
- Do not apply fertilizer in overly wet conditions.
- After fertilizing, water fertilizer into the soil with 15–30 minutes with the sprinkler.
Due to low winter temperatures, water evaporates much more slowly from your lawn. 0.25–0.5 inches of water will be sufficient for watering in your fertilizer. This can be accomplished in 15–30 minutes with the sprinkler. Then, your fertilizer will get to work right away feeding your St. Augustine.
What is the Best Fertilizer for St. Augustine Sod Installed in Winter?
Because the ground seldom freezes in regions where St. Augustine is grown, winter sod installations of St. Augustine are fairly common. However, as with established St. Augustine, you only need to fertilize your winter sod if it is green and growing. If it is, apply a lawn starter fertilizer at standard rates.
- Use this lawn starter fertilizer on green St. Augustine laid in winter.
- Do not apply any fertilizer to dormant St. Augustine sod.
- If your winter sod is dormant, wait until sod begins to green up in spring (February or March) before applying lawn starter fertilizer.
Applying fertilizer to dormant St. Augustine will be a waste of resources and effort. The dormant sod will not take up any of the fertilizer. There is a high chance the nutrients will wash out of the soil due to winter precipitation before spring arrives. Wait until the sod shows signs of life before applying your lawn starter.
How Do You Keep St Augustine Grass Green in Winter?
If you live in a region where winter temperatures dip below 55℉ (13℃), your St. Augustine will turn brown in winter regardless of how you fertilize and water it. This is because the cold temperatures trigger St. Augustine to enter dormancy until spring arrives. If you live in a warmer region, keep your St. Augustine green through winter with a single application of 16-4-8 fertilizer in November or December.
- If temperatures in your region go below 55℉ (13℃), in winter, St. Augustine will turn brown regardless of cultivation practices.
- If winter temperatures largely stay above 55℉ (13℃), you can keep St. Augustine lush in winter by applying 3.1 pounds of 16-4-8 fertilizer per 1,000 square feet. This application should be performed in November or December.
- To keep your lawn green in regions where St. Augustine enters winter dormancy, overseed with annual ryegrass in fall.
If you want to keep a St. Augustine lawn green in winter in colder regions, consider overseeding with annual ryegrass in fall. This grass will stay green through moderate winter temperatures and die off in summer while your St. Augustine flourishes.
How Do You Prepare St Augustine Grass for Winter?
The best way to prepare a St. Augustine lawn for winter is with an application of the best fall fertilizer for St. Augustine grass. Regardless of winter conditions, this fall fertilization helps your lawn store nutrients needed for a faster, greener, stronger spring.
- Keep St. Augustine healthy through winter by applying fertilizer in fall.
- Regardless of whether or not your St. Augustine goes dormant in winter, a fall fertilizer application contributes to a faster spring green-up.
- Never fertilize dormant St. Augustine grass. This can promote weed growth.
Fertilizing dormant St. Augustine does not contribute to a healthy lawn. The fertilizer will be wasted, or the nutrients will be stolen by invasive winter weeds such as Poa Annua (annual bluegrass) and chickweed.
Is it OK to Fertilize St. Augustine Grass in Winter?
Whether or not you should fertilize your St. Augustine lawn in winter depends on the conditions where you live. To determine your lawn’s winter needs, follow these simple rules:
- Do not fertilize in winter if your St. Augustine has entered dormancy (has turned brown).
- If your St. Augustine does not enter winter dormancy, perform one winter fertilizer application in November or December.
- Your winter fertilizer application should be 3.1 pounds of 16-4-8 fertilizer per 1,000 square feet of lawn.
- Wait at least 6 weeks after your final fall fertilizer application before spreading fertilizer in winter.
By following these tips you will promote a healthy St. Augustine lawn, keep your grass strong in winter, prevent fertilizer overload, discourage weeds, and prepare your grass for a vibrant spring.