The new EU regulation concerning organic production, emphasizes maintaining and increasing biological activity in the soil. Specifically for greenhouses, the use of green manures (for a short period) and higher plant diversity are imposed. However, very little is currently known about the use of green manures in organic heated greenhouses. There are also many questions about the practical possibility of including green manures in a rotation with fruiting vegetables. Exploration of species that can be used as green manure, when they are best sown and what impact can be expected on the main crop is therefore in order. The aim of this project is to give growers insight into the possibilities and bottlenecks of green manures in greenhouses.

This project included 4 tests. In the first test we wanted to know which green manures grow well after fruity vegetables cultivation. Since such crops are not cleared until the end of October, it seems difficult to sow a green manure after cultivation. Green rye can be sown late. In the 2nd test we sowed green manures under tomatoes at different times. This showed that seeding during a crop is not so easy due to limited light availability under a tomato crop. In a 3rd test we sowed green manures before planting 4 fruity vegetable crops (pepper, eggplant, tomato, cucumber). The green manures were marigolds (Tagetes patula “Ground control”, floss flower (Ageratum houstonianum), oregano (Origanum vulgare), summer vetch (Vicia sativa) and facelia (Phacelia tanacetifolia). The best growth took place under peppers, and the least under eggplants. The most suitable green manure from the trial was Tagetes patula “Ground control”. In the similar (4th) trial at Bio Verbeek, Tagetes (sparky mix) was the preferred green manure.