Medium and Substrates

Rockwool

Rockwool is a light-weight and cheap mineral which does an excellent job of retaining water. It is made up of basalt and a silica compound and is available in a variety of cube sizes, blocks, slabs or shredded up, also known as ‘floc’.

Rockwool is naturally alkaline, therefore you will need to neutralise it in a solution of pH 4-5 before using it as a substrate for plants. The neutralisation process can take up to 24 hours. Because rockwool doesn’t require watering as much, it’s important to keep tabs on how much water your plant is actually getting. Too much water, and there is risk of fungus and lack of oxygen affecting the roots.

Perlite

Perlite is a special type of igneous amorphic stone used in agriculture, horticulture and botany as a soil amendment. It can also be used as a standalone medium for hydroponics and cuttings in early stages of growth. Perlite is light-weight and looks like crumbly white pebbles. It is highly permeable, however doesn’t retain a lot of water, meaning it will help prevent compaction and allow nutrients and water to circulate easily. Many growers add it as a mix and additive to other substrates. However, be careful when working with perlite. The tiny dust particles can be dangerous to your lungs if inhaled.

Cocos | Coir and Fibre

These days good quality coco has proven to be a superior growth substrate for a large number of different crops, both for small and commercial scale. Coco or coir is the outside layer of coconut husks (or mesocarp) which is first soaked in water. It is then processed in a term called ‘retting’. The coir pith then undergoes further processing and decomposition, making it more suitable as a plant growth medium.

Cocos is developed from a renewable and environmentally sound resource and is available in a range of different products from 50L pre-packaged bags; cocos and perlite blends; and small to large compressed ‘cubes’ (soaked and expanded ready to use).

Seeds

Depending on what you’re planning to grow, buying seeds is the most common way to get started.

It is important to ensure you start with healthy seeds. You can tell the difference because a healthy seed is usually hard and smooth, while a sterile or unripe seed is pale and mat in colour and texture.

You can germinate seeds in different ways, however the most economical and assured way is indoors where the environment is controlled and the seedling is protected. For a seed to germinate, it needs to absorb water, signalling the beginning of the biological processes inside the seed – bringing it to life so to speak as a seedling. After you have exposed your seed to water, the end of the root appears and the seed should be removed from the water and placed on damp kitchen paper. How long it takes for the root to appear varies greatly depending on the variety and the age of the seed and you should always ensure that the seeds have enough space for ventilation which will prevent mould from forming.

A simple method of germinating seeds, is to place the seed on a piece of paper towel that is damp. Cover the seed and store in a dark place. Make sure the paper towel remains damp, but ensure the seed does not drown in a puddle of water (remember that seeds need oxygen to germinate). Once the seed “pops”, the tap root sprouts and the new top shoot shows, transfer your seedling to your chosen medium in a small container or plant directly into a grow bucket.