What’s the Best Growing Medium: Soil, Coco or Pebbles?

Substrates and Grow Medium Explained

The substrate, often referred to as grow media, provides your roots with the perfect environment to establish and thrive. It is arguably the most important component to take into consideration when caring for your plants. You can find a variety of different grow medium on the market such as coco, clay pebbles, and soil. You’ll often find grow media that is comprised multiple different substrates in order to create a mix that provides excellent aeration and water retention, ultimately helping your plants thrive. If you’re new to this, this may seem a little bit confusing so we’ve compiled some information below to help you get a better understanding.

It Is important that the substrate you use provides anchorage for your crops, aeration for your roots, and the ability to retain water. Manufacturers will ensure that your grow medium is free from pathogens, and is chemically and physically stable from the date of manufacture, up until you put it to use.
Growers tend to pick the substrates that tend to give the highest harvest yields, however at London Grow we feel it’s important that you have a good understanding of the substrates available so you can pick the best grow medium for your needs.

What is Soil?

Soil is by far the most familiar, and common grow medium for both beginner and professional growers across the globe. When selecting a soil or soil mix, it is important to take into consideration factors such as pH, fertilizer content, aeration, texture and infestation levels. Due to affordability, and accessibility, it is often the go-to substrate for growers.

There are three major functions to soil. It provides a basis for plant growth, a habitat for bacteria and fungi, and it filters water and recycles raw materials. It helps healthy plant development by providing ideal conditions for your plants’ roots to extend downwards and/or outwards through the soil to anchor the plant. Air gets trapped in the spaces between the soil particles which provides additional oxygen that can be absorbed by the plant root cells, helping break down sugars to convert into energy to the plants.

Water aids the transportation of nutrients, sustains the photosynthetic process, and helps to maintain cell size. With this in mind it is important to choose a high-quality soil with a light structure that increases overall water retention. Products such as CANNA Terra Professional Plus contains white and black peat, perlite, and organic worm humus. The result of this is a soil with a light structure that aids increased water absorption capabilities whilst optimising the conditions for bio active life to thrive.

We have found it to be the best soil to grow strong and healthy plants. It also encourages the development of beneficial bacteria and microbes to support healthy crops. Growers also typically use Biobizz All Mix Potting Soil, which is a certified organic soil made for potting large plants and delivers exceptional development rates. The soil encourages the growth of beneficial microbes in the root-zone and comprises a perfect balance of nutrients for excellent harvests. Biobizz and CANNA provide the best soil to grow larger and healthier plants, which deliver well-formed flowers and fruits.


Biobizz Light Mix Soil


CANNA Terra Professional


Ecothrive Eco Life Soil



What is Coco Coir?

Coco Coir is a relatively new substrate when compared with soil. It is often found as a stand-alone product, or combined with soil, vermiculite, or clay pebbles. It is made by de-fibering coconut husks and processing it into coco peat by removing the bristle fibres. Unlike soil, coco coir is completely inert meaning you will need to provide your plants with all of the nutrients it needs to optimise healthy growth. This is great for those looking to have total control over your plants diet, but it is important to avoid overfeeding. This substrate generally has a neutral pH ranging between 5.2 and 6.8. When compared with soil, coco tends to dry out a lot quicker, meaning your plants will need to be watered more frequently.

Key benefits of opting for growing in coco include high yields and quick harvest, additional room for root development and pH neutral values. As well as this, it helps reduce the risk of pests and their sustainability, whilst also minimising pathogen content. We’ve found coco coir a popular choice for those of you using run-to-waste systems. With the right nutrients in your tank, the coco will enable your plants to easily uptake nutrients resulting in healthy development.
We at London Grow recommend opting for a top-quality Coco product like CANNA Coco Professional Plus or Substra Coco Bricks to help you achieve strong crops and an abundant harvest. Substra Coco Bricks when expanded creates an airy and moist environment that’ll help with explosive root development. It is bio-degradable, easy to use, free from pathogens and pests and is highly affordable.


Substra Coco Brick


CANNA Coco Pro Plus


Gold Label Coco Mix



What are Clay Pebbles?

Clay pebbles are commonly used in recirculating hydroponic systems as a substrate layer. It is made by firing pieces of clay in a kiln, causing them to expand whilst being sterilised in the process. It is ideal for use as a base layer, mixed with other grow mediums because it offers excellent drainage. The key benefit of using clay pebbles is their ability to retain moisture. As well as this, they are lightweight, and porous, helping maximise aeration amongst the root zone.

The moisture retaining property of clay pebbles makes it ideal for ensuring your plants stay hydrated. It easily absorbs water and stores it for your plants to uptake nutrients as needed. Clay pebbles are completely natural and environmentally friendly. They have a long-life and can be used multiple times without the quality deteriorating. At London Grow we’ve found CANNA Aqua Clay Pebbles to be the best choice for your plants. They have high porosity, increased air content and low salt content. These clay pebbles have a porous texture and can hold increased amounts of water.


CANNA Aqua Clay Pebbles


H&G Clay Pebbles




Beginner and Professional growers across the globe use a variety of growing mediums including soil, coco, and clay pebbles. In the above we’ve learnt key benefits to each substrate, and how they can be used. This in turn will help you to decide which is the best growing medium for your crops, by taking into consideration your plants needs and the area where you’re growing your crops.




Grow media