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.
The next step is the laying down of the beds. Taking flat ones first, it may be stated that whether prepared in Mushroom houses, pits, or glass-houses, the method of laying down is the same, the only difference being in the depth.
It may be taken for granted that it is more economical to put down a bed of 6 to 7 in. in depth, using hot-water pipes to maintain the necessary temperature, than it is to make a bed 12 to 14 in. deep in a cold house, and having to cover heavily with litter for the same purpose. The latter method entails the shifting of the litter at each picking, and one is rewarded by an inferior quality of Mushrooms. The maker of the bed should have a stick marked at 14 and 7 in. for a 7.-in bed, which is a good average depth, or 12 and 6 in. for a 6-in. bed. The surface the bed is to lie on having been levelled, the outside of the heap should be cast on top as before, and manure thrown into a small heap in front of the larger. The barrows should then be loaded from this smaller heap, which will ensure good mixing. This point of thorough mixing cannot receive too much emphasis, for on it will depend the uniformity of the bed in moisture and temperature. The contents of the barrows should be tipped out a little way in front of where it is to be laid, in order to give the workmen a clear space. It should not be pitched down by the forkful, but thoroughly shaken and scattered, lightly pressing it down to the 14- or 12-in. mark, keeping the ground cleared up, and using the stick frequently to test the depth. Behind the workman laying down should come a man to tread the manure in a systematic manner, putting plenty of weight on the heels, and working in lines forwards and backwards across the bed. The following day the bed should be brushed over with the back of a fork and then trodden twice more, thermometers being inserted afterwards in various places. If they rise to between 70° and 75° F. during the next two days, and remain fairly constant, spawning may commence. It is not wise to leave the thermometers in a few places only, they should be shifted about several times: there may be a few hot places in the bed. Should the temperature exceed 80° it is better to wait a little. If it still rises, holes should be bored in the bed at intervals of 1 ft. and the surface lightly pricked up. As soon as it drops below 80° it is safe to spawn, but a bed that does not rise above 75° gives the best results. Care should be taken that moisture does not condense on the top of the bed; the surface should be roughed with a fork.
MUSHROOM BED AT ISLEWORTH.
Exposed for picking.
Photo. J. Weathers.
Photo. Chas. L. Clarke.