This section is from the book "Commercial Gardening Vol4", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
A damp-over should be given before picking; the Mushrooms are easier to clean after and keep better. For picking, several rows of boards running the length of the house will be necessary. These should be nailed to posts driven into the ground before the house is filled. Short lengths of board that can be moved about are placed across the rows. The mushrooms should be given a twist when they are plucked and laid as near the long boards as possible. Boys with two boxes each then work behind the pickers, cutting off the stalks into one box and putting the mushrooms into the other. In this way they reach the packing shed free from dirt, and give a minimum of trouble. The old stumps should be left till they are shrivelled, when they will come out easily, the holes being filled with good soil at the same time. This helps greatly to prolong the life of the bed.
If the beds are to be in cold houses or pits, they must be 10 to 12 in. deep in the winter, and laid down and trodden in two separate layers; otherwise the procedure is the same as above.
Long rolls of stout brown paper, or canvas laid on wires inside the houses, also help to equalize the temperature and prevent radiation of heat. The idea of this is not to shut out the light but to maintain the atmosphere even in temperature and moisture.