It sometimes happens that we want to reuse containers filled with growing medium from the previous season by planting new plants in them. However, this specific type of recycling has several drawbacks and can lead to unpredictable consequences for plants. Most new plants grown in last year’s soil will react poorly to the increased salt content in such a substrate.
They also accumulate fertilizers, which are partly composed of insoluble compounds (mainly salts). If these compounds reach a critical concentration for the roots, the plants will no longer be able to absorb water. As a result, their basic physiological functions become severely disrupted, affecting growth vigor and flower quality.
In addition, old growing media often harbor overwintering pests and spores of pathogenic fungi. For this reason, it is recommended to replace the soil with fresh substrate every year and thoroughly clean the containers. The best way to do this is with water mixed with garlic-infused potassium soap.
When choosing a substrate for container plants, it is important to consider water retention capacity, structure, and the presence of air-filled pores. The latter is best achieved by adding Ecofibrex wood fibres to high-quality peat (the main component of potting mixes).
