Best Slow Release High Nitrogen Outdoor Plant Food of 2026

Last updated on 03/04/2026
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1
Osmocote PrePlant Plant Food 1kg Slow Release Fertiliser For Season-Long Plant Nutrition 17-9-10+2MgO+TE
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Osmocote PrePlant Plant Food 1kg Slow Release Fertiliser For Season-Long Plant Nutrition 17-9-10+2MgO+TE

Generic
Why we love it
  • Supplies nutrients all crop cycle.
  • Ideal base fertilizer for media.
  • Easy to use.
Main Highlights
  • All nutrients supplied during all crop cycle
  • Specially suited for use as a base fertilizer mixed into growing media
  • High NPK content
  • Full trace element package
  • Easy to use
  • NPK 17+9+10+2MgO+TE
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9.8
Exceptional
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9.8
Exceptional
Generic

Osmocote PrePlant Plant Food 1kg Slow Release Fertiliser For Season-Long Plant Nutrition 17-9-10+2MgO+TE

Why we love it
  • Supplies nutrients all crop cycle.
  • Ideal base fertilizer for media.
  • Easy to use.
Main Highlights
  • All nutrients supplied during all crop cycle
  • Specially suited for use as a base fertilizer mixed into growing media
  • High NPK content
  • Full trace element package
  • Easy to use
  • NPK 17+9+10+2MgO+TE
Show More
Value for Money
2
Grow More Plant Food Fertilizer - 2kg All Purpose 6-Month Slow Release Plant Food Granules for Outdoor Plants with Topline Card. Garden Fertiliser for Plants, Vegetables or Houseplants
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Grow More Plant Food Fertilizer - 2kg All Purpose 6-Month Slow Release Plant Food Granules for Outdoor Plants with Topline Card. Garden Fertiliser for Plants, Vegetables or Houseplants

Topline
Why we love it
  • Feeds for 6 months.
  • Boosts flowers and roots.
  • Suitable for all plants.
Main Highlights
  • Indoor or outdoor garden plants feed bulk buy contains: 1 x 2kg Grow more All Purpose 6-months Plant Food with unique Topline Thank You Card. All-Purpose Slow Release Plant Food for use all around the garden. Providing a slow release of food to keep plants healthy and thriving for longer.
  • Slow Release Plant Food granules is a blend of slow release and fast acting nutrients to keep plants healthy, and thriving for longer. Is a great food for flowers, fruits, vegetables, roses, shrubs and trees in containers.
  • The fast acting nutrients boost flowers and root growth, whilst the slow release nutrients feed the plant for 6 months and promote a healthy foliage and long lasting blooms. Suitable for all plants and great for baskets and containers.
  • A blend of slow-releasing granules, plus fast-acting plant food providing nutrients when plants need it most.
  • The plant pellets can be premixed with compost, top soil before planting, added to the planting hole area or used as a top dressing. Water in the granules to activate.
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9.6
Superb
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9.6
Superb
Topline

Grow More Plant Food Fertilizer - 2kg All Purpose 6-Month Slow Release Plant Food Granules for Outdoor Plants with Topline Card. Garden Fertiliser for Plants, Vegetables or Houseplants

Why we love it
  • Feeds for 6 months.
  • Boosts flowers and roots.
  • Suitable for all plants.
Main Highlights
  • Indoor or outdoor garden plants feed bulk buy contains: 1 x 2kg Grow more All Purpose 6-months Plant Food with unique Topline Thank You Card. All-Purpose Slow Release Plant Food for use all around the garden. Providing a slow release of food to keep plants healthy and thriving for longer.
  • Slow Release Plant Food granules is a blend of slow release and fast acting nutrients to keep plants healthy, and thriving for longer. Is a great food for flowers, fruits, vegetables, roses, shrubs and trees in containers.
  • The fast acting nutrients boost flowers and root growth, whilst the slow release nutrients feed the plant for 6 months and promote a healthy foliage and long lasting blooms. Suitable for all plants and great for baskets and containers.
  • A blend of slow-releasing granules, plus fast-acting plant food providing nutrients when plants need it most.
  • The plant pellets can be premixed with compost, top soil before planting, added to the planting hole area or used as a top dressing. Water in the granules to activate.
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3
Westland Boost Slow Release Plant Food 2kg
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Westland Boost Slow Release Plant Food 2kg

Westland
7% Off
Why we love it
  • Boosts root growth effectively.
  • Promotes lush green foliage.
  • Enhances flowering and resilience.
Main Highlights
  • Instant nutrients and bio-stimulant will boost root growth
  • Targeted nitrogen feed will give lush green foliage
  • Slow release feed for 6-moth nutrient supply helps boost disease resistance
  • High potassium levels will promote flowering, fruit production and plant resilience
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9.5
Superb
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9.5
Superb
Westland

Westland Boost Slow Release Plant Food 2kg

7% Off
Why we love it
  • Boosts root growth effectively.
  • Promotes lush green foliage.
  • Enhances flowering and resilience.
Main Highlights
  • Instant nutrients and bio-stimulant will boost root growth
  • Targeted nitrogen feed will give lush green foliage
  • Slow release feed for 6-moth nutrient supply helps boost disease resistance
  • High potassium levels will promote flowering, fruit production and plant resilience
Show More
4
Gro-Sure 6 Month Slow Release Plant Food 1.1kg + 50% Extra Free
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Gro-Sure 6 Month Slow Release Plant Food 1.1kg + 50% Extra Free

Gro-Sure
Why we love it
  • Longer blooms for garden beauty.
  • Dual action for healthy plants.
  • Quick boost for vibrant growth.
Main Highlights
  • Longer lasting blooms
  • Dual action granules keep plants thriving for longer
  • Instant boost for flowers and root growth
  • 6 months feed
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9.4
Superb
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9.4
Superb
Gro-Sure

Gro-Sure 6 Month Slow Release Plant Food 1.1kg + 50% Extra Free

Why we love it
  • Longer blooms for garden beauty.
  • Dual action for healthy plants.
  • Quick boost for vibrant growth.
Main Highlights
  • Longer lasting blooms
  • Dual action granules keep plants thriving for longer
  • Instant boost for flowers and root growth
  • 6 months feed
Show More
5
Gro-Sure All Purpose Slow Release Plant Food Dual Action Granules for Long-Lasting Blooms Slow Release Nutrients Ideal for Flowers, Fruits & Vegetables Feeds for 6 Months (1.65Kg Box)
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Gro-Sure All Purpose Slow Release Plant Food Dual Action Granules for Long-Lasting Blooms Slow Release Nutrients Ideal for Flowers, Fruits & Vegetables Feeds for 6 Months (1.65Kg Box)

TOP SAVER
Why we love it
  • Long-lasting blooms enhance beauty.
  • Versatile for all plant types.
  • Easy to use for gardening.
Main Highlights
  • 🌱 Long-Lasting Blooms: Promotes vibrant, long-lasting flowers by supporting healthy root systems and foliage growth.
  • 🌱 Ideal for All Plants: Suitable for a wide range of plants including flowers, fruits, vegetables, trees, and shrubs, ensuring versatility in your garden.
  • 🌱 Perfect for Baskets & Containers: Specially designed for pots, tubs, hanging baskets, and garden beds, making it a great choice for all types of gardening.
  • 🌱 Easy to Use: Can be premixed with compost, added to planting holes, or used as a top dressing, offering a simple solution for feeding plants.
  • 🌱 Boosts Root & Flower Growth: The fast-acting nutrients provide an instant boost to roots and flowers, helping plants grow stronger and healthier from the start.
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9.3
Superb
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9.3
Superb
TOP SAVER

Gro-Sure All Purpose Slow Release Plant Food Dual Action Granules for Long-Lasting Blooms Slow Release Nutrients Ideal for Flowers, Fruits & Vegetables Feeds for 6 Months (1.65Kg Box)

Why we love it
  • Long-lasting blooms enhance beauty.
  • Versatile for all plant types.
  • Easy to use for gardening.
Main Highlights
  • 🌱 Long-Lasting Blooms: Promotes vibrant, long-lasting flowers by supporting healthy root systems and foliage growth.
  • 🌱 Ideal for All Plants: Suitable for a wide range of plants including flowers, fruits, vegetables, trees, and shrubs, ensuring versatility in your garden.
  • 🌱 Perfect for Baskets & Containers: Specially designed for pots, tubs, hanging baskets, and garden beds, making it a great choice for all types of gardening.
  • 🌱 Easy to Use: Can be premixed with compost, added to planting holes, or used as a top dressing, offering a simple solution for feeding plants.
  • 🌱 Boosts Root & Flower Growth: The fast-acting nutrients provide an instant boost to roots and flowers, helping plants grow stronger and healthier from the start.
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6
Miracle-Gro Premium All Purpose Continuous Release Plant Food, 2 kg, White
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Miracle-Gro Premium All Purpose Continuous Release Plant Food, 2 kg, White

Miracle-Gro
Why we love it
  • Controls nutrient release optimally.
  • One-season feeding convenience.
  • Promotes strong, healthy plants.
Main Highlights
  • Temperature controlled coating that regulates the release of nutrients when the conditions are right for feeding
  • One application at the start of spring will feed your plants for the whole season, removing the need for regular feeding
  • Contains essential nutrients for strong healthy plants
  • Model number: 121069
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9.3
Superb
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9.3
Superb
Miracle-Gro

Miracle-Gro Premium All Purpose Continuous Release Plant Food, 2 kg, White

Why we love it
  • Controls nutrient release optimally.
  • One-season feeding convenience.
  • Promotes strong, healthy plants.
Main Highlights
  • Temperature controlled coating that regulates the release of nutrients when the conditions are right for feeding
  • One application at the start of spring will feed your plants for the whole season, removing the need for regular feeding
  • Contains essential nutrients for strong healthy plants
  • Model number: 121069
Show More
7
Vitax Bonemeal, Organic Fertiliser, Slow Release, Encourages Healthy Root Development, For All Plants, Vegetables And Fruit Trees- 5Kg Tub
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Vitax Bonemeal, Organic Fertiliser, Slow Release, Encourages Healthy Root Development, For All Plants, Vegetables And Fruit Trees- 5Kg Tub

Vitax Ltd
Why we love it
  • Slow release of nutrients.
  • Perfect for various plants.
  • Supplies key nutrients.
Main Highlights
  • SLOW-RELEASE NUTRIENTS: Vitax Bonemeal Organic Fertiliser provides a gradual release of essential nutrients, making it perfect for sustained nourishment of a wide variety of crops and plants.
  • PROMOTES ROOT DEVELOPMENT: Vitax Bonemeal Fertiliser encourages healthy root growth, crucial for robust plant development and overall health.
  • VERSATILE APPLICATION: Ideal for bulbs, herbaceous plants, shrubs, roses, fruit trees, and strawberries. This organic fetaliser can be used before sowing or planting, as a top dressing in spring, and around fruit trees and bushes in autumn.
  • 100% ORGANIC: Made from sterilised bonemeal, offering organic nourishment while supporting environmental sustainability.
  • HIGH IN PHOSPHATE AND NITROGEN - Vitax Bonemeal is high in phosphate and nitrgen, essential tfor strong, healthy and disease resistent plants and flowers
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9.2
Superb
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9.2
Superb
Vitax Ltd

Vitax Bonemeal, Organic Fertiliser, Slow Release, Encourages Healthy Root Development, For All Plants, Vegetables And Fruit Trees- 5Kg Tub

Why we love it
  • Slow release of nutrients.
  • Perfect for various plants.
  • Supplies key nutrients.
Main Highlights
  • SLOW-RELEASE NUTRIENTS: Vitax Bonemeal Organic Fertiliser provides a gradual release of essential nutrients, making it perfect for sustained nourishment of a wide variety of crops and plants.
  • PROMOTES ROOT DEVELOPMENT: Vitax Bonemeal Fertiliser encourages healthy root growth, crucial for robust plant development and overall health.
  • VERSATILE APPLICATION: Ideal for bulbs, herbaceous plants, shrubs, roses, fruit trees, and strawberries. This organic fetaliser can be used before sowing or planting, as a top dressing in spring, and around fruit trees and bushes in autumn.
  • 100% ORGANIC: Made from sterilised bonemeal, offering organic nourishment while supporting environmental sustainability.
  • HIGH IN PHOSPHATE AND NITROGEN - Vitax Bonemeal is high in phosphate and nitrgen, essential tfor strong, healthy and disease resistent plants and flowers
Show More
8
Gro-Sure 6 Month Slow Release Plant Food, 1.1 kg
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Gro-Sure 6 Month Slow Release Plant Food, 1.1 kg

Gro-Sure
Why we love it
  • Continuous plant nourishment for six months.
  • Suitable for all non-ericaceous plants.
  • Adaptable to varied plant environments.
Main Highlights
  • Just one application feeds your plants with a fast acting initial burst of energy then provides 6 months continuous feed to provide your plants with additional nutrients for the whole growing season
  • Suitable for use with all non-ericaceous plants
  • Ideal for use in pots, containers, beds, boarders and hanging baskets
  • Fertiliser NPK: 12-7-19 with micro nutrients
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9.1
Superb
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9.1
Superb
Gro-Sure

Gro-Sure 6 Month Slow Release Plant Food, 1.1 kg

Why we love it
  • Continuous plant nourishment for six months.
  • Suitable for all non-ericaceous plants.
  • Adaptable to varied plant environments.
Main Highlights
  • Just one application feeds your plants with a fast acting initial burst of energy then provides 6 months continuous feed to provide your plants with additional nutrients for the whole growing season
  • Suitable for use with all non-ericaceous plants
  • Ideal for use in pots, containers, beds, boarders and hanging baskets
  • Fertiliser NPK: 12-7-19 with micro nutrients
Show More
9
Miracle-Gro All Purpose Continuous Release Plant Food 900g | Feeds Plants for Up to 6 Months | Ideal for Pots, Beds & Containers | Slow-Release Fertiliser for Healthy Growth
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Miracle-Gro All Purpose Continuous Release Plant Food 900g | Feeds Plants for Up to 6 Months | Ideal for Pots, Beds & Containers | Slow-Release Fertiliser for Healthy Growth

MURIEL BARGAINS
Why we love it
  • Long-lasting nourishment for plants.
  • Supports vibrant growth and health.
  • Easy application for all plants.
Main Highlights
  • Slow-release plant food for long-lasting nourishment – designed to feed plants gradually for up to 6 months.
  • Supports vibrant flowers, healthy foliage & strong roots – delivers balanced nutrients for consistent growth.
  • Ideal for use in pots, containers, borders & hanging baskets – suitable for both indoor and outdoor plants.
  • One application feeds the entire season – reduces the need for frequent feeding or reapplication.
  • Moisture control technology – helps plants absorb nutrients efficiently and prevents waste.
  • Perfect for all types of flowers, shrubs, and edibles – versatile formula supports a wide range of plant types.
  • Easy-to-use granular format – simply mix into the soil at planting or apply to the soil surface.
  • 900g pack treats up to 26 average-sized plants – excellent value for routine garden maintenance.
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8.9
Excellent
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8.9
Excellent
MURIEL BARGAINS

Miracle-Gro All Purpose Continuous Release Plant Food 900g | Feeds Plants for Up to 6 Months | Ideal for Pots, Beds & Containers | Slow-Release Fertiliser for Healthy Growth

Why we love it
  • Long-lasting nourishment for plants.
  • Supports vibrant growth and health.
  • Easy application for all plants.
Main Highlights
  • Slow-release plant food for long-lasting nourishment – designed to feed plants gradually for up to 6 months.
  • Supports vibrant flowers, healthy foliage & strong roots – delivers balanced nutrients for consistent growth.
  • Ideal for use in pots, containers, borders & hanging baskets – suitable for both indoor and outdoor plants.
  • One application feeds the entire season – reduces the need for frequent feeding or reapplication.
  • Moisture control technology – helps plants absorb nutrients efficiently and prevents waste.
  • Perfect for all types of flowers, shrubs, and edibles – versatile formula supports a wide range of plant types.
  • Easy-to-use granular format – simply mix into the soil at planting or apply to the soil surface.
  • 900g pack treats up to 26 average-sized plants – excellent value for routine garden maintenance.
Show More
10
Bamboo Fertilizer Super Food Slow Release Osmocote Pro 5-6M Potassium Nitrogen (500g)
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Bamboo Fertilizer Super Food Slow Release Osmocote Pro 5-6M Potassium Nitrogen (500g)

Generic
Why we love it
  • Slow-release for long-lasting growth.
  • Balanced nutrients promote plant health.
  • Versatile for various plant types.
Main Highlights
  • ✓ Slow-Release Technology – Feeds plants gradually over 5–6 months for long-lasting growth
  • ✓ Balanced Formula – Ideal NPK ratio of 15-9-12 promotes root strength, leaf health, and flowering
  • ✓ High Nutrient Efficiency – Provides essential macro and micronutrients without leaching or burn
  • ✓ Versatile Use – Perfect for bamboo, trees, shrubs, conifers, and ornamental bedding plants
  • ✓ Professional Quality – Proven Osmocote technology trusted by landscapers and horticulturists
  • ✓ Mess-Free Granules – Clean, easy application with no strong odors or liquid handling required
Show More
8.8
Excellent
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8.8
Excellent
Generic

Bamboo Fertilizer Super Food Slow Release Osmocote Pro 5-6M Potassium Nitrogen (500g)

Why we love it
  • Slow-release for long-lasting growth.
  • Balanced nutrients promote plant health.
  • Versatile for various plant types.
Main Highlights
  • ✓ Slow-Release Technology – Feeds plants gradually over 5–6 months for long-lasting growth
  • ✓ Balanced Formula – Ideal NPK ratio of 15-9-12 promotes root strength, leaf health, and flowering
  • ✓ High Nutrient Efficiency – Provides essential macro and micronutrients without leaching or burn
  • ✓ Versatile Use – Perfect for bamboo, trees, shrubs, conifers, and ornamental bedding plants
  • ✓ Professional Quality – Proven Osmocote technology trusted by landscapers and horticulturists
  • ✓ Mess-Free Granules – Clean, easy application with no strong odors or liquid handling required
Show More

We scanned 663 products

We reviewed these offers relevant to the Slow Release High Nitrogen Outdoor Plant Food within online retailers such as Amazon, eBay and other local retailers, ensuring we covered all major brands and models. The products we selected come from trusted brands like Generic, Topline, Westland, Gro-Sure, TOP SAVER, Miracle-Gro, Vitax Ltd, MURIEL BARGAINS, all of which have a reputation for consistently delivering high-quality products that users love and innovative approaches for function & design.
For the best Slow Release High Nitrogen Outdoor Plant Food in the market, we considered we took a deep dive into 3316 online reviews , focusing on elements like user satisfaction, performance in real-world conditions, and long-term reliability. Our ranking also evaluates each review’s relevancy, authenticity, up-to-dateness and depth so that the comparison is more sound.

We concluded that: