Best Organic Fertilizers for Healthy St Augustine Grass Lawns 2025
Maintaining a lush St Augustine grass lawn requires the right fertilizer, especially one that supports organic growing principles. This guide covers top-rated organic fertilizers designed to nurture your grass naturally, improve soil health, and promote vigorous growth. Below is a summary table of selected products that offer balanced nutrition and weed control suited for St Augustine grass.
| Product | Brand | Type | Special Features |
|---|---|---|---|
| Organic Plant Magic Slow Release Granular Lawn Fertilizer | Organic Plant Magic | Granular | Contains GroBiotics, safe for pets and kids, all-purpose organic care |
| Fertilome St. Augustine Weed & Feed 15-0-4 | ferti-lome | Granular with Herbicide | Pre/post-emergent weed control with tailored fertilizer |
| Advanced 16-4-8 Balanced NPK Liquid Fertilizer | Simple Lawn Solutions | Liquid | Includes seaweed and fish extracts, easy spray application |
| LESCO 50 lb. St. Augustine Grass Weed and Feed | LESCO | Granular Slow-Release | Slow-release, safe for Floratam, controls weeds and feeds |
| The Andersons Professional PGF Complete 16-4-8 Fertilizer | The Andersons | Granular with Humic Acid | MUtech coated slow release nitrogen, contains humic acid |
Organic Plant Magic Truly Organic Slow Release Granular
Organic Plant Magic offers a truly organic slow-release granular fertilizer specially formulated for various grasses including St Augustine. The product features GroBiotics®, a blend of amino and humic acids combined with beneficial biology, which promotes healthy microbial activity in the soil. This proprietary blend helps improve nutrient uptake and stimulates soil health over time.
Designed as an all-purpose lawn treatment, it supports maintenance, recovery, and new sod installation across all climates and seasons. The formula is safe for children, pets, and the environment, with carefully selected non-toxic ingredients ensuring no harm. It enhances grass density and color naturally without harmful chemicals, making it an ideal choice for organic lawn care enthusiasts seeking sustainable growth.
Fertilome St. Augustine Weed & Feed 15-0-4
This weed and feed fertilizer from Fertilome combines a pre-emergent and post-emergent herbicide with a 15-0-4 fertilizer ratio designed specifically for St Augustine grass. It offers effective weed control along with balanced feeding that promotes turf health and vigor.
While excellent for managing broadleaf weeds and common lawn pests, it is important to note that this product should not be used on Bermuda or northern grasses. The specific nutrient blend ensures St Augustine lawns receive nitrogen and potassium while avoiding phosphorus, which can be less needed in some established lawns. This product suits homeowners seeking targeted weed control coupled with lawn nutrition.
Advanced 16-4-8 Balanced NPK Liquid Fertilizer Spray
Simple Lawn Solutionseasy-to-use liquid fertilizer with an advanced balanced NPK ratio of 16-4-8, ideal for spring and summer feeding of any grass type including St Augustine. The formula also includes seaweed and fish extracts, which contribute trace minerals and natural growth enhancers that support strong root development and green coloration.
Its liquid form allows for uniform coverage via spray, making application straightforward and less labor-intensive. This product nourishes the grass rapidly while supplying essential nitrogen for greening and potassium for stress resistance. It suits users who prefer liquid nutrition delivery with an organic-inspired approach.
LESCO 50 lb. St. Augustine Grass Weed and Feed
The LESCO 50 lb. fertilizer includes a 17-0-17 formulation with 30% poly-coated sulfur-coated urea, delivering a slow-release nitrogen source designed especially for St Augustine grass, including the Floratam variety. This nutrient delivery lasts up to 8 weeks, reducing frequent applications and managing lawn growth effectively.
Its weed control capability ensures healthy turf by eliminating invasive species while boosting grass development with potassium and nitrogen. The product performs best when applied to wet turf, then allowed to dry for optimal nutrient uptake. This option caters to those seeking professional-grade weed control combined with slow-release feeding tailored for St Augustine lawns.
The Andersons Professional PGF Complete 16-4-8 Fertilizer with Humic Acid
This professional-grade fertilizer from The Andersons features a 16-4-8 nutrient ratio with incorporated 7% humic acid for enhanced soil and turf health. The MUtech coated slow-release nitrogen technology ensures steady nutrient release while protecting against premature loss from mowing or weather.
The fine particle size facilitates even distribution and quick absorption, contributing to uniform turf growth. The humic acid component enriches soil microbial life, improving nutrient uptake efficiency and reducing fertilizer requirements over time. This product fits users desiring advanced slow-release technology combined with soil-enriching additives for durable St Augustine lawns.
Buying Guide for Organic Fertilizers for St Augustine Grass
Selecting the best organic fertilizer for St Augustine grass depends on several factors to ensure optimal lawn health and environmental safety.
Nutrient Composition and Ratio
Look for balanced nitrogen (N), phosphorus (P), and potassium (K) ratios suited to St Augustine’s needs. Nitrogen promotes green growth, potassium boosts stress tolerance, while phosphorus supports root development. Often, phosphorus content may be low or omitted if soil tests indicate sufficient levels.
Organic Certification and Ingredients
Choose fertilizers with certified organic ingredients or natural additives like humic acids, amino acids, seaweed extracts, and beneficial microbes. These enhance soil biology, improve nutrient availability, and promote sustainable lawn care.
Application Method and Timing
Granular fertilizers provide longer feeding duration but require proper watering. Liquid fertilizers offer faster nutrient uptake and easy application but may need more frequent use. Apply during active growth seasons (spring and summer) and avoid over-fertilization to prevent burn or environmental run-off.
Weed and Pest Control Features
Some fertilizers incorporate pre/post-emergent herbicides, which can simplify lawn maintenance but may contain non-organic chemicals. Consider your preference for purely organic inputs versus combined feed-and-weed solutions.
Safety and Environmental Impact
Opt for fertilizers formulated to be safe for children, pets, and local wildlife. Avoid harsh synthetic chemicals and look for slow-release formulas that minimize nutrient leaching and pollution.
Grass Type and Regional Suitability
Ensure the fertilizer is formulated for warm-season grasses like St Augustine and is appropriate for your climate region. Some products may exclude Northern grasses or Bermuda types and specify regional applicability.
With these factors in mind, choosing an organic fertilizer will support your St Augustine grass’s vibrant, healthy, and environmentally friendly lawn.