Forcing House
The quantities of cut flowers and plants required in many gardens, render it a necessity to either build or set apart a special structure for forcing purposes, with provision for those subjects needing bottom heat, and a bed or staging for others that are better without. A Forcing House is also, sometimes, specially reserved for such plants as Strawberries, where they are placed in a high temperature, after flowering is over, for the purpose of swelling and maturing the fruit. A span-roofed building is most suitable for accommodating plants of various heights, and is, at the same time, one that admits most light. If provided with a glass partition, and separate valves in the heating arrangements, an advantage is gained of keeping one part a little cooler than the other, and introducing plants into this when first starting them. The Forcing House should be in a sheltered position in the garden, but not so as to be shaded in winter; and it should have plenty of heat at command. A span-roofed structure admits of a centre stage with path round, and side beds under which pipes could be placed for bottom heat; or, in the case of a small one, the path may be through the centre, and beds arranged on either side. All plants may be stood near the light, in a house of this description, by raising or lowering them according to height, but this condition could not be procured so readily in one of another shape. Stronger and more equable bottom heat is obtained when the pipes pass through a shallow water tank underneath the plunging material. A span-roofed house, about 30ft. long, 16ft. wide, and 9ft. high, would allow considerable space for plants of various sizes, and would be most desirable for other purposes, when not required for forcing. A minimum temperature of from 50deg. to 55deg. is preferable to a higher one for starting most flowering plants not requiring bottom heat. This may be raised 10deg. after growth commences. Much must depend, in forcing, on the condition of the weather outside. Light syringings, with water as warm as the house, may be given on bright days, and all possible sun heat should be retained in the winter and early spring months, when forcing operations are of the greatest importance. The admission of air by the ventilators must be conducted with great care, when it becomes necessary to open them, on account of the tender foliage or flowers. A change of air takes place continually between the laps of the glass, particularly when the outside temperature is much lower than that inside. Fire heat should be stopped in the day-time, so soon as the sunshine is strong enough to give sufficient warmth without it.