Chestnut mushroom growing has received more attention recently and one of the problems often facing aspirant growers is excessive pinheading in the first flush. Most chestnut mushroom varieties fruit easily - and this feature should be taken into account.
Start with a heavy but open-structured casing soil. Casing soil that is too fine will automatically lead to over fruiting. This type of casing soil will have to be sprayed in a diminishing pattern. In other words give most water at the start of the cultivation cycle and reduce the amount as the time for pinheading approaches. Too much water on the last day before blow down will always have a negative effect Cac-ing ensures a better spread making pinheading and development easier to control If possible avoid ruffling and leave the casing soil surface open. Blow down with an RH of 92 to 93% during the first four days and leave the CO2 content high for as long as possible. The mycelium will continue to develop for a while, but do not use spraying to restrict growth. This will just cause too much uniformity and too many pinheads.
Henk van Gerwen, AdVisie ‘The mushroom cultivation advisors’