March 4, 2024


As it is below, so it is above: as the roots are, so will the aerial part of the plant. It was already seen in the article Healthy roots, happy plants: how to choose the best substrate for pots the extreme importance of taking care of the substrate that is used, but it is such a complex and varied world that it is necessary to dig a little more into it. If a plant’s growth stops after transplanting, the change in substrate may be to blame.

Obviously, after such a delicate operation as changing a plant to a new pot, a slight delay in growth can occur. But, if the chosen substrate is of quality and adjusts to the ideal parameters that we analyze in Grow plants in a pot (those are, pot, substrate and place), it should not be a problem for the plant, which will quickly get used to its new environment. Aeration is the main key for the roots to be comfortable.

Today, one of the most widely used organic substrates that is respectful of the environment is the one derived from composting plant remains and pruning, obtaining a good quality compost with excellent aeration in most cases. Many commercial houses have signed up for the sustainability of this material, easy to acquire and often close. In this way, the environmental inconveniences generated by the extraction of peat, for example, or the importation of materials such as coconut fiber, from distant countries such as Sri Lanka or the Ivory Coast, are eliminated. But this last substrate, coconut fiber, is another of the most used to shelter the roots of plants.

At the time of transplantation, it must be taken into account to provide the most suitable substrate for the plant.
At the time of transplantation, it must be taken into account to provide the most suitable substrate for the plant.Tara Moore (Getty Images)

A simple walk through a nursery or a florist will give the clue that this is the organic substrate that most plant growers choose for its remarkable qualities for cultivation. It can be identified with the naked eye when you see some brownish and very rigid hairs protruding from the surface of the pot, which correspond to the fibers that protect the huge seed that is a coconut. It is a stable material over time, with an excellent water retention capacity and, at the same time, with a high aeration capacity. Likewise, coconut fiber provides potassium, one of the elements that plants need in greater quantity and with which they maintain strong growth and greater resistance to cold and diseases.

Another of its benefits is that coconut fiber inhibits the growth of pathogens, such as certain fungi that affect plants at the root level. In any case, it is quite common to find in universal substrate mixtures that both compost and coconut fiber are mixed and that each one contributes with its qualities to the success of the crop. Likewise, pine bark, a waste from the timber industry, can also participate in these substrates. It is a component that provides high root aeration, essential for the plant.

The coconut fiber with its characteristic stiff hairs.
The coconut fiber with its characteristic stiff hairs.Catherine McQueen (Getty Images)

Regarding the inorganic substrates, of mineral origin, there are several that are part, to a greater or lesser extent, of the packaged substrates. The sands —both river and silica— and perlite or vermiculite continue to be the queens, due to their ubiquity and usefulness. Perlite is a material from crushed siliceous volcanic rocks, heated to 1,000 degrees Celsius, so they burst and expand as if it were popcorn. With its white appearance, it often attracts the attention of novice growers, who are surprised by its floury texture when they crush one of its particles with their fingertips. Its high internal porosity and rough surface make perlite an optimal component for water retention and it becomes a perfect reservoir from which the fine roots of the plant come to drink. Paradoxically, it also sponges the soil and loosens it, allowing a greater amount of air underground. With all these advantages, it is not surprising that it is present in so many substrates.

Perlite is one of the most common components of universal substrates.
Perlite is one of the most common components of universal substrates.Turnervisual (Getty Images)

Similarly, it is difficult not to find sand in universal substrates, which are optimal for the vast majority of plants, grown both indoors and outdoors. This is because, like other substrates that appear in this review, they add the necessary aeration for the roots, mainly. Instead, vermiculite, despite its good qualities, is less present in substrate mixes because it is more expensive than other components. It is a particle in which such positive aspects converge as incorporating great aeration, as well as water and nutrient retention. Something exceptional that vermiculite has is that it provides potassium and magnesium to the plant, which makes it a nutritional ally for vegetables. As can be seen, each substrate has benefits for plants and it is important to know them all well to safeguard their happiness and good growth.

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