FORCING, in gardening, is a term used to designate a process in which artificial heat is applied so that flowers, fruits or other prod ucts of plants are obtained at a date or season other than that at which they may be had in the ordinary course of culture. Thus, for ex ample, kinds of grapes which by the simple influence of the heat of the sun in a vinery do not ripen till September or October are in duced by forcing to ripen in March or later, according to the period the process is com menced; and strawberries, which ripen from June to September, in the. forcing-house yield their fruit from February onward. Conducted, as the system is, during the short days of the year, the chief obstacle the gardener has to contend with is diminished light. This in the case of forcing fruits taxes his skill to the utmost, because abundant light is essential both to the proper fertilizing of the flowers and to the perfecting of the fruit. Some vegetables
and salads and many flowers are, however, more successfully forced in the dark than in light. Rhubarb, seakale, mushrooms, lily of the valley, lilac, are all forced in greater or less darkness. A hotbed of fermenting manure is used to force rhubarb. Among flowers, roses, carnations, lilies of the valley, azaleas, deutzias, violets, mignonette and sweet peas are those most commonly forced, along with such bulbs as hyacinths, tulips and narcissi. By the application of an atmosphere containing ether, the forcing of certain flowers, particularly lilacs, has been much accelerated, and a quick and regular development secured, but the proc ess is yet in an experimental stage. Consult The Forcing Book,' by L. H. Batley (1897); 'Greenhouse Construction and Greenhouse Management,' by L. R. Taft (1903) • W. J. May's 'Greenhouse Management' (3d ed., 1900).