10 Best Slow Release Fertilizer [Buyer Guide]
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If you’re growing plants, fruit, or veg – then it’s time to invest in some slow release fertilizer! Fertilizer is a useful “tool” to have for any home gardener, as it can give you a metaphoric helping hand when your plants need it the most. At Konservatory, we love donning our gardening boots and getting stuck into tending to our plants, and we love using slow release fertilizer to keep our plants nourished and healthy all year round.
Slow release fertilizer works slightly differently to your traditional fertilizer, as it works gradually over a 6-month period to feed nutrients to your plants. It’s great for home gardeners because it can save you time when you aren’t able to tend to your plants on a regular basis. It’s also great for temperamental weather here in the UK as it gives your plants the boost that they need. Overall, slow release fertilizer is fairly inexpensive, not only because you usually need a very small quantity, but it’s a product that you will use maximum 2-3 times a year, depending on the size of your garden. Of course, results aren’t guaranteed and you may find that some plants don’t respond to fertilizer as well as others, so it’s often a trial and error process – especially if you are dealing with a “rare” or delicate plant that is sensitive.
There are a variety of slow release fertilizers on the market, and we know that sometimes it can be a little overwhelming when you’re unsure which one will work best for you. Here at Konservatory, we pride ourselves on creating current, honest guides that cover products that vary in price, features and overall benefits.We’ve taken the time to review the 10 best slow release fertilizer’s on the market, taking into account their features and so much more. We’ve also included a detailed buyer guide at the bottom of this page, packed with an FAQ, further resources as well as an explainer video, too! You can also click through the products and purchase them yourself, if you really like the sound of them.
Gro-Sure 6 Month Slow Release Plant Food
The Gro-Sure 6 Month Slow Release Plant Food is a nutrient rich fertilizer that works after just one application. It provides and initial burst of energy, and then releases slowly for the following 6 months. You can have peace of mind that your plants will be nourished the whole season. It is ideal for use in containers, beds, boarders and hanging baskets, and can also work in smaller pots (indoor or outdoor plants).
Key Features:
Easy to use slow release fertilizer
Works for 6 months
Can be used on indoor and outdoor plants
A little goes a long way with the product
Specification:
Brand
Gro-Sure
Weight
2 kg
Consistency
Granules
Pros
It gives an initial burst of nutrients to bring life back into plants both indoors and outdoors
Cons
Granulated formula may not be to everyone's taste
Eazifeed Ready To Use Bonemeal
The Eazifeed Ready To Use Bonemeal is a easy to use fertilizer that can be used all over your garden, whether this is on bare soil or for potted plants. It is best used in Autumn to give your plants a winter boost, but can also be used closer to spring when planting new plants, giving them all the nutrients they need to thrive.
Key Features:
Powder formula fertilizer
Easy to use product
Can work in Autumn as well as Spring
Specification:
Brand
Eazifeed
Weight
0.75 kg
Consistency
Powder
Pros
Powder formula makes for easier absorption
Cons
Formula may not be to everyone's taste
Miracle-Gro Continuous Release Plant Food
The Miracle-Gro Continuous Release Plant Food is a nutrient rich fertilizer which can feed your plants for up to 6 months, meaning that you won’t have to regularly feed these – great if you have a busy schedule or a large garden. It works with all types of plants and is also suitable for fruits and vegetables.
Key Features:
Slow release nutrients
Easy to use and long-lasting formula
Great for all types of plants
Specification:
Brand
Miracle-Gro
Weight
2 kg
Consistency
Granules
Pros
Formula is highly absorbent and can work with nearly all outdoor plants as well as fruits and vegetables
Cons
Granule formula may not be to everyone's taste
Vitax Ltd Q4 Fertiliser
The Vitax Ltd Q4 Fertiliser is a bucket of pellet fertilizer which is perfect for plants, fruit, flowers, vegetables as well as brand-new laws. They can be applied throughout the growing season, and give your plants the extra boost that they need.
Key Features:
Pellet slow release fertilizer
Nutrients are packed into pellets for added impact
Easy to use - no mess
Specification:
Brand
Vitax
Weight
4.5 kg
Consistency
Pellet
Pros
Pellet form can be useful for those who don't want to deal with granules or powders
Cons
Pellets may not be to everyone's taste
Miracle - gro All Purpose Soluble Plant Food
The Miracle – gro All Purpose Soluble Plant Food is a water based slow release fertilizer that is fortified with nitrogen as well as other vitamins and minerals. This allows your plants, fruit and veg to grow and be fed at a regular rate, even through colder weather. You can use this in a watering can and tend to your plants in the autumn, or fresh in the spring time.
Key Features:
Soluble slow release fertilizer
Great for all types of plants, fruit and veg
Fortified with vitamins and nutrients
Specification:
Brand
Miracle-gro
Weight
1 kg
Consistency
Soluble
Pros
Soluble formula is ideal for those who want this type of fertilizer
Cons
Some may dislike a liquid formula due to it being slightly more messy
Miracle-Gro All Purpose Concentrated Liquid Plant Food
The Miracle-Gro All Purpose Concentrated Liquid Plant Food is a nutrient-rich fertilizer that is perfect for flowers and vegetables in pots of beds. It has a natural growth stimulant and guarantees visibly healthier plants in 7 days. It also acts as a slower release fertilizer which you can add throughout the season to keep your plants, fruits and vegetables nourished. It’s also child and pet friendly.
Key Features:
Liquid fertilizer
Can be used in water to feed your plants
Ideal for plants, veg and fruit in pots
Specification:
Brand
Miracle-gro
Weight
1 Kg
Consisteny
Liquid
Pros
Specifically designed for potted plants and vegetables
Cons
Formula may not be as strong as others on the market
Miracle-Gro Azalea, Camellia and Rhododendron Continuous Release Plant Food
The Miracle-Gro Azalea, Camellia and Rhododendron Continuous Release Plant Food is a rich and dense slow release fertilizer that is perfect for ericaceous plants. It feeds them for up to 6 months, meaning that you have peace of mind that they will survive throughout the season. This fertilizer is great for beds, borders, pots, containers and hanging baskets.
Key Features:
Pellet fertilizer
Ideal for potted plants
Easy to use - no mess
Specification:
Brand
Miracle-gro
Weight
1 kg
Consistency
Pellets
Pros
Pellets are easy to use, great for home gardeners who want something quick and reliable
Cons
Pellet formula may not be to everyone's taste
Gro-sure 6 Month Slow Release Plant Food
The Gro-sure 6 Month Slow Release Plant Food is an excellent general purpose food for use all around the garden. It provides a slow release of food to keep plants healthy and thriving for longer. It is formulated to feed plants for over 6 months, and gives you peace of mind that you don’t need to consistently feed your plants! Ideal for pots, hanging baskets and containers.
Key Features:
Granule fertilizer
Easy to use product
Slow release formula for up to 6 months
Specification:
Brand
Gro-sure
Weight
0.6 kg
Consistency
Granules
Pros
Smaller packet is great for those with smaller gardens
Cons
Size may not be big enough for some
JDS Hardware Miracle Gro Slow Release All Purpose Plant Food
The JDS Hardware Miracle Gro Slow Release All Purpose Plant Food is a nutrient dense fertilizer that comes in a “shaker” package, allowing you to evenly disperse pellets among your flowers, fruit and veg. Easy to use and requiring minimal maintenance, you can have complete clarity that your plants will be fed for up to 6 months. These pellets can be used on most garden plants, fruit, and vegetables.
Key Features:
Easy to use fertilizer
Pellet formula
"shaker" packaging
Specification:
Brand
JDS Hardware
Weight
1 kg
Consistency
Pellet
Pros
Shaker packaging is great for those who are looking for convenience
Cons
Packaging and pellets may not be to everyone's taste
Osmocote Controlled Release Plant Food Tablets
The Osmocote Controlled Release Plant Food Tablet is a set of 25 fertilizer tablets which are great for smaller gardens/areas – especially if you are new to the world of slow release fertilizers. The tablets have a controlled release action that feeds plants for up to 6 months. You simply push them straight into the compost and you’re good to go!
Key Features:
Protective coating tablets
Easy to use
Smaller quantity for smaller gardens
Specification:
Brand
Osmocote
Weight
0.025 kg (25 g)
Consistency
Pellet
Pros
Individual packs of fertilizer tablets are great for smaller areas
Cons
Quantity may not be enough for some
Summary
As you can see, there are so many types of slow release fertilizer to choose from. If you’re new to gardening, you’ll see that you’re definitely spoilt for choice! Slow release fertilizer is great for any home gardener, especially if you live in temperamental climates (like the UK).
Don’t think of slow release fertilizer as a cheat, instead, think of it as an extra boost for your plants, fruits and vegetables overall. If you’re still unsure on which fertilizer is going to be the best for you, have no fear! We’ve listed a few things for you to consider, as well as a detailed FAQ guide inclusive of a video and further reading.
If you enjoyed this guide, make sure to check out some of our others on the Konservatory website!
Consistency
When purchasing a slow release fertilizer, the biggest thing you have to consider is the consistency or formula of the fertilizer. Ultimately, all consistencies work to a similar rate, they’re just packaged differently and may work better depending on what your circumstances are. We’re going to break down the three main consistencies and list the pros and cons to help you make your decision!
Pellets
Pellets are often a similar consistency to dry pet food, and will vary in terms of shape but will roughly be the same size.
Pros:
- Pellets are great if want to get the fertilizer deep into the soil, as you can push them in as far as possible.
- They can also be useful if you have pets that may dig up the fertilizer, which defeats the object of using it in the first place
- It’s no mess, and child-friendly if you want to get your children involved with gardening
Cons:
- Absorption isn’t “instant” in comparison to other formulas
- Your plants may not respond as well to this consistency
Liquid
Liquids are either powders that you can mix with cold water, or thicker ‘serum’ consistencies
Pros:
- Instant absorption
- Soluble and can penetrate deep into the plant bed
Cons:
- Can be messy if dropped
- Plants may not respond well to this fertilizer
- You run the risk of over-watering
Granules/powder
Granules and powder are very similar in terms of consistency, and tend to have similar absorption qualities.
Pros:
- Easy to use and distribute
- Child and pet friendly
- A little goes a long way
Cons:
- If it doesn’t penetrate the soil deep enough, it can get blown away with tough weather
- Pets can dig this up if it’s not deep enough
We hope that this helps you with making your purchase, and if you have any questions – please don’t hesitate to reach out to us and we’d be happy to help.
FAQ
What is a good slow release fertilizer?
We’d be biased if we told you, but we believe the best fertilizer is one that works for you! Whether that’s a liquid formula for your plants in bulb planters or artificial hanging baskets, or a dry formula mixed into your multi purpose compost, you have to find what your plants respond best to. We recommend trying a range of slow release fertilizers.
How often should you use slow release fertilizer?
Twice a year – as most fertilizers work for up to 6 months. You may want to do a small top up after 4 months if your plants are looking lackluster, though. Always check with the brand and what they recommend.
How fast does slow release fertilizer work?
Usually within a week you should see a difference (very similar to lawn feed) but, it’s completely dependent on the plants you’re growing. Remember, this is slow release – so don’t panic if you don’t see results immediately as that isn’t the point of the product.
How does slow release fertilizer work?
Further reading: Tips for using slow release fertilizer