Written by Terry Smith

Our site is reader supported so when you click a link to Amazon we may earn an affiliate commission.

Best Soil Compost Reviewed

This article was last updated on August 7th, 2021 at 12:58 am

If you were to ask me what the single most important gardening product to buy is, I think I would have to say compost. The ratio of cost to results alone is enough for me to comfortably say that compost is something every gardener should be using, and if they’re not, they should definitely start.

The benefits of using a good soil compost are numerous, but to name a few we could point out that compost helps to retain moisture, adds valuable and essential nutrients for your plants to feed on, and even helps to fight off pests and disease. With this in mind, surely it is time that you bought a bag or two of one of the best soil compost products, and transformed your garden into a fertile paradise for your plants.

On this page you will find reviews of the best soil compost products that you can order online at the moment, and inks to buy should you like the sound of them. Enjoy reading!

Comparison table: Best Soil Compost Reviewed

ProductWhat We ThinkPrice

Miracle-Gro All Purpose Compost

  • New premium compost with 3 patends that caters the needs of all young and mature potted plants...
  • Smart release system feeds the plants for up to 6 months with all the vital minerals...
  • Fibre Smart Technology ensures the optimum balance of air and water for strong roots and healthier plants...
  • Waterlock technology absorbs 25% more water than ordinary compost

J Arthur Bowers Multi Purpose Compost

J Arthur Bowers Multi Purpose Compost 100L Bale

  • Feeds for upto 6 weeks
  • Suitable for pots, baskets
  • Great for Shrubs, plants
  • Multi purpose compost
  • Contains Nitrogen, Phosphate & Potassium

Baltic Worm Worm Castings - Multi Purpose Fertiliser

  • ✔️MULTIPURPOSE FERTILISER. Perfect for germination
  • ✔️SHOP WITH CONFIDENCE. You can be confident

Westland Houseplant Potting Compost Mix

  • This is a specialist blend that can be used by anybody who wants a strong and healthier plant that...
  • The added SERAMIS granules do a fantastic job at regulating the plants water intake to ensure optimum water and...
  • The added perlite in this mix generates airflow and drainage resulting in healthier root development which internal improves the...
  • This 4L bag will fill a 14cm Pot.
  • Package may vary

Green Brokers Organic All Purpose Potting Compost

  • All purpose expandable potting compost for in and outdoor use
  • Organic and enriched with nutrients to boost plant development and health
  • Small lightweight, easy to carry pack
  • No more carrying around heavy
  • Perfect for smaller households or flats with limited storage space

Westland 50L Multi-Purpose Compost with John Innes

Westland 50L Multi-Purpose Compost with John Innes, Brown

  • Suitable for all life stages of plants
  • Develops stronger plants
  • Produces more flowers, more vibrancy and longer plant life


Most of us have a houseplant or two, and one of the best ways to keep them strong and healthy is to use a potting compost mix. One of the very best composts for this is Westland’s houseplant potting compost mix, which has been designed specifically to promote growth and the sustained well-being of your indoor plants. I have to admit that after reading a few negative comments about this product having plant damaging insects inside, I was a bit trepid, but I’m happy to say that there was nothing wrong with the compost we received, and not a bug in sight. I did notice that most of these comments were from over two years ago, so it might have just been a bad batch to have got sent out.

This potting compost is available in either 4 lite or 8 litre bags, and will fill either one or two 14cm pots; respectively.  It contains all the nutrients that your houseplants need, wood fibre for improved drainage and air circulation, and perlite. All of these promote strong root development and this helps the plants to thrive.

Westland’s houseplant potting compost also contains ‘SERAMIS’ granules. These granules are a type of clay, and their purpose is to absorb water and then release it at a slower rate so that your plants get a steady stream of moisture and nutrients.

This is a good product, and I like the fact you can buy it in smaller bags and don’t end up with a load leftover if you only have a couple of houseplants to repot. You do have to be careful not to overwater your plants when using this potting compost as it retains water well, but this is a good thing rather than a negative.

Multi-purpose soil composts are extremely popular due to their versatility. You can use them for containers, beds, and borders, and for a wide range of different plants; from shrubs to crops. Of course, if you are using this compost with multiple plants, you need a lot of it and this product definitely ticks that box with a bag containing a 100 litre bale. This makes it quite heavy, so it’s a good thing you can get it delivered right to your door.

J Arthur Bowers multi-purpose compost has a light and airy feel to it, which I’ve always taken as a good sign for such products, and the vast majority of customers are giving it very positive feedback.

For environmentally friendly purposes, this product has been formulated with reduced peat, which is good news for the planet and all the species of creatures that are affected by peat mining. The big three: nitrogen, potassium, and phosphate are included in the J Arthur Bowers compost, providing your plants and crops with the main sources of nutrition that they need. These three nutrients are what make up the majority of fertilisers (in differing ratios), so you can rest assured that this compost is only doing good things for your garden.

Mixing this compost into your soil will provide your plants with food for up to six weeks, as well as helping with moisture retention, and strengthening roots. A good all-rounder, the J Arthur Bowers Multi-purpose soil compost is a good pick for gardens with a lot of variety when it comes to plant selection.

More and more people are becoming environmentally aware, and due to this are only interested in using organic composts like this one from green Brokers. A multi-purpose soil compost that can be used for both indoor and outdoor applications, this compact brick will expand to give you 10 lites worth of top-notch potting compost once water is added to it, but for larger gardens you can also buy this product in larger sizes such as 20, 40, and 75 litres.

The dehydrated state that it arrives in keeps the size and weight of the product to a minimum and this is a handy thing when it comes to storage. As already mentioned, this is an organic product, but it has also been enriched with extra nutrients to ensure your pants are getting what they need to thrive. It is peat free too, so you can pat yourself on the back knowing that you have contributed a little to helping the planet.

Because it is organic, and therefore there are no chemicals that could harm pets, it makes this product a good choice for putting in a rabbit run, so you can scoop it back up later with the ‘extra ingredients’ provided with by your rabbit’s dirty doings. Rabbit droppings make an excellent addition to this already great compost, adding even more nutritional value for your plants to feed on. 

I did notice that this soil compost dried out faster than some other products if used outside, so I would keep an eye on that if you decide to use this product. Indoors it wasn’t the case though, and it needed watering about as often as normal.  

I would say this particular product is perfect for growing seedlings and cuttings, and does a great job of helping them get established. The fact that it is all organic and peat free is just a bonus.

If you’re not an experienced gardener, you might be surprised by the term ‘added John Innes’, but not to worry, it doesn’t mean there are anyone’s remains in there. John Innes refers to a specific formula that was developed in the 1930s, and combines peat, sterilised loam, and sometimes other materials. There are actually a number of different formulas that share the name John Innes, and these are often numbered, such as John Innes No.1, etc.

So, now we know what has been added to Westland’s all purpose compost, what we need to know is- is it any good? The answer is definitely yes. This compost works really well on most things, but for certain crops such as tomatoes and chilies, it doesn’t seem to produce the same positive results. For the vast majority of plants, vegetables, and fruit though, it serves its purpose very well.

This compost retains water well, and along with; nutrients for the plants to feed on. It is particularly good for seedlings, and really helps them to get established well in the soil. This 50 litre pack costs just under 10 pounds online, which is a little more expensive than some of the other products we reviewed, but Westland is a well-known brand, so that is to be expected to some degree.

Westland says that this mix of their Westland+ formula and John Innes formula will feed your plants well for up to five weeks, and then you can just treat them again with fertiliser every 2-3 weeks after that. 

You can use this compost for both indoor and outdoor applications, and it works as well in pots as it does mixed with soil and laid in your beds and borders. Basically, it’s another good all-round product for multiple purposes.

Miracle-Gro are well known for producing some of the best gardening products available and are frequently featured in ‘best of’ lists. Their all purpose compost is yet another fantastic product that is well worth a closer look if you are in the market for a growing medium that can be applied to a wide range of plants, both in the garden, and in the house.

One thing I’ve always liked about Miracle-Gro is that they are always trying to innovate, with new patents for formulas and technologies. This product alone features three of these patents; their smart release system, fibre smart technology, and water lock technology.

The smart release system is very clever, and uses temperature and humidity levels to postpone the releasing of stored moisture and nutrients until the time is right. This system is said to be able to feed your plants for up to 6 whole months!

In addition to this, the fibre smart technology refers to small pieces of hollow wood that is there to promote air circulation in the soil and to create the right balance of air and water in order for the plants to grow to their full potential. Then there is their waterlock technology, that allows Miracle-Gro’s compost to retain 25% more water than standard composts. All this, plus an excellent selection 14 different, vital minerals, adds up to an excellent product that is aiming to be one step ahead of the competition. 

Miracle-Gro are selling this product in bag sizes of 20, 40, or 50 litres, and again it is a little more expensive than some other, less known brands, but I wouldn’t say it is overpriced and you do get a quality product for your money.

Miracle-Gro All Purpose Compost

Another fully natural compost option that is pleasing gardeners by the bucketload is this product from Baltic Worm. This worm casting based compost can be used on just about anything, and also anywhere. You can use it on your veggies, flower beds, in your hanging baskets, repot your houseplants with it, and use it as a soil enhancer.

This compost goes through an interesting process while being made. First cow manure is collected and then turned into natural compost, before compost worms are used to turn it into vermicompost. The resulting product is a product that your plants and crops will love.
This stuff really works. Producing results that many other all-purpose composts just can’t match, and keeping your garden looking as healthy as can be.

What’s more, this product has a very long shelf life and can be stored for literally years while still remaining usable. You can use Baltic Worm vermicompost for your houseplants, just as you can with your flower beds. It has a pleasant smell that is not too strong and this makes it ideal for indoors.

This is extremely versatile and can be used in all manner of ways. You want to mix it with your soil? Go ahead. Prefer to sprinkle some on top and water it? Be my guest. Use it as a potting mix? Of course you can!  This really is an excellent product and one you should really give a try. I’m sure you’ll be happy with the results, as so many other gardeners are.

Best Soil Compost Buyer’s Guide

There is no shortage of compost products available these days. Just a quick search on Amazon brings up more results than you can shake a stick at, and it can be a struggle trying to figure out which one you should buy. In the hopes of making things a little easier for you, we have put together this little buyer’s guide to highlight a couple of things you might want to keep in mind.

Multi-purpose or specific compost?

There are composts that can be used on a wide range of different plants, and these usually can be used both outdoors and in the home. Called multi-purpose or all-purpose composts, they are a good bet for people who are new to gardening and aren’t quite sure which type to use. They are also good for large gardens as you can buy in bulk and save money, and just use it on everything.

Some composts are designed for specific purposes. For example, there are potting composts that work better with plants grown in containers or pot, then there are composts made specifically for houseplants. If you have succulents, you might want to use a compost that has been made to get the most out of those types of plants rather than an all-purpose one.

Organic composts

Lots of people prefer organic composts as they are better for the environment, and some will say that they get better results from them, but the jury is still out on that. If you are growing things that you will eventually eat like fruits and vegetables, then an organic compost is definitely the way to go, as you don’t want any kinds of chemicals in your body if you can help it.


Peat has been used in composts for a very long time, but recently scientists and gardeners have started warning people not to use it as it is very bad for the environment. Peat mining releases a lot of carbon into the atmosphere and also has a negative effect on many types of wildlife. So, If you want to do your part and help save the planet and its inhabitants, choose a reduced peat or peat-free product.

How much compost do you need?

The size of the bags or boxes of compost range from just a few litres to up to 100 litres or more. If you only have a couple of containers to repot, there’s really no point buying a huge bag, as you will then just have to find a place to store it, and it will lose its effectiveness after a while anyway, leaving it pretty much useless.

Some organic composts like the vermicompost from Baltic Worm we reviewed above, have a very long storage life, so this would be the exception to that, but for most products it’s better just buy what you need for now. You can always order more later.

About Terry Smith

I’m Terry Smith from gardentoolbox.co.uk, a professional landscape designer, hobbyist gardener, and barbecue fanatic with 20 years experience building and restoring. So as you go through my site you'll watch me document some of the professional garden installs I make as well as the major projects I take on at home. While sharing those experiences and guiding you, I'll be recommending some great tools I use to enable this along the way so you can really buy in confidence. Always feel free to pop me a message: info@gardentoolbox.co.uk

View all posts by Terry Smith

Leave a Reply

Your email address will not be published. Required fields are marked *