How and why to revitalise substrate?

With the harvest season comes a number of questions about what to do with spent substrate after harvesting. The topic of today’s article is therefore the revitalisation, or regeneration, of growing substrates.

• Of course, you can throw spent substrate into the bin, but there are more environmentally friendly solutions that will also save you money, as you will not have to keep buying brand-new medium for growing containers. On the contrary, quality growing substrates, which we recommend a little further below, can then be used repeatedly.
• The revitalisation process itself depends on whether you use soil or coco as the growing medium.

SOIL

• In a pot, the plant ideally forms a rich and branched root system, which gradually fills the relevant growing container.
• At the same time, it absorbs nutrients that were supplied to the soil through watering made up of water and fertilisers.
• The chemical composition and properties of the soil are therefore significantly different after harvesting compared with the original state or the state during the growing cycle.
• Spent soil no longer contains a sufficient amount of nutrients and, if mineral-based fertilisers were applied to it, it also contains excess salts and other residual substances, which are highly undesirable for any further use.
• Soil mix naturally loses its ability to retain water after harvesting. It is, or at least should be in the case of successful previous cultivation, practically completely penetrated by the root ball.
• If we planted a new small plant into such spent soil without first revitalising it, the result in the vast majority of cases would be only infection by pathogens from decaying roots and subsequent death.
• Soil in the wild is revitalised naturally without human intervention. However, if we are cultivating plants in growing containers, you must carry out the revitalisation of spent substrate yourself. Here is the procedure:

1. Remove all above-ground parts of the plants and any other plant material.
2. Rinse the soil with water (ideally water from reverse osmosis, see the separate article) to wash away fertiliser residues and other undesirable substances, with 2 to 3 litres of water per 10 litres of soil being considered an ideal volume. We recommend repeating this process at least three times so that all substances we want to remove from the substrate are truly washed out.
3. Sterilise the substrate, especially if the plants were affected by pests or diseases during the previous growing cycle. The simplest method of substrate sterilisation is to rinse it with boiling water. It is advisable to support the sterilisation of the substrate with hand hygiene; alternatively, you can use disposable latex or clean garden gloves.
4. The result of these steps is clean soil without nutrients. Before it is used again, these need to be replenished by mixing in a strongly pre-fertilised substrate, or quality compost. Here it is necessary to emphasise the rule that old, revitalised substrate is mixed with a new soil mix or compost only after we spread it out in a dry and sufficiently airy place, where we use a sieve to remove all remnants of the root ball from the previous growing cycle.

COCO

• The process of revitalising spent coco substrates largely corresponds to the above steps relating to soil revitalisation.
• Plant and root residues must again be removed.
• Small roots that we are unable to remove manually are helped to break down by enzymatic products, which you can add to the watering during the first weeks of the upcoming growing cycle.
• Sterilisation is carried out with boiling water or a solution of hydrogen peroxide.
• If you use a peroxide solution, do not forget that it is a chemical that must be washed away with a further rinse!
• While revitalised soil is left to dry completely before being mixed with compost or a soil mix with nutrients, revitalised coco substrates can be mixed with fresh coco while still wet.
• By mixing revitalised coco substrate with soil sufficiently rich in nutrients, we obtain a mixture suitable for planting.

If you have any questions related to the possibilities offered to growers by the substrate revitalisation method, do not hesitate to contact us at the well-known address info@higarden.cz.

We also recommend these products: 

• Canna Terra Professional Plus 50 l (from 479 CZK)
• Canna Coco Professional Plus 50 l (from 389 CZK)
• Canna Cannazym Previous article