As below, so above: as are the roots, so will be the aerial part of the plant. The utmost importance of taking care of the substrate used has already been seen in the article Healthy roots, happy plants: how to choose the best substrate for pots, but it is such a complex and varied world that it is necessary to dig a little deeper into it. If plant growth stops after transplanting, a change in substrate may be to blame.
Obviously, after such a delicate operation as repotting the plant, there may be a slight delay in development. But, if the substrate chosen is of good quality and conforms to the ideal parameters that we analyze in growing potted plants (that is, pot, substrate and space), this should not be a problem for the plant, which Will quickly get used to his new environment. Aeration is the main key for the roots to be comfortable.
Today, one of the most widely used organic substrates that respects the environment is compost obtained from plant residues and prunings, which in most cases obtains a good quality compost with excellent aeration. Many business houses have signed up for this material’s sustainability, easy to obtain and often discontinued. In this way, the environmental inconveniences caused by the extraction of peat, for example, or the import of materials such as coconut fiber from distant countries such as Sri Lanka or the Ivory Coast, are eliminated. But this final substrate, coconut fiber, is another one most commonly used to shelter plant roots.
A simple walk through a nursery or a florist will clue that this is the organic substrate most plant growers choose for cultivation for its remarkable properties. It can be recognized with the naked eye when you see some brown and very hard hairs coming out of the surface of the vessel, which correspond to the fibers that protect the giant seed, the 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 require in high amounts and with which they maintain strong growth and greater resistance to cold and diseases.
Another benefit is that coconut fiber inhibits the growth of pathogens, such as some fungi that affect plants at the root level. In any case, it is quite common to find universal substrate mixes that contain both compost and coconut fiber and each contributes with its own properties to the success of the crop. Similarly, pine bark, which is a waste of the wood industry, can also participate in these substrates. It is a component that provides high root aeration necessary for the plant.
With regard to inorganic substrates of mineral origin, there are many that are to a greater or lesser extent part of packed substrates. Sand – both river and silica – and perlite or vermiculite remain queens because of their ubiquity and usefulness. Perlite is a substance made from crushed siliceous volcanic rocks, which are heated to 1,000 °C so they explode and expand like 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 grains with their fingers. Its high internal porosity and rough surface make perlite an optimal ingredient for water retention and an ideal reservoir from which the fine roots of plants come to drink. Paradoxically, it also sponges up the soil and loosens it, allowing more air to move underground. With all these advantages, it is not surprising that it is present in so many substrates.
Likewise, sand is not difficult to find among universal substrates that are optimal for the vast majority of plants, both grown indoors and outdoors. This is because, like the other substrates appearing in this review, they are primarily used to add needed aeration to the roots. Instead, vermiculite, despite its good qualities, is less commonly present in substrate mixes because it is more expensive than the other components. It is a particleboard that has a convergence of positive aspects such as good air circulation as well as water and nutrient retention. Something extraordinary about vermiculite is that it provides potassium and magnesium to the plant, which makes it a nutrient good for vegetables. As can be seen, each substrate has benefits for plants and it is important to know them all well in order to secure their happiness and good growth.