Grapes have been cultivated in the Cognac region of France since the earliest historical times. The cultivation appears to have been introduced concurrently with that of wheat. All common methods are in use in the preparation of the field for the vineyard. In some cases the work is done by hand, in others by the plow, and in still others by a steam engine. In each case it is important that the ground be deeply stirred before the vines are planted, in order that the hard layers underneath the surface may be broken up to permit an entrance of the roots. The vine, however, is a hardy plant and will seek its nourishment even in the most unpropitious localities, sending its roots deep in between the rocks, if necessary, to get the required nourishment. It is desirable that the vine shall yield a crop as soon as possible after planting, and this is usually secured in three years; but the greatest care must be taken in the setting of the vines, in cultivation and in fertilizing. The soil is often broken up to a depth of half a meter, or even more. The surface is brought into a fine condition of tilth by harrows and other apparatus. Where the vine is planted in stony land, of course, the preparation is more laborious.