There is no fixed rule for determining the best substrate for seedbeds. We review the types and help you choose the most suitable one.
In reality, there is no fixed rule for determining the best substrate for seedbeds. Most of the substrates offered on the market, such as organic substrates for seedbeds, are composed of peat as their main element, to which other materials are usually added, such as perlite, coco coir, sand or vermiculite, to modify the properties of water retention, aeration and drainage.
Types of substrate used in seedbeds
To create the best substrate for seedbeds you need to address the specific germination needs of the seeds. In general, particular conditions of temperature, humidity and oxygenation are required. The ideal way to achieve them is to combine several substrates, in different proportions, so that each one contributes its different properties to our final substrate. The most commonly used substrates for this purpose are blond and black peat, coco coir and universal substrate.
Black peat
When we think about using black peat to create a good substrate for seedbeds, we have to bear in mind that this substrate is made of highly decomposed organic matter that offers a great water retention capacity, but not much aeration. On the other hand, it contains few nitrogen nutrients, although it provides humic substances and precursors of the microorganisms beneficial to the root.
Blond peat
Blond peat comes from the upper layers of peat bogs, such as the different types of moss of the Sphagnum genus. That is why it is a substrate very rich in organic matter. It has a coarse, granular texture that provides high levels of aeration, which also favours root formation, and acidifies the substrate, which can be beneficial if our substrate is too alkaline.
Coco coir
Coco coir is a 100% organic, environmentally friendly material. It is a substrate with a high degree of porosity that favours root development. It has a high lignin content, which boosts the proliferation of microorganisms beneficial to plant roots and is ideal for solving compaction problems in the substrate.
Universal substrate
Universal substrate is defined as a substrate suitable for the vast majority of crops, as each manufacturer creates its own blend using different substrates such as peats, vermiculite, perlite and coco coir, among others. Since, in general, each of them tends to respond quite well to a wide range of plants and purposes, it is quite well known and widely used.
Which substrate to choose for seedbeds?
To create our special substrate for seedbeds we must picture the end result and visualise a practically inert, lightly fertilised substrate, very well aerated and with a high water retention capacity. With this in mind, we will choose peat as the base of our substrate. Peats with fine, lightly decomposed fibres are preferable so that aeration is compatible with moisture. To achieve this, we mix blond and black peat 50/50. From the black we obtain the fine particles and water retention, while from the blond we get the less decomposed matter and improved aeration. Finally, we add coco coir to increase oxygenation while stabilising the pH of the mix. With this simple recipe we will achieve spectacular results.
