Light levels are now increasing rapidly as are the outside temperatures. The ventilators will be opened, subject to restriction with adequate P-band settings and outside weather influences to prevent cold air entering the glasshouse. Consequently, water uptake by the crop will increase but the weather can also fluctuate massively at this time of year, especially in Europe and Canada. However, maintaining a stable substrate EC is not difficult so long as correct settings are implemented. Again the standard graphic that depicts WC, EC & radiation is a useful tool to use.
In order to maintain the correct generative/vegetative balance in the crop as the first harvests are taken and the fruit load is stabilized it is important to maintain a stable root zone environment. Not least a stable substrate EC. As such irrigation must now be matched to the light levels and enough drain has to be achieved over 24 hrs, especially on bright days to level EC and balance the substrate nutrition.
At this time of year, almost all growers tend to become nervous of the substrate EC. In some circumstances, a first reaction may be to decrease the dripping EC as soon as the days become brighter while keeping the stop time fixed so as not to give too much water on the darker days.