Plant water evaporates considerably less in winter than in summer, which reduces the need for water. During this time, without adjustment of the soil substrate, there can be an increased risk of root problems.
The choice for a more airy substrate in winter is crucial, especially with short-term cultures during which growing power is important, according to RHP, a leading European knowledge center for potting soil and substrates.
Many factors in the root environment influence the functioning and growth of roots. The availability of oxygen and water, the temperature, the penetration resistance, pH, and EC all play a role. Less evaporation of water increases the risk of a lack of oxygen in a substrate. When this happens, root problems in the culture can increase.
Another reason to choose a more airy substrate in winter, according to RHP, is the difference in uptake of nutrients in summer and in winter. This differs not just per crop, but also per season. Crops usually take up more nutrients and less water in winter than in summer. To realize an optimal root environment for a certain culture, substrate type, watering, and composition of the nutrient solution each have to be adjusted to each other.
Substrates certified through RHP are designed to provide an optimal start of the culture. The RHP quality mark means that the substrate meets the right quality requirements for water and air content, pH, and EC. It also means that the substrate is pure and clean, and that it can be used without risks for the culture.