10 bestOrganic Slow Release Fertilizerof June 2025
112M consumers helped this year.
41% off
1
Gaia Green Organic 4-4-4 All Purpose Fertilizer 2kg
Gaia Green
9.9
2
Jobe's Organics Vegetable & Tomato Fertilizer Spikes, 50 Spikes
Jobe's Organics
9.8
3
Jobe’s Organics Fruit & Citrus Fertilizer with Biozome, 3-5-5 Organic Fast Acting Granular Fertilizer for All Fruit and Citrus Trees, 4 Pound Bag
Jobe's Organics
9.7
35% off
4
Espoma Co. GT4 4-Pound Garden-Tone 3-4-4 Plant Food
Espoma
9.5
9% off
5
Espoma Co. PT4 4-Pound Plant-Tone Organic 5-3-3 Food
Espoma
9.2
Other
Espoma Organic Plant-Tone 5-3-3 Natural & Organic All Purpose Plant Food; 4 lb. Bag; The Original Organic Fertilizer for All Flowers, Vegetables, Trees, and Shrubs. - Pack of 2
Dr. Earth Organic 5 Tomato, Vegetable & Herb Fertilizer Poly Bag
Espoma BTSP4 4 Lbs Bio-Tone Starter Plus 4-3-3
Gaia Green Organics Granulated Fertilizer for A Full Range of Annual and Perennial Plants, Flowers. (Power Bloom 2Kg)
6
Miracle-Gro Organics Pure Hen Manure Plant Food 3-1-2, 2kg
Miracle-Gro
9.0
7
Scotts Company Osmocote 274250 Outdoor and Indoor Smart Release Plant Food Bottle, 2-Pound
Osmocote
8.7
30% off
8
Dr. Earth 75557 1 lb 3-4-3 MINIS Acid Lovers Azalea, Camellia, Rhododendron and Maple Fertilizer
Dr. Earth
8.5
9
Espoma Co. RT4 4-Pound Rose-Tone 4-3-2 Plant Food
Espoma
8.2
10
Espoma Co. HT18 Holly Tone, 18-Pound
Espoma
7.9
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A Guide to Selecting the Best Organic Slow Release Fertilizer
Choosing the right organic slow-release fertilizer can make a big difference in the health and growth of your plants. These fertilizers provide nutrients gradually over time, which helps prevent overfeeding and reduces the need for frequent applications. When shopping for one, it's important to understand the key features that affect how the fertilizer works and how well it matches your gardening needs. By focusing on the main specifications, you can select a product that supports your plants' growth while being environmentally friendly.
Nutrient Ratio (N-P-K)
The nutrient ratio, often shown as three numbers like 5-3-2, represents the percentage of nitrogen (N), phosphorus (P), and potassium (K) in the fertilizer. Nitrogen helps with leafy growth, phosphorus supports root and flower development, and potassium aids overall plant health. Lower numbers are gentler and suitable for delicate plants or seedlings, while higher numbers are better for established plants needing a boost. To pick the right ratio, consider what your plants need most—leafy vegetables benefit from more nitrogen, while flowering plants may need more phosphorus.
Release Duration
Release duration tells you how long the fertilizer will continue to feed your plants after application. Some slow-release fertilizers work for a few weeks, while others can last several months. Shorter durations are good for fast-growing plants or if you want to adjust feeding more often, while longer durations are ideal for low-maintenance gardens or busy gardeners. Think about how often you want to reapply and how consistent you want the nutrient supply to be for your plants.
Source of Ingredients
Organic fertilizers can be made from a variety of natural materials like composted manure, bone meal, or plant-based ingredients. The source affects how quickly nutrients become available and how the fertilizer impacts soil health. Animal-based sources often provide more immediate nutrients, while plant-based or mineral sources may release nutrients more slowly. If you have preferences for vegan gardening or want to avoid certain animal products, check the ingredient list. Also, consider the environmental impact and sustainability of the sources.
Granule Size and Form
Fertilizers come in different forms such as pellets, granules, or powders. The size and form affect how easy the fertilizer is to apply and how evenly it spreads in the soil. Larger granules or pellets are easier to handle and less likely to blow away, making them good for outdoor gardens, while finer powders may be better for mixing into potting soil or for indoor plants. Choose a form that matches your gardening style and the type of plants you have.
Application Method
Some fertilizers are designed to be mixed into the soil, while others can be sprinkled on top or dissolved in water. The application method affects how quickly the nutrients reach the plant roots and how convenient the fertilizer is to use. If you prefer minimal effort, look for products that can be applied directly to the soil surface. For more targeted feeding, choose a fertilizer that can be mixed into the soil at planting time. Match the method to your gardening habits and the needs of your plants.
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