What Is The Best Slow Release Fertiliser On The UK Market?

Be it your lawn, garden, or flower bed – plants need to eat something good too once in a while. The good news is that there are plenty of fertilisers that can help you maintain strong, healthy plants. Unfortunately, the numerous types of fertilisers available only add to the confusion when looking for the best one.

If you’re just starting out, you might be tempted to go for quick – acting fertiliser. These come with the promise of immediate nourishment to your plants. But while quick release fertilisers are fast to take effect, this also means they are used up quicker and need to be applied more often. What’s more, the quick acting effect means alternating between periods of intensive nutrition followed by acute starvation – never a good thing for any plant.

Your best and safest bet for routine feeding is to use slow release fertilisers. These are designed to release a small, steady flow of nutrients over a longer time period. In addition to providing regular feeding for better overall health, slow release options eliminate the risk of fertiliser burns and are kinder to the environment.

Key Considerations When Buying Slow Release Fertilisers

Nutrient Needs

All fertilisers have the three key nutrients needed for healthy plant growth. These are Nitrogen, Phosphorous and Potassium. It’s important to choose a fertiliser with NPK ratings suitable for your intended purpose. Slow release options meant for lawns usually have higher Nitrogen ratios while fruiting and flowering fertilisers have higher phosphorous and potassium ratios. Make sure you pick the right one to get the best results.

The Best Slow Release Fertiliser Reviews

1. Miracle-Gro – Growmore Garden Plant Food Granules


If you’re looking for one of the most well rounded slow release fertilisers, Miracle Gro has just the thing. Their Growmore garden plant fertiliser is a general purpose food ideal for feeding fruits trees, flowering plants, shrubs, and vegetables. This feed is designed to provide an essential mix of nutrients for overall better plant growth and yield.

The Miracle-Gro – Growmore Garden Plant Food Granules come in a 3.5kg pack of a well balanced mix of nutrients. This includes Nitrogen that promotes healthy, lush leaves and strong growth, Phosphate that encourages vigorous root growth and potassium that improves the flowering and fruiting capabilities of plants. The granules are easy to use (just spread them by hand or dispenser). Each application lasts for 4 weeks.

What I like about it:

  • High quality, easy to use granules
  • Provides a balanced mix of essential nutrients
  • Large 3.5Kg pack

2. Eazifeed Bonemeal Slow Release Fertiliser


Are you just starting out a plant nursery? Or maybe you’re planting some trees and shrubs. If you want to get a massive headstart on the planting season, then you’ll need the Eazifeed Bonemeal Slow Release Fertiliser. This is a ready to use fertiliser that can be used as a root builder when planting anything around the garden.

In addition to giving plants a growth boost, the fertiliser also encourages rapid flowering and fruiting while keeping plants in tip top condition. This makes Bone Meal a general plant food for use on all types of crops. The best time to use the fertiliser is in autumn before first frost. It’s recommended that you wear gloves when sprinkling the Bone Meal and wash hands after use so you don’t contaminate food.

What I like about it:

  • Ideal for use as a root builder for new plants
  • Affordable price range
  • Can be used on fruits, vegetables and trees

3. Greenfingers Osmocote Plant Food Tablets


There’s nothing more confusing when using fertilisers than regular application. It’s hard to know when your regular is a bit overboard. What’s more, nobody wants to be applying fertilisers every week. If the thought of only one or two applications a year seems appealing, then you’ll need the ultimate controlled release action.

The Greenfingers Osmocote Plant Food Tablets come in 25 clean, user friendly tablets that are pushed directly into the soil or compost. What makes this fertiliser popular is that it has an ultra slow release action that feeds your plants consistently for a period of 6 months. This is all thanks to an advanced protective coating that offers accurate release without any chance of root burns.

What I like about it:

  • Ultra slow release action (up to 6 months)
  • 25 clean and easy to use tablets
  • Contains extra magnesium and other trace elements

4. Incredicrop Plant Fertiliser


Forget about flowers and lawns; if there’s a group of plants that absolutely require all their nutrients for healthy growth and yield, it has to be fruits and vegetables. The more nutrients and water your veggies have, the fatter your yield will be at the end of the growing season.

The Incredicrop Plant Fertiliser is a garden feed designed specifically for fruiting plants and vegetables. This cost effective option offers gardeners a boost of up to 400% more fruits and vegetables. Since it’s a controlled release, the fertiliser provides nutrients steadily for over 3 months meaning you only need one application every season. As a bonus, the feed incorporates unique double nitrogen technology that promotes vigorous, green leafy foliage for veggies.

What I like about it:

  • Purposefully designed for fruits and vegetables
  • Promises a growth boost by a factor of 4 (400%)
  • Unique double nitrogen technology

5. Gro-sure Slow Release Plant Food


Did you know that indoor plants also require proper nutrition? If you’re just looking for garden feed that you can use indoors, outdoors, and on virtually any plant or turf, then this is it right here. The Gro-sure Slow Release Plant Food comes in a big 2Kg pack full of small, easy to use granules.

Gro-sure Plant Food is specially formulated to make plants flourish thanks to a quick initial burst of energy when applied followed by 6 months of consistent nutrient release to last an entire growing season. The granules start acting as soon as they are activated by the warmer temperatures in soil. Gro-Sure included extra potassium in case you want to use the feed for flowering and fruiting plants.

What I like about it:

  • Comes in a large 2kg package
  • All purpose general slow release fertiliser (indoor and outdoor use)
  • Controlled release up to 6 months

Frequently Asked Questions

Q: Which plants like slow release fertiliser?

Moat plants like a slow release fertiliser. Slow release fertiliser gives plants a chance to absorb their nutrients slowly, over time, which mimics the natural way that plants absorb the goodness from the soil in nature, they don’t get a sudden burst of nutrients that they have to take in all in one go. Flowering plants in particular like their nutrients to be spread out slowly over time, as do many vegetables.

Slow release fertiliser can also remove the problems that can be caused by over feeding plants, such as nutrient burn. Depending on what type of plants you are feeding will depend on what type of fertiliser you should use, as each different plant has different nutrient needs – for example, turf and grass will require different nutrients than a flowering shrub or a vegetable plant.

When you are looking for slow release fertiliser, have a read about what sort of plant you are trying to fertilise before you decide on which type you are looking for.

Q: How to use slow release fertiliser?

When you are feeding your plants, it is often best to not overload the plants’ systems with a lot of nutrients all at once.

Slow release fertilisers leave the nutrients in the soil, allowing it to reach the plants in a slow, controlled manner, and also using a slow release fertiliser will allow the plants to take up the nutrients in a more natural manner.

Unlike some other fertilisers, you don’t have to worry too much about the state of the soil before you apply your fertiliser. You can jut sprinkle it around the plants and water it in, then sit back and await the results!

Different plants require different nutrients, so have a look into each plant and its requirements, the read the packaging of your chosen fertiliser to determine how it should be done.

Q: Is slow release fertiliser bad for dogs?

Some slow release fertilisers, such as organic rotted manure, will not harm your dog if they happen to munch on a mouthful of it (though it is not recommended to let them lick you afterwards!)

Other chemical fertilisers can cause harm, so you should always wait at least 24 hours before you let your dog loose in areas that you have fertilised.

Whichever type you use, you should always read the packaging and make sure it is safe for your furry friends – and the rest of the wildlife nearby – before you go scattering it on your lawn.


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