The Grodan Group supply a continuous water content meter (WCM) which registers the amount of water, EC and temperature in rockwool substrates. Water dosage can be precisely controlled, but how much water is being taken up by the plant and how much water remains in the rockwool slab at any given moment? Using the Meter, it is possible to monitor the changes. It is noticeable how little water Gerbera plants use in the autumn.  Without continuous monitoring, it would be too risky to cultivate the plants with so little water as autumn approaches. The Meter also demonstrates that crops use very little water in the early morning that calls for a delayed morning irrigation, certainly in winter. In contrast, in an actively growing crop, irrigation can be continued for longer period towards sunset. Another advantage is that it is possible to avoid the problem of broken stems. This problem arises with sensitive varieties during periods when the moisture tension is high. Buds and flower tops can break off the stems when handled during harvesting. This happens more readily when the rockwool slab is saturated. Many Gerbera growers have become accustomed to harvesting later in the morning to avoid this.  By referring to Meter's graphics, it is possible to establish a safe moment to harvest. The Meter's pins are located in a slab where the water content is a reasonable greenhouse average. By following the course and the extent of the variation in water content, it is possible to achieve a more stable irrigation pattern which in turn permits a healthier crop with more uniform flower size, better quality and higher productivity.  The Meter can also be used for pots with Growcube in addition to rockwool slabs. In this instance, the sensor's pins are not set vertically in the slab but are pushed horizontally through the side of the pot. Harmen Kamminga "Vakblad voor de Bloemisterij". Grodan Med. S/A Fax 0034 950 489703 E-mail: info@grodan.com www.grodan.com