Selective harvesting is becoming more popular as a cost cutting measure. This means that the same room is picked over several times a day. This system is only successful if the mushrooms are spread properly and do not occur in heavy flushes. Many cultivation techniques can be used to steer towards this result but don’t underestimate the influence of casing soil. The grower is aiming to produce a flush of around 15 m² so the flush is easy to pick. By limiting the size of the flush the piece weight also stays acceptable. To limit the actual number of fruits the casing soil must be heavy enough and not too crumbly inn texture. Use casing soil that is more heavily structured from the start and avoid over processing the soil. The right spread in the flush to lengthen the number of harvesting days is achieved by filling the casing soil unevenly. This means keeping the casing soil surface open so successive generations of mushrooms are encouraged during blow down. This shows that without resorting to major changes in cultivation techniques just choosing a certain type of casing soil will determine if the flush is suitable for selective picking or not.
Henk van Gerwen, AdVisie 'The mushroom cultivation advisors’