Comparison: Best Slow Release Granular Organic Fertilizer (Updated | Nov 11th)
If you’re looking to give your garden a long-lasting boost without the harshness of chemicals, slow-release granular organic fertilizers are a game-changer. But with so many options out there, how do you know which one truly delivers? Whether you’re growing lush lawns, vibrant flowers, or juicy veggies, stick around. We’re breaking down the best picks to help your garden thrive naturally and sustainably.
Editor’s Choice
Best for a specific purpose
- Best for magic growth blend: Organic Plant Magic – Truly Organic™ Slow Release Granular Fertilizer : Long-Lasting Plant Food Granules – Indoor & Outdoor Flowers
- Best for 6-month smart release: Osmocote Smart-Release Plant Food Plus Outdoor & Indoor₁
- Best for eco balanced blend: True Organic All Purpose Plant Food – Organic Fertilizer for Fruits
- Best for standard 10-10-10: 10-10-10 Plant Fertilizer Slow Release – 10 10 10 All Purpose Granular Garden Fertilizer for Vegetables
- Best for value 10-10-10: 10-10-10 Plant Fertilizer Slow Release – 10 10 10 All Purpose Granular Garden Fertilizer for Vegetables
- Best for premium 10-10-10: 10-10-10 Plant Fertilizer Slow Release – 10 10 10 All Purpose Granular Garden Fertilizer for Vegetables
- Best for compact smart release: Osmocote Smart-Release Plant Food Plus Outdoor & Indoor₁
- Best for extended magic formula: Organic Plant Magic – Truly Organic™ Slow Release Granular Fertilizer: Long-Lasting Plant Food Granules – Indoor & Outdoor Flowers
- Best for lemon tree specialist: Organic Lemon Tree Fertilizer
- Best for 180-day organic feed: RAINFLOW 11.28 OZ Slow Release Fertilizer – Organic Plant Food All Purpose Plant Fertilizer for Succulents Cactus Orchid Bonsai and All Other Outdoor & Indoor Garden
Product Comparison: Best Slow Release Granular Organic Fertilizer
Magic Growth Blend
Organic Plant Magic – Truly Organic™ Slow Release Granular Fertilizer : Long-Lasting Plant Food Granules – Indoor & Outdoor Flowers, Vegetable Gardens, Fruit Trees, Shrubs, House Plants [One 4 lb Bag]
![Organic Plant Magic - Truly Organic™ Slow Release Granular Fertilizer : Long-Lasting Plant Food Granules - Indoor & Outdoor Flowers, Vegetable Gardens, Fruit Trees, Shrubs, House Plants [One 4 lb Bag]](https://m.media-amazon.com/images/I/51HyQUTD-WL._SL500_.jpg)
Organic Plant Magic
- New Spreadable Fertilizer Granules – Amazing Benefits that Plants & Customers LOVE!
- EASY & ALL PURPOSE – Simply grow healthy plants and beautiful gardens… Just add granules to planting holes, mix with soil, or top dress soil by hand or spreader. Works for everyone, every plant, everywhere, every time!
- LONG LASTING – Simply sprinkle a handful of Organic Plant Magic onto the soil of your plant once per month or more and water as normal for long lasting magical results! One 4 lb bag covers 1000 square feet.
- AMAZING GROWTH, COLOR, & FLAVOR – Empower your plants to express their full genetic potential. Get spectacular leaf, flower, fruit, veggie and herb production. Grow more vibrant color and flavor than ever before.
- BIOLOGY OVER CHEMICALS – This versatile all purpose granular blend is packed with every essential plant nutrient, plus 55+ trace minerals, amino acids, humic acids, kelp, and beneficial GroBiotics including mycorrhizae proven to provide everything your plants need to naturally grow their best!
6-Month Smart Release
Osmocote Smart-Release Plant Food Plus Outdoor & Indoor₁, Granular Fertilizer with 11 Essential Nutrients, 8 lbs.
Osmocote
- Osmocote Smart-Release Plant Food Plus Outdoor & Indoor₁ granular plant food contains 11 essential nutrients and feeds live plants up to 6 full months
- This fertilizer works with virtually all plant varieties and growing conditions
- Each granule is coated with a unique resin that controls nutritional release so plants get what they need when they need it
- Osmocote offers a no-burn pledge, when used as directed
- One 8 lb. container of Osmocote Smart-Release Plant Food Plus Outdoor & Indoor₁ covers up to 300 sq. ft.
Eco Balanced Blend
True Organic All Purpose Plant Food – Organic Fertilizer for Fruits, Vegetables, Flowers, and Herbs – 4lb Bag Covers 87 sq. ft.
True Organic
- Balanced Nutrition for All Plants: True Organic All Purpose Plant Food promotes abundant organic fruits, vegetables, flowers, herbs, and foliage with a well-rounded formula.
- Prevents Soil Depletion: Contains 5% nitrogen (3.75% slow-release), 4% phosphate, 5% potash, 4% calcium, and 1% sulfur to nourish plants and enrich soil.
- Exclusive Organic Blend: Includes seabird guano, shrimp and crab shell meal, soybean meal, and fish bone meal for a nutrient-packed, eco-friendly fertilizer.
- Versatile and Easy to Apply: Ideal for in-ground and container plants, this fertilizer is simple to apply monthly during the growing season for optimal growth.
- Flexible Sizing for Any Garden: Available in 4lb (covers 87 sq. ft.), 4.5lb shaker jug (97 sq. ft.), 8lb (174 sq. ft.), 12lb (261 sq. ft.), and 25lb (544 sq. ft.) bags to fit gardens of any size.
Standard 10-10-10
10-10-10 Plant Fertilizer Slow Release – 10 10 10 All Purpose Granular Garden Fertilizer for Vegetables, Tomato, Arborvitae, Shrubs, Rose, Flowers, Fruit, Fig Trees (1 Quart)
GARDENWISE
- 🌿 Balanced 10-10-10 Granular Fertilizer for Outdoor & Indoor Plants: All-purpose plant food with 10% Nitrogen, 10% Phosphorus, and 10% Potassium. Perfect for outdoor vegetable gardens, fruit trees, evergreens, shrubs, lawns, and flowers. Also great for potted plants and indoor gardening. One solution for all your plant needs!
- ⏳ Slow-Release Formula for Continuous Outdoor Feeding: Provides up to 8 weeks of sustained nutrition with fewer applications. Ideal for outdoor lawns, vegetable gardens, fruit trees, and flowering plants. Apply twice per season for gardens and three times per year for trees and shrubs. Less work, more growth!
- 🌼 Promotes Strong Roots, Lush Growth, and Vibrant Outdoor Blooms: Phosphorus supports root health, Nitrogen fuels lush green leaves, and Potassium enhances plant resilience. Perfect for outdoor flowers, tomatoes, peppers, roses, evergreens, and shrubs. Enjoy thriving plants, colorful blooms, and abundant harvests!
- 🌱 Easy-to-Apply Granules for Even Outdoor Coverage: Fine granules spread evenly for maximum soil absorption in outdoor gardens, lawns, and landscapes. Ideal for pines, oaks, banana trees, fig trees, and ornamentals. Just spread, water, and watch your outdoor garden flourish!
- ⚡ Quick-Release Nitrogen for Immediate Outdoor Results: Instant nitrogen boost for rapid growth, combined with slow-release feeding for lasting results. Perfect for outdoor grass lawns, evergreen trees, flowering plants, and vegetables. See your outdoor garden thrive quickly and sustainably!
Value 10-10-10
10-10-10 Plant Fertilizer Slow Release – 10 10 10 All Purpose Granular Garden Fertilizer for Vegetables, Tomato, Arborvitae, Shrubs, Rose, Flowers, Fruit, Fig Trees (2 QUARTS)
GARDENWISE
- 🌿 Balanced 10-10-10 Granular Fertilizer for Outdoor & Indoor Plants: All-purpose plant food with 10% Nitrogen, 10% Phosphorus, and 10% Potassium. Perfect for outdoor vegetable gardens, fruit trees, evergreens, shrubs, lawns, and flowers. Also great for potted plants and indoor gardening. One solution for all your plant needs!
- ⏳ Slow-Release Formula for Continuous Outdoor Feeding: Provides up to 8 weeks of sustained nutrition with fewer applications. Ideal for outdoor lawns, vegetable gardens, fruit trees, and flowering plants. Apply twice per season for gardens and three times per year for trees and shrubs. Less work, more growth!
- 🌼 Promotes Strong Roots, Lush Growth, and Vibrant Outdoor Blooms: Phosphorus supports root health, Nitrogen fuels lush green leaves, and Potassium enhances plant resilience. Perfect for outdoor flowers, tomatoes, peppers, roses, evergreens, and shrubs. Enjoy thriving plants, colorful blooms, and abundant harvests!
- 🌱 Easy-to-Apply Granules for Even Outdoor Coverage: Fine granules spread evenly for maximum soil absorption in outdoor gardens, lawns, and landscapes. Ideal for pines, oaks, banana trees, fig trees, and ornamentals. Just spread, water, and watch your outdoor garden flourish!
- ⚡ Quick-Release Nitrogen for Immediate Outdoor Results: Instant nitrogen boost for rapid growth, combined with slow-release feeding for lasting results. Perfect for outdoor grass lawns, evergreen trees, flowering plants, and vegetables. See your outdoor garden thrive quickly and sustainably!
Premium 10-10-10
10-10-10 Plant Fertilizer Slow Release – 10 10 10 All Purpose Granular Garden Fertilizer for Vegetables, Tomato, Arborvitae, Shrubs, Rose, Flowers, Fruit, Fig Trees (3 QUARTS)
GARDENWISE
- 🌿 Balanced 10-10-10 Granular Fertilizer for Outdoor & Indoor Plants: All-purpose plant food with 10% Nitrogen, 10% Phosphorus, and 10% Potassium. Perfect for outdoor vegetable gardens, fruit trees, evergreens, shrubs, lawns, and flowers. Also great for potted plants and indoor gardening. One solution for all your plant needs!
- ⏳ Slow-Release Formula for Continuous Outdoor Feeding: Provides up to 8 weeks of sustained nutrition with fewer applications. Ideal for outdoor lawns, vegetable gardens, fruit trees, and flowering plants. Apply twice per season for gardens and three times per year for trees and shrubs. Less work, more growth!
- 🌼 Promotes Strong Roots, Lush Growth, and Vibrant Outdoor Blooms: Phosphorus supports root health, Nitrogen fuels lush green leaves, and Potassium enhances plant resilience. Perfect for outdoor flowers, tomatoes, peppers, roses, evergreens, and shrubs. Enjoy thriving plants, colorful blooms, and abundant harvests!
- 🌱 Easy-to-Apply Granules for Even Outdoor Coverage: Fine granules spread evenly for maximum soil absorption in outdoor gardens, lawns, and landscapes. Ideal for pines, oaks, banana trees, fig trees, and ornamentals. Just spread, water, and watch your outdoor garden flourish!
- ⚡ Quick-Release Nitrogen for Immediate Outdoor Results: Instant nitrogen boost for rapid growth, combined with slow-release feeding for lasting results. Perfect for outdoor grass lawns, evergreen trees, flowering plants, and vegetables. See your outdoor garden thrive quickly and sustainably!
Compact Smart Release
Osmocote Smart-Release Plant Food Plus Outdoor & Indoor₁, Granular Fertilizer with 11 Essential Nutrients, 2 lbs.
Osmocote
- Osmocote Smart-Release Plant Food Plus Outdoor & Indoor₁ granular plant food contains 11 essential nutrients and feeds live plants up to 6 full months
- This fertilizer works with virtually all plant varieties and growing conditions
- Each granule is coated with a unique resin that controls nutritional release so plants get what they need when they need it
- Osmocote offers a no-burn pledge, when used as directed
- One 2 lb. container of Osmocote Smart-Release Plant Food Plus Outdoor & Indoor₁ covers up to 75 sq. ft.
Extended Magic Formula
Organic Plant Magic – Truly Organic™ Slow Release Granular Fertilizer: Long-Lasting Plant Food Granules – Indoor & Outdoor Flowers, Vegetable Gardens, Fruit Trees, Shrubs, House Plants (Two 4 lb Bags)
Organic Plant Magic
- New Spreadable Fertilizer Granules – Amazing Benefits that Plants & Customers LOVE!
- EASY & ALL PURPOSE – Simply grow healthy plants and beautiful gardens… Just add granules to planting holes, mix with soil, or top dress soil by hand or spreader. Works for everyone, every plant, everywhere, every time!
- LONG LASTING – Simply sprinkle a handful of Organic Plant Magic onto the soil of your plant once per month or more and water as normal for long lasting magical results! One 4 lb bag covers 1000 square feet.
- AMAZING GROWTH, COLOR, & FLAVOR – Empower your plants to express their full genetic potential. Get spectacular leaf, flower, fruit, veggie and herb production. Grow more vibrant color and flavor than ever before.
- BIOLOGY OVER CHEMICALS – This versatile all purpose granular blend is packed with every essential plant nutrient, plus 55+ trace minerals, amino acids, humic acids, kelp, and beneficial GroBiotics including mycorrhizae proven to provide everything your plants need to naturally grow their best!
Lemon Tree Specialist
Organic Lemon Tree Fertilizer, Slow Release Dry Granular Fertilizer for Lemon and Citrus Trees – 1 Pound (16 Oz)
TPS NUTRIENTS
- Specifically formulated to meet the nutritional needs of lemon trees, providing balanced nourishment for optimal fruit production and plant health.
- Slow-release granules deliver nutrients gradually, ensuring continuous feeding and long-lasting benefits for lemon trees.
- Enriched with Kelp and trace elements to support overall plant vigor and resilience to environmental stressors.
180-Day Organic Feed
RAINFLOW 11.28 OZ Slow Release Fertilizer – Organic Plant Food All Purpose Plant Fertilizer for Succulents Cactus Orchid Bonsai and All Other Outdoor & Indoor Garden
RAINFLOW
- Balanced Nutrient Formula: This slow release fertilizer contains 14-13-13 NPK to provide comprehensive nutritional support to promote healthy plant growth and is suitable for various gardening and agricultural needs
- Organic Fertilizer for Plants: Our organic plant food is made with a special slow release technology that releases nutrients for up to 180 days, reducing the frequency of fertiliser applications and saving time and effort
- Slow Release Plant Fertilizer: This garden fertilizer not only enhances plant root development and loosens the soil, but also promotes flowering and fruiting, giving plants nutrition and protection
- Versatile Applications: Our all purpose plant fertilizer is suitable for orchids, succulents, cacti, vegetables and many other flowers and plants, providing balanced nutrients suitable for different kinds of plants and gardening projects
- Easy to Use: The granular fertilizer is easy to spread and mix, suitable for home gardening and large scale planting. Beginners and gardening enthusiasts can easily get started without complicated fertilizer application operations
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product.
Buying Guide
FAQs
What should I look for when choosing a slow‑release granular fertilizer?
Focus on the nutrient balance (N‑P‑K), the presence of organic additives like kelp or mycorrhizae, and the release duration. Also consider coverage area per bag, whether the formula is certified organic, and any extra benefits such as trace minerals or a no‑burn guarantee.
How does Organic Plant Magic compare to Osmocote Smart‑Release?
Organic Plant Magic is a fully organic blend with 55+ trace minerals, amino acids, humic acids, and GroBiotics, while Osmocote relies on a resin coating for controlled release and contains synthetic nutrients. Organic Plant Magic offers broader micronutrient diversity, whereas Osmocote provides up to six months of feeding with a precise release schedule.
Is a balanced 10‑10‑10 fertilizer a good choice for my garden?
A 10‑10‑10 formula delivers equal parts nitrogen, phosphorus, and potassium, which works well for general-purpose feeding of lawns, vegetables, and ornamental plants. However, if you need higher nitrogen for rapid leaf growth or lower phosphorus for fruiting crops, a specialized blend like the True Organic All‑Purpose (5‑3.75‑5) may be more effective.
What are the advantages of a fertilizer with mycorrhizae and GroBiotics?
Mycorrhizae form symbiotic relationships with plant roots, improving nutrient and water uptake, while GroBiotics contain beneficial microbes that enhance soil health. These biological components can boost plant vigor, increase resistance to stress, and often lead to better flavor and color in fruits and vegetables.
How do coverage rates affect the value of each product?
Coverage determines how many square feet a bag can treat; for example, Organic Plant Magic’s 4‑lb bag covers about 1,000 sq ft, giving it a lower cost per area than Osmocote’s 8‑lb bag covering 300 sq ft. Calculating cost per square foot helps you compare true value, especially for larger gardens.
Can I use the same fertilizer for indoor and outdoor plants?
Many of the listed products, such as Osmocote Smart‑Release and the 10‑10‑10 blends, are formulated for both indoor and outdoor use, but indoor plants may benefit from lower release rates to avoid over‑fertilization. Always follow label directions and consider using a smaller amount for container plants.
What is the benefit of a slow‑release formula versus a quick‑release one?
Slow‑release fertilizers supply nutrients gradually over weeks or months, reducing the risk of nutrient burn and the need for frequent re‑applications. Quick‑release options give an immediate boost but may require more frequent dosing and careful monitoring to prevent excess buildup.
How important are trace minerals and organic matter in a fertilizer?
Trace minerals like iron, zinc, and manganese are essential for enzymatic functions and overall plant health, while organic matter improves soil structure and water retention. Fertilizers that include these components, such as Organic Plant Magic and True Organic All‑Purpose, can enhance long‑term soil fertility beyond basic N‑P‑K nutrition.