This section is from the book "Commercial Gardening Vol4", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
Of late years the Chicory (Cichorium Intybus) has become fairly well known, chiefly in the form of its blanched leaves, which when forced in warm dark places are known as Borbe de Capucin. There are several varieties, one of the best being the large-rooted or Brussels Chicory, the forced roots of which produce what is known as "Witloof" or "White-leaf" (fig. 504). To obtain good roots the seeds should be sown in nicely prepared soil in April or May, in shallow drills about 1 ft. apart. The seedlings should be thinned out about 1 ft. apart, and the ground should be kept free from weeds. From the end of October onwards the roots are lifted as required for forcing. The old leaves are removed and trimmed off within 1 1/2 in. of the top of the roots. Any side roots are also suppressed. The main roots being shortened to 8 or 10 in. are placed in trenches or boxes which are filled with rich gritty soil, so that the tops of the roots are 8 or 10 in. below the surface. They are then placed in the forcing chamber, or may be covered with a layer of hot manure, about 1 ft. thick, to encourage rapid growth. In three or four weeks yellowish heads of excellent flavour are ready for cutting, but care must be taken to secure them before the tips of the leaves touch the manure over them.
Fig. 504. - Witloof Chicory.