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5 Best Slow Release Fertilizers to Help your Garden Thrive! (2021 Review)

In this guide we’ll take a look at the best slow release fertilizers.
We’ve compared ingredients, ease of application, results and cost
to give you our top recommendations.

What is the Best Slow Release Fertilizer?

IMAGE RECOMMENDED PRODUCTSPRODUCT FEATURES
  • Best slow release fertilizer
  • 46% nitrogen content
  • Wide coverage
  • Best fertilizer for flowers
  • Released over 7 months
  • Double nitrogen content
  • Best for hanging plants
  • Release nutrients over 5-6 months
  • No waste
  • Best fertilizer for houseplants
  • Very easy to use
  • Great value for money
  • Best fertilizer for veggies
  • Double nitrogen technology
  • 400% more blooms

More Detailed Slow Release Fertilizer Reviews

URPril™ Slow Release Nitrogen Fertiliser

FEATURES RATING PRICE
FEATURES
  • Best slow release fertilizer
  • 46% nitrogen content
  • Wide coverage
OUR RATING
100
PRICE
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URPril™ Slow Release Nitrogen Fertiliser Review

The URPril Slow Release Nitrogen Fertilizer is the best slow release fertilizer for lawns on the market. This fertilizer is very versatile, soluble in water and suitable for use as an agricultural, forestry and general grass fertilizer.

This fertilizer has a wide coverage, with 1kg fertilizing an area of 200sqm. It can be applied as either a solid top dressing or a solution, and it’s made up of 46% nitrogen. It’ll give your garden the boost it needs.

If you’re looking for the best slow release lawn fertilizer on the market, the URPril Slow Release Nitrogen Fertilizer is our top recommendation!

Incredibloom Plant Fertiliser Controlled Slow Release

FEATURES RATING PRICE
FEATURES
  • Best fertilizer for flowers
  • Released over 7 months
  • Double nitrogen content
OUR RATING
95
PRICE
CHECK PRICE →

Incredibloom Plant Fertiliser Controlled Slow Release Review

The Incredibloom Plant Fertiliser is the best slow release fertilizer for flowers, allowing you to grow up to 4 times more flowers than you would without. Enjoy healthy and vigorous green foliage that’ll make your garden the envy of your neighbours!

This fertilizer is easy to use, producing results in just a single application. The fertilizer is released over 7 months, with the unique double nitrogen technology helping your flowers to thrive. It has the perfect NPK balance of 14-5-19.

If you’re looking for the best value slow release fertilizer for flowers, you can’t go wrong with the Incredibloom Plant Fertilizer.

Osmocote 50 Slow Release Fertiliser

FEATURES RATING PRICE
FEATURES
  • Best for hanging plants
  • Release nutrients over 5-6 months
  • No waste
OUR RATING
90
PRICE
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Osmocote 50 Slow Release Fertiliser Review

The Osmocote 50 Slow Release Fertilizer is the best slow release fertilizer for hanging plant baskets. This fertilizer is sold in individual tablets which makes it great value for money and ensures there’s no waste.

These tablets work straight down to the roots and contain a range of ingredients that your plants will love. They release essential nutrients slowly over 5-6 months to help your hanging plants thrive.

If you’re looking for the best slow release fertilizer for hanging plant baskets, the Osmocote 50 Slow Release Fertilizer is our top recommendation.

Jobe’s Houseplant Food Spikes

FEATURES RATING PRICE
FEATURES
  • Best fertilizer for houseplants
  • Very easy to use
  • Great value for money
OUR RATING
86
PRICE
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Jobe’s Houseplant Food Spikes Review

The Jobe’s Houseplant Food Spikes Fertilizer is the best organic slow release fertilizer and fantastic value for money. Suitable for indoor use, this fertilizer contains all the nutrients your precious houseplants need to thrive.

With the perfect balance of nitrogen, phosphorus and potassium, at 13-4-5, this fertilizer will have your house plants looking beautiful in no time at all. It’s exceptionally easy to use, simply insert the food spikes into the soil around your plant. The spikes will provide a continuous supply of nutrients down to the roots.

If you’re looking for the best slow release fertilizer for houseplants, the Jobe’s Houseplant Food Spikes are the ones for you!

Thompson & Morgan Slow Release Fertiliser

FEATURES RATING PRICE
FEATURES
  • Best fertilizer for veggies
  • Double nitrogen technology
  • 400% more blooms
OUR RATING
82
PRICE
CHECK PRICE →

Thompson & Morgan Slow Release Fertiliser Review

The Thompson & Morgan Slow Release Fertilizer is the best slow release fertilizer for vegetables. This multi purpose fertilizer will give you up to 400% more blooms and up to 400% more fruit and veggies!

Containing the perfect balance of plant nutrients for crop health, this fertilizer will boost all edible crops for the entire season with just one application. It comes in a 750g tub with unique double nitrogen technology to get your fruit and veggies feeling tip top. The nutrients are released over 3 months.

If you’re looking for the best slow release fertilizer for fruit and veggies, the Thompson & Morgan Slow Release Fertiliser is our top recommendation!

Slow Release Fertilizer Buyer’s Guide

A slow release fertilizer is a great purchase if you want to give your plants an extra boost of nutrients. This is especially important if you’re growing produce to eat or you pride yourself on your brightly coloured flowers. Fertilizer will give your plants a helping hand.

Slow release fertilizer is the easiest to use, helping to nourish your plants over the course of a few months. Not sure what to look for when it comes to the best slow release fertilizer? Check out this buyer’s guide.

Ingredients

The important thing to look at in your fertilizer are the N P K numbers which refers to the amount of nitrogen, phosphate and potassium. Spring fertilizers contain more nitrogen to encourage growth, while winter fertilizers have higher levels of phosphate and potassium.

Ease of Application

Slow release fertilizers tend to be the easiest to apply as they normally only need one application and this should see your plants through a few months. Spikes or tablets are the easiest, as these can simply be placed in the soil surrounding your plant and left to do their job.

Results

Although slow release fertilizers release their nutrients slowly, you should see results relatively quickly. Providing you use the right fertilizer for the season, your plants should be looking and feeling healthier within a few weeks. If you’re after immediate results, you’ll need to look for a fast acting fertilizer.

Slow Release Fertilizers FAQ

What is a slow release fertilizer and how does it work?

Slow release fertilizers need just one application and will feed your plants for a few months. The fertilizer enters the soil and is slowly broken down, with the nutrients absorbed by the plant. The nutrients aren’t immediately available, but your plant will enjoy the perfect balance of nutrients from spring until autumn.

How to use slow release fertilizer?

The best time to use slow release fertilizer is in the spring when the soil is warmer. This will help your plants to thrive in the summer months.

Slow release fertilizers come in a range of types, but they are most commonly in granular form. These can be applied dry by hand, then mixed and watered into the soil. Follow the manufacturer’s instructions when it comes to the amount of fertilizer to use on each area. Put on gloves before you touch the fertilizer.

If your fertilizer is soluble, dissolve it in the correct amount of water then apply using a watering can. For larger lawns, a knapsack sprayer will be more comfortable.

Drip feed or spike fertilizers can simply be inserted in the soil surrounding your plants.

Conclusion

A slow release fertilizer is one of the most low maintenance ways to tend to your lawn, plants and produce. Able to be added to the soil then left to work, these fertilizers are a great option if you don’t have hours of free time to spend in the garden! For its high nitrogen content, ease of application and value for money, the URPril Slow Release Nitrogen Fertilizer is our top recommendation.

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