Best Slow-Release Garden Fertilizers of 2025

Steven Taylor Avatar
Steven Taylor
Last Updated: Jan 9, 2025

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Slow-release garden fertilizers are a great way to provide your plants with nutrients over an extended period of time. These fertilizers come in various forms, including granules, spikes, and pellets. They are designed to release nutrients slowly, allowing plants to absorb them gradually and reducing the risk of over-fertilization. Slow-release fertilizers are ideal for busy gardeners who don't have time for frequent applications and want to ensure their plants receive consistent nourishment. They are also an eco-friendly option, as they reduce the amount of fertilizer runoff that can harm the environment.

At a Glance: Our Top Picks

Schultz Vegetable Fertilizer for Tomatoes and Vegetables Cover #TOP 1
Schultz Vegetable Fertilizer for Tomatoes and Vegetables
ftb score rating icon 9.8
Jobe's Tree and Shrub Fertilizer Spikes Cover #TOP 2
Jobe's Tree and Shrub Fertilizer Spikes
ftb score rating icon 9.7
Schultz Slow-Release Bloom Fertilizer Cover #TOP 3
Schultz Slow-Release Bloom Fertilizer
ftb score rating icon 9.5

Top 10 Slow-Release Garden Fertilizers

Schultz Vegetable Fertilizer for Tomatoes and Vegetables

Schultz - SPF48100
Schultz Vegetable Fertilizer for Tomatoes and Vegetables Cover
Schultz 018062 Spf48100 Slow-Release Vegetable Fertilizer 3.5 Lbs

The Schultz 018062 SPF48100 Slow-Release Vegetable Fertilizer is perfect for growing delicious tomatoes and vegetables. The slow-release formula makes it easy to use and provides long-lasting nutrition for your plants. This fertilizer is a great choice for any gardener who wants to produce healthy and tasty vegetables.

What We Like
Easy to use
Slow-release formula provides long-lasting nutrition
Helps to produce healthy and tasty vegetables
#TOP 2

Jobe's Tree and Shrub Fertilizer Spikes

02610
Brown
160 Count
Jobe's Tree and Shrub Fertilizer Spikes Cover
Jobe’s Slow Release Tree and Shrub Fertilizer Spikes, Easy Plant Care for Oak, Maple, Dogwood, Boxwood, and Many More Acid Loving Trees and Shrubs, Bulk 160 Count

Jobe's Fertilizer Spikes are a convenient solution for nurturing your trees and shrubs. Each package contains 160 pre-measured spikes that deliver essential nutrients directly to the roots, ensuring healthy growth without the mess or hazards of traditional fertilizers. You only need to apply these spikes twice a year, in early spring and late fall, making plant care hassle-free. The unique formulation minimizes waste and eliminates the risk of over-fertilizing, giving you peace of mind while you care for your garden.

What We Like
Easy application
Pre-measured for convenience
Minimizes waste
No over-fertilizing risk
Suitable for various plants

Schultz Slow-Release Bloom Fertilizer

018065
Schultz Slow-Release Bloom Fertilizer Cover
Schultz 018065 Spf48270 Slow-Release Bloom Fertilizer 3.5 Lbs, 56 Ounce

Schultz Bloom Fertilizer is a 3.5 lbs slow-release garden fertilizer that is easy to use and requires no mixing. With a 12-24-12 nutrient ratio, this fertilizer provides the essential nutrients needed for blooming plants. The slow-release feature ensures a steady supply of nutrients over time, promoting healthy growth and vibrant blooms. Its convenient size makes it suitable for small to medium-sized gardens. Whether you're a beginner or an experienced gardener, Schultz Bloom Fertilizer is a reliable choice to enhance the beauty and vitality of your blooming plants.

What We Like
12-24-12 Nutrient Ratio
Slow-Release for steady nutrient supply
Easy to use, no mixing required

Milorganite Slow-Release Fertilizer

00608887475388
white
32 Pounds
Milorganite Slow-Release Fertilizer Cover
Milorganite All-Purpose Eco-Friendly Slow-Release Nitrogen 6-4-0 Fertilizer, 32 Pound Bag - for Lawns, Flowers, and Gardens

The Milorganite Slow-Release Fertilizer is an eco-friendly solution that aids in root development and contains non-staining iron, perfect for garden fertilization. This fertilizer has a fertilizer analysis of 6-4-0, and feeds your plants for up to 3 months, ensuring optimal growth and health.

What We Like
Eco-friendly solution
Aids in root development
Contains non-staining iron
Feeds for up to 3 months
#TOP 5

Organic Plant Magic - All-Purpose Fertilizer Granules

OPM-FGSPF-4Lb-FBA
Organic Plant Magic - All-Purpose Fertilizer Granules Cover
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 offers a new type of spreadable fertilizer granules that are easy to use and suitable for every plant. The granules can be added to the planting holes, mixed with soil, or spread on top of the soil by hand or spreader. It is a long-lasting formula that requires only once-a-month application, covering 1000 square feet with one 4 lb bag. The product contains essential plant nutrients, 55+ trace minerals, amino acids, humic acids, kelp, and beneficial GroBiotics, including mycorrhizae, to empower plants to express their full genetic potential, resulting in more vibrant colors and flavors.

What We Like
Easy to use and suitable for every plant
Long-lasting formula that requires once-a-month application
Contains essential plant nutrients, 55+ trace minerals, amino acids, humic acids, kelp, and beneficial GroBiotics
#TOP 6

Milorganite Eco-Friendly Fertilizer 6-4-0

Milorganite Eco-Friendly Fertilizer 6-4-0 Cover
Milorganite All-Purpose Eco-Friendly Slow-Release Nitrogen 6-4-0 Fertilizer, 5 Pound Bag - for Lawns, Flowers and Gardens

Milorganite Fertilizer 6-4-0 is a safe and effective choice for your lawn and garden. You won't have to worry about damaging your plants or lawn because it contains no harmful salts, preventing burns even in harsh weather. This fertilizer provides essential iron for a vibrant green color without staining your concrete. Its slow-release formula feeds your plants for up to 10 weeks, eliminating the need for frequent watering. Plus, it’s versatile enough for use in lawns, flowers, and vegetable gardens, ensuring your plants grow strong and healthy.

What We Like
No risk of burning
Stain-free iron delivery
Long-lasting nutrients
Versatile for all plants
#TOP 7

Schultz ACR 14-7-7 Plant Food

802697
Schultz ACR 14-7-7 Plant Food Cover
Schultz Azalea, Cameillia, Rhododendron, ACR 14-7-7 Slow Release Plant Food

Schultz Plant Food 14-7-7 is a convenient garden fertilizer that requires no mixing. Its slow-release formula ensures a steady supply of nutrients to your plants. Packed with micronutrients, this 3.5 lbs product promotes healthy growth. With a balanced 14-7-7 ratio, it caters to the specific needs of azaleas, camellias, and rhododendrons, making it ideal for your garden. Enjoy the ease of application and the long-lasting benefits of this plant food.

What We Like
No mixing required
Slow release formula
Micronutrients for plant health

RAINFLOW Organic Slow Release Fertilizer

RAINFLOW
LZH-Fertilizer-02
RAINFLOW Organic Slow Release Fertilizer Cover
RAINFLOW 11.28 OZ Slow Release Fertilizer - Organic Plant Food All Purpose Plant Fertilizer for Succulents Cactus Orchid Bonsai and All Other Plants Outdoor & Indoor Garden Fertilizer

RAINFLOW Plant Fertilizer is designed to support healthy growth for a variety of plants. With its balanced 14-13-13 nutrient formula, it provides essential nutrients that promote robust development. The organic composition ensures that nutrients are released slowly over 180 days, which means you won’t have to fertilize as often, saving you time and effort. This fertilizer is particularly beneficial for enhancing root development and improving soil structure, making it ideal for promoting flowering and fruiting in your plants. Whether you’re tending to orchids, succulents, or vegetables, this versatile option meets diverse gardening needs.

What We Like
Slow-release technology
Easy to apply
Works for various plants
Supports root and flower growth

Jobe’s Organics Evergreen Fertilizer Spikes

01210
Brown
8 Spikes
Jobe’s Organics Evergreen Fertilizer Spikes Cover
Jobe’s Organics Slow Release Evergreen Fertilizer Spikes, Easy Plant Care for Cypress, Arborvitae, Pine, Cedar, Boxwood, and Many More Acid Loving Trees and Shrubs, 8 Count

Jobe's Evergreen Fertilizer Spikes make plant care easy and efficient. Each package contains eight organic spikes designed to prevent waste and mess, ensuring a cleaner gardening experience. With an 8-2-2 NPK formulation, these spikes deliver a steady supply of essential nutrients right to the roots where your trees and shrubs need them most. Plus, they are completely free from synthetic chemicals and are USDA OMRI listed for organic gardening, giving you peace of mind about what you’re using. Simply apply them twice a year, and you can avoid the hassle of over-fertilizing with pre-measured spikes.

What We Like
Organic and chemical-free
Easy application
No waste or mess
Consistent nutrient supply
#TOP 10

EcoScraps Slow-Release Fertilizer, 45 lbs.

22311
45 lbs.
EcoScraps Slow-Release Fertilizer, 45 lbs. Cover
EcoScraps Slow-Release Fertilizer, Made with Recycled Nutrients and Organic Matter, Covers up to 2,500 sq. ft., 45 lbs.

EcoScraps Slow-Release Fertilizer is a high-performance product that provides excellent and long-lasting results for your lawn. It is made with organic matter and recycled nutrients, which makes it eco-friendly. This fertilizer can be used for your whole yard, including landscaped areas, shrubs, vegetables, trees, annuals, and perennials. When used as directed, it will not burn your lawn. Additionally, it covers up to 2,500 sq. ft.

What We Like
Long-lasting and high-performance
Made with organic matter and recycled nutrients
Suitable for entire yard including shrubs, vegetables, and perennials
Buying Guide Image

Everything You Need to Know About Slow-Release Garden Fertilizers

What is Slow-Release Fertilizer?

Slow-release fertilizers, also known as controlled-release fertilizers, are a type of plant food that gradually releases nutrients into the soil over a longer period of time than traditional fertilizers. This gradual release helps to prevent the rapid growth and subsequent flowering and fruiting of plants, allowing them to grow more slowly and steadily.

Why Use Slow-Release Fertilizers?

Slow-release fertilizers offer a number of benefits over traditional fertilizers. For one, they are more efficient, as the nutrients are released gradually over time, providing plants with a steady supply of food. This can help to promote healthier growth and reduce the need for frequent reapplication of fertilizer.

Slow-release fertilizers can also be more environmentally friendly than traditional fertilizers, as they release fewer nutrients into the soil at once. This can help to prevent soil erosion and leaching, as well as reducing the risk of nutrient runoff into waterways.

Choosing the Right Slow-Release Fertilizer

When choosing a slow-release fertilizer, there are a few key factors to consider. First, consider the type of plants you are growing, as different plants have different nutritional needs. Different slow-release fertilizers are formulated with different ratios of nutrients, so it's important to choose a fertilizer that is specifically designed for the plants you are growing.

Another important factor to consider is the length of time the fertilizer will release its nutrients. Some slow-release fertilizers release their nutrients over a period of just a few weeks, while others can release nutrients for several months. Choose a fertilizer with a release time that is appropriate for the growth cycle of the plants you are growing.

Finally, consider the type of slow-release fertilizer you want to use. There are two main types of slow-release fertilizers: coated and uncoated. Coated fertilizers have a protective coating that slowly breaks down over time, releasing the nutrients inside. Uncoated fertilizers, on the other hand, release their nutrients through a chemical reaction that occurs when the fertilizer comes into contact with moisture in the soil.

Conclusion

Slow-release fertilizers can be an effective way to provide plants with a steady supply of nutrients over a longer period of time. By choosing the right slow-release fertilizer for your plants and their growth cycle, you can help to promote healthy growth and reduce the need for frequent reapplication of fertilizer.

Frequently Asked Questions (FAQs)

1. Is slow-release fertilizer better?

Yes, slow-release fertilizer is generally considered better because it releases nutrients over a longer period, usually up to two months. In contrast, quick-release fertilizers provide nutrients for about two weeks. Slow-release fertilizers are particularly beneficial during the growing season as they provide a continuous supply of nutrients to plants.

2. Can you use slow-release fertilizer on vegetables?

Absolutely! Slow-release fertilizer can be used on all types of plants, including vegetables. It is suitable for vegetables, fruits, turf, shrubs, trees, and ornamental plants. When choosing a slow-release fertilizer, consider your specific needs and the requirements of your vegetable plants.

3. How often should you use slow-release fertilizer?

For vegetable gardens, it is recommended to fertilize the garden beds with a quick-release fertilizer once a month or a slow-release fertilizer once a season. Some gardeners also choose to supplement with a liquid-soluble plant food every one to two weeks for flowers and other plants.

4. Is slow-release fertilizer good for tomatoes?

Slow-release fertilizer can be beneficial for tomatoes, especially when grown in containers. However, it is important to note that slow-release pellets alone may not supply nutrients for the entire growing season. It is recommended to fertilize tomato plants with a water-soluble fertilizer about 6 weeks after planting, following the instructions on the package.

5. What are the disadvantages of slow-release fertilizer?

While slow-release fertilizers have their benefits, there are some disadvantages to consider. Nutrients are not immediately available to plants, and the effectiveness may be inhibited in cool soil. Organic-based slow-release fertilizers may require more water during hot periods, which can release nutrients more rapidly. Additionally, slow-release fertilizers can be more expensive than quick-release options, and it may take longer for plants to show green-up.

Editor's Notes

During our slow-release garden fertilizer research, we found 24 slow-release garden fertilizer products and shortlisted 10 quality products. We collected and analyzed 31,471 customer reviews through our big data system to write the slow-release garden fertilizers list. We found that most customers choose slow-release garden fertilizers with an average price of $18.72.

The slow-release garden fertilizers are available for purchase. We have researched hundreds of brands and picked the top brands of slow-release garden fertilizers, including Schultz, Jobe's Organics, Milorganite, Organic Plant Magic, RAINFLOW. The seller of top 1 product has received honest feedback from 385 consumers with an average rating of 4.7.

Written by
Steven Taylor Avatar

Steven Taylor grew up in a small town called Beaufort in South Carolina and his passion for building and woodworking has led him to master the latest garden gadgets. He always holds every chance to patch up or sand down his beloved garden. There are various novel technologies in his articles.