Where there is no, can be raised much earlier on a protected hotbed than in the open ground, and so plants are a week or two ahead of those from sown in the open. Sow the on the surface soil of the hotbed, give protection from frost, give air on warm days, and when in fourth harden for transplanting to cold frame, or if late spring, to the open ground.
To make a hotbed, dig out a square 6 ft. each way (or such size as will suit individual requirements) to a depth of 3 ft. Make the bottom firm, lay on stable manure, out of which the first fierce heat has gone, till level with the ground, then surround with a wooden frame, and Jet settle for a day or so. Then put a layer ofor grass and top the lot with fine earth to form a seed-bed, press down and level off to 6 in. below the top of wooden frame, cover with the glass top of a cold frame. In this the seed will grow quickly, especially half-hardy varieties. If an old window-frame, still glazed, is available, the whole thing could be made to adjust to it in size.
When all the earlyrequired have been raised, the frame and light can be removed (and used elsewhere as a cold frame) and vegetable marrow sown in May. They will germinate without protection and flourish in the richness of the hotbed. The life of a hotbed is not more than a month and a half. Don’t start it too early — begin say February or March, according to locality — so as to have its benefit till frosts are over. 8 in. of soil will suffice.