How to Use Growing Mats?
Because a growing mat as an inert medium is excellent for use in a window box as well as for drip irrigation within a hydroponic system, let us now briefly focus on the TOP growing mats on the market and their practical use.

These growing mats for plant cultivation are made from coconut fibres (besides Cocos Slab, for example also UGro Slab - compressed mat). Compared with the mineral-based mats listed below, they stand out above all for their 100% natural composition and meet the strictest quality standards (RHP).
When using the one-metre growing mat Cocos Slab from Plagron, proceed as follows:
- Shake well before use, but do not rinse. The substrate is ready for immediate use.
- Just check that the drainage holes at the bottom of the Cocos slab are large enough.
- Place the plants into the Cocos slab.
- pH of the water to 5.5.
- The advantage of this growing mat from the Plagron brand is the fact that it naturally ensures low EC values.
- The manufacturer’s dosing tables will help you with the nutrition of plants grown in growing mats. Dosing tables are provided directly by the manufacturer. The Cocos Slab growing mats are a truly perfect medium for hydroponics. If you decide to use them, we recommend combining them with two-part nutrition from the same brand, namely Plagron Cocos A+B, as well as with the supplements Power Roots, Pure Enzymes and Green Sensation.
- The substrate itself contains no fertilisers, so you can dose the nutrition above according to the dosing tables from the very first day. However, the substrate contains the beneficial fungus Trichoderma, which has a beneficial effect on the healthy development of a strong root system in your plants, as it can surround it and effectively protect it, for example against mould attack.
- You can also use these growing mats from Plagron repeatedly. This, together with their purely organic origin and composition, is their main advantage compared with Grodan growing mats (see below). You can tell when it is time to replace the growing medium after several months by the measured value of EC, if it is higher than 1.8, or pH, if it is lower than 5.4 or higher than 6.5. You will find everything for measuring pH and EC values HERE.
Classic, Master and Expert (Grodan)

- Grodan growing mats have a mineral origin. They are made of horizontal fibres from high-quality basalt wool (rockwool), which slightly raises pH.
- As an example, we can mention the best-selling Grodan Master growing mats with different densities of hydrophilic fibres. Compared with the Classic or Expert mats, we found better water management and fertilisers with the MASTER mat.
- These growing mats have a balanced ratio of water and air. They are firm yet airy, increase the plants’ oxygen absorption and uptake of fertilisers, and maintain stable pH. They also ensure uniform plant development in the slab. In addition, they allow full control over the electrical conductivity values of the solution. As a result, among growers they are considered one of the most popular growing media for hydroponics.
- We recommend using one growing mat for only one growing cycle!
- You can use them on their own, but also as a practical base for rockwool propagation cubes.
- Before use, rockwool needs to be soaked in lukewarm water at approx. 25 °C, preferably already with adjusted pH in the range of 5.8–6.
COGR - compressed mat (Canna)

A separate chapter in the case of growing mats is Canna COGR - compressed mat, made from a special blend of coconut husks, fibres and coconut granulate, which will satisfy even the most demanding hydroponics enthusiasts.
- This inert substrate from a prestigious manufacturer is simply a clear guarantee of maximum aeration as well as absorption of nutrients and moisture!
- Just like Plagron mats, you can also use Canna COGR repeatedly - even up to three times in a row, and moreover without the slightest loss of quality.
- It is important first to moisten the compressed slabs with the special COGR Buffering Agent. Then it is necessary to fertilise with COGR Vega during the vegetative phase and switch to COGR Flores during the flowering period.
- In terms of practical use, part of these growing mats can be crushed and divided into any flowerpots. You therefore do not have to limit your purchase only to window boxes and hydroponic systems.
If you are involved in hydroponics and have not yet tried growing mats, perhaps now is the time to put that right. And if you have any questions, we will be happy to answer them at the well-known address info@higarden.eu.
We also recommend these products:
- Plagron Cocos A+B (from 329 CZK): two-part plant nutrition ideal for cultivating plants in Cocos Slab growing mats.
- Libra hydroponic window box (199 CZK): designed for both coconut and rockwool growing mats.
- pH and EC metres (from 99 CZK)
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