St Augustine grass requires fertilizer to grow and keep its dark green color. While big-box fertilizers are okay, we've found that they generally underperform for the price you pay. That's why we've reviewed the best pro-grade fertilizers for St Augustine grass.
This handy guide shows you our recommended picks for a granule, liquid, or environmentally-friendly fertilizer for St Augustine grass.
Best Weed and Feed Fertilizer: Ferti-lome St. Augustine Weed and Feed 15-0-4
Ferti-lome weed and feed supplies a St. Augustine lawn with nutrients and combats pesky weeds. Atrazine, a broad weed herbicide, is the active ingredient in the product. Ferti-lome Weed and Feed helps control crabgrass, sedge, and spurge. Late season applications kills chickweed, primrose, and rabbit tobacco. If you are looking for an all-in-one solution for fertilizer and weed control, Ferti-lome's product is the product you are looking to use.
Best Liquid Fertilizer: TurfGrassPro Blade Iron 15 – 0 – 0
TurfGrassPro Blade Iron 15 – 0 – 0 is the best liquid fertilizer for St Augustine grass. It is guaranteed to make your lawn green and ready for the growing season. Designed for warm-weather grasses, Ferromec's liquid fertilizer also contains iron and sulfur to help your turf reach peak vitality. Plan on using 2-8oz of product per 1,000 square feet of lawn. Many applications throughout the growing season will be needed. You can apply the product in smaller areas with a hand or backpack sprayer. Larger yards may need the use of an ATV or four-wheeler mounted sprayer.
Best Environmentally Friendly Fertilizer: Anugreen 16-0-2 Fertilizer
Anugreen's high nitrogen fertilizer greens up St. Augustine grass during any part of the summer. The product produces its fertilizer using renewable and recycled organic materials. Nitrogen goes into to the turf quickly. You can apply it several times during the heavy growth months. The fertilizer includes iron, potash, and sulfur in the fertilizer. These nutrients address many soil deficiencies. One 23-pound bag will provide ample coverage for up to 5,000 square feet of lawn. You can feel confident and comfortable in using a USDA certified eco-friendly product on your lawn.
ℹ️ Read more about St Augustine Grass.
What Nutrients Does St. Augustine Need?
Like many warm-weather grasses, St. Augustine needs an ample amount of nitrogen to thrive. Applying nitrogen to the turf will aid in growth, pigment development, and thickening.
Potassium allows the turf to withstand moderate amounts of stress and damage. It is not absorbed and metabolized as quickly as nitrogen. Potassium products should be applied 70-90 days before extreme heat or cold.
Other nutrients such as iron or phosphorus are only required when the soil has an identifiable deficiency. We recommended that the soil in your lawn be tested every three or four years to identify and nutrients that may be needed.
St. Augustine can grow in pH levels ranging from 5.0 to 8.5. If the soil's pH levels fall outside of the optimal range, sulfur, lime, or phosphorus will need to be applied. Iron deficiencies often exist in lawns that have a pH imbalance. If iron is needed, you may see yellow or brown spots appear on the lawn. You can find more information about soil pH levels and iron here.
How Often Should I fertilize?
Establishing a fertilization schedule is essential for St. Augustine grass. Your St. Augustine lawn will need three individual applications annually. Each application will cater to the lawn's nutritional needs depending on the time of year. As with any plan, it can be tweaked to fit your region or better fit your lawn's health and age. Your lawn will need three to four pounds of nitrogen and two rounds of potassium in the high growth season.
☀️ Early Summer (Early May – Mid June)
Apply one pound of a nitrogen-based fertilizer per 1,000 square feet of turf. If your soil needs phosphorus or iron added to help correct a pH deficiency, you should add it now. Depending on your soil's deficiency, it is important to apply nitrogen at a rate of one pound per 1,000 feet. Early season fertilization will help your lawn to “green up” as the turf emerges from dormancy.
☀️ Mid-Summer (Late June – Mid July)
Apply one pound of a nitrogen-based fertilizer per 1,000 square feet of turf. We recommended using a fertilizer that is high in potassium for the mid-summer application. Fertilizes with a composition of 10-0-10 or 15-0-15 are recommended. Potassium will fortify the lawn during the heat of the summer and will help to protect it from drought.
☀️ Late Summer (Late July – Late August)
Apply one pound of a nitrogen-based fertilizer per 1,000 square feet of turf. Once again, we recommend applying potassium during the last fertilization of the year. A fertilizer with a blend of 15-0-15 will provide your lawn with enough nitrogen and potassium. A late-season burst of potassium will provide extra fortification to your turf for winter.