WESTLAND, The Netherlands: Plants evaporate considerably less in winter than in summer, therefore the need for water is lower. Without adjustment of the substrate, there will be an increased risk of root problems. The choice for a more airy substrate in winter is therefore crucial, especially with short term cultures during which growing-power is important, the Dutch knowledge centre for substrates RHP advises.
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 for example EC play a role. Less evaporation of water increases the risk of a lack of oxygen in a substrate. And in this way root problems in the culture increase. To avoid these problems, the knowledge centre for substrates RHP advises to use a more airy substrate in winter than in summer.
Another reason to choose for a more airy substrate in winter, is the difference in uptake of nutrients in summer and in winter. This already differs per crop, but also per season. Crops usually take up more nutrients and less water in winter than in summer. To realise an optimal root environment for a certain culture, substrate type, watering and composition of the nutrient solution have to be adjusted to each other.
RHP certified substrates guarantee an optimal start of the culture. The RHP quality mark guarantees that the substrate meets the right quality requirements for water and air content, pH and for example EC. It also guarantees that the substrate is pure and clean and that it can be used without risks for the culture. The RHP quality mark guarantees the quality of growing media in the chain, from raw materials production until processing and delivery at the company of the user. Since1963 RHP has been the European knowledge centre for substrates (growing media).