Mushrooms may be grown with ease in the open air in gardens; and this is a phase of the culture with which gardeners are not by any means sufficiently conversant. In fact, mushroom-culture in the open air in private gardens may be said not to exist at present, so very rarely is it seen.

In a little pamphlet on mushroom-growing that has lately appeared I find it stated that mushrooms may be grown out of doors “in summer,” but nothing about them being grown in the open air in winter. The Paris growers never attempt their culture in summer: the London ones very rarely. It is in winter that their cultivation is carried on in full vigour in the open air. Abundant crops are grown in the open air by the market-gardeners of London and Paris. From their beds mushrooms are gathered in quantities in mid-winter as well as in autumn. The Paris market-gardener does not attempt the culture in mid-summer, and does not think it practicable; but in the hot summer of 1868, and in the midst of the heats of July, I found about half an acre of ground at Brompton covered with mushroom-beds bearing well.

The following illustration is from a sketch taken in Nov. 1869, in market-garden fields, between Kensington and Brompton. The beds, about three and a half feet high and the same in width at the base, are covered with the long straw or litter taken from the stable manure. Over that is placed old bast mats, or any like materials, to keep the litter in its place, and throw off the rain; the mats being kept in place by tiles, bricks, old boards, or any like objects that may be at hand. This is well shown in my illustration.

The manure employed is that brought from the London stables, the longer litter being shaken out and put on one side to cover the beds. No care whatever is taken in the preparation of the manure; it is usually made into beds soon after it is brought home and before it is allowed to heat, and then the beds are made in the form of potato-pits and beaten very firm. The beds are spawned when at about a temperature of eighty degrees, the pieces of spawn being placed about a foot or so apart, and it is then immediately earthed, the ordinary soil being used, and the bed covered to a thickness of a couple of inches. The success attained by the market-gardeners of both London and Paris, with the ordinary soil of the place in which the beds may be made, well proves the absurdity of seeking for any particular kind of soil for covering mushroom-beds. Beds made in this way in the autumn and winter months, and covered with a thick layer of litter and mats, seldom require any watering. The culture is not usually attempted in summer; the heat acting upon the littery covering giving rise to insects which destroy the mushrooms; but with care their culture is quite practicable at that season; in proof of which I may say that during the last week of July, 1868, I saw them gathered freely in a market-garden just beside the Gloucester Road Station of the Metropolitan Railway, where by using a coating of litter about a foot thick, and over that a layer of mats, it was possible to procure them in good condition throughout the hottest summer within memory. There are many acres of ground covered with beds made thus in the market-gardens round London.

We will next turn to the culture of the mushroom in the open air near Paris. In old times the market-gardeners there used to grow it amongst their ordinary crops with great profit, but since the champignonnistes cultivate it under no danger from cold in the caves, the market-gardeners, who used to raise it to a great extent in the open air, do so now in a less degree. They begin with the preparation of the manure, and collect that of the horse for a month or six weeks before they make the beds; this they prepare in some firm spot of the market-garden, and take from it all rubbish, particles of wood, and miscellaneous matters; for, say they, the spawn is not fond of these bodies. After sorting it thus, they place it in beds two feet thick, or a little more, pressing it with the fork. When this is done the mass or bed is well stamped, then thoroughly watered, and finally again pressed down by stamping. It is left in this state for eight or ten days, by which time it has begun to ferment, after which the bed ought to be well turned over and re-made on the same place, care being taken to place the manure that was near the sides of the first-made bed towards the centre in the turning and re-making. The mass is now left for another ten days or so, at the end of which time the manure is about in proper condition for making the beds that are to bear the mushrooms. Little ridge-shaped beds—about twenty six inches wide and the same in height—are then formed in parallel lines at a distance of twenty inches one from the other.

In a market-garden they may stretch over a considerable extent, their length being determined by the wants of the grower. The beds once made of a firm, close-fitting texture, the manure soon begins to warm again, but does not become unwholesomely hot for the spread of the spawn. When the beds have been made some days, the cultivator spawns them, having of course ascertained beforehand that the heat is genial and suitable. Generally the spawn is inserted within a few inches of the base, and at about thirteen inches apart in the line. Some cultivators insert two lines, the second about seven inches above the first. In doing so, it would of course be well to make the holes for the spawn in an alternate manner. The spawn is inserted in flakes about the size of three fingers, and then the manure is closed in over, and pressed firmly around it. This done, the beds are covered with about six inches of clean litter. Ten or twelve days afterwards the growers visit the beds, to see if the spawn has taken well. When they see the white filaments spreading in the bed they know that the spawn has taken; if not, they take away the spawn they suppose to be bad and replace it with better. But, using good spawn, and being practised hands at the work, they rarely fail in this particular; and when the spawn is seen spreading well through the bed, then, and not before, they cover the beds with fresh sweet soil to the depth of about an inch or so. For cover, the little pathway between the beds is simply loosened up, and the rich soil of the market-garden applied equably, firmly, and smoothly with a shovel. With these open-air beds they succeed in getting mushrooms in winter. A covering of abundance of litter is put on immediately after the beds are earthed, and kept there as a protection. They have not long to wait till the beds are in full bearing, and when they are in that state it is thought better to examine and gather from them every second day, or even every day where there are many beds. And thus they grow excellent mushrooms, and in great quantity, all the further attention required being to renew the covering when it gets rotten, and an occasional watering in a very dry season.

Of course this kind of cultivation is perfectly practicable in private gardens—where, however, I have not yet seen it carried out. Where there is a mushroom-house or empty shed in which mushrooms may be grown, there would be less occasion to pursue it, but there are many places in which no such conveniences exist. In any case it is desirable that gardeners generally should know to what a large extent this phase of the culture is pursued round London and Paris, and how simply it is done. Instead of mats, it would be an improvement to cover the beds with tarpaulin or some other cheap material that would keep out the wet.