Circular water provision for horticulture: Water in the greenhouse

Water supply is of crucial importance for greenhouse horticulture. An adequate supply of fresh (irrigation) water has to be available – during dry periods as well – and the water needs to be clean and not contain too many salts. Commitments have moreover been made to significantly decrease discharges of plant protection products from greenhouse horticulture in the years ahead and, ultimately, to eliminate them altogether.

This project is part of a coherent programme which should result in an integrated and sustainable (irrigation) water provision: the securing of ‘good irrigation water’, reduction of the use of disinfectants, and zero emissions of nutrients and environmentally-alien substances. The cluster research programme, ‘Circular Water Provision for (Greenhouse) Horticulture’, consists of four projects:

  1. Water to the greenhouse: freshwater provision and well technology
  2. Water in the greenhouse: microbially ‘healthy’ irrigation water
  3. Water from the greenhouse: water treatment and reuse
  4. Operate: operating circular irrigation water systems

Within these four projects, the supply, discharge and use of water on a scale beyond that of the individual horticulturalists are studied. In this way, a sharper focus can be placed on closing the water cycle, increasing the sector’s self-sufficiency, assuring efficient water use, matching (regional) water surpluses and shortages in time and place, and reusing water.


The ‘Water in the greenhouse’ project is aimed at the development of microbially ‘healthy’ irrigation water. A lot of (greenhouse) horticultural involves cultivation on water (substrate cultivation). This can lead to the development in the greenhouse of biofilms, plant disease(s), stunted growth, product loss, etc.


There are indications that problems exist, but there is little clarity about their extent, which microorganisms cause them, and what can be done about them. Currently, the response in many cases is to make use of permanent disinfection (e.g., hydrogen peroxide, ozone), but these control methods often produce no results; this could be because they kill off protective microorganisms.


The research aims to develop methods to prevent of contain the growth of plant pathogenetic microorganisms in the water. This could limit the use of disinfection (cost savings). Moreover, the water would have to be refreshed with clean water less frequently, which would reduce discharges into the environment. The project’s practical implementation is currently underway (LTO Glaskracht).