362 VEGETABLE FORCING 
not regularly supplied with cress from outdoor sources, 
find sale for a limited quantity. 
Water cress may be propagated from seed or cuttings. 
The usual plan in the greenhouse is to use cuttings 
which root very quickly in moist sand. The plants may 
then be shifted to flats and later to the permanent beds. 
Bottom heat is unnecessary. In fact, the plant does 
better in soil that is rather cool. The supply of soil 
moisture should be abundant and constant. Water cress 
may be grown under benches where there is fairly good 
light, or in any kind of a bed or a box provided with 
proper conditions. When well established, it will renew 
itself and require little attention, except watering. 
CELERY 
Celery is not regarded in any part of the country as an 
important forcing crop. It is possible, however, to grow 
good celery under greenhouse conditions, and the diffi- 
culties involved are probably no greater than in the pro- 
duction of some other crops—the melon, for example. 
Whether celery forcing will ever become an important 
commercial industry is extremely doubtful. A grower 
here and there is fairly optimistic concerning the out- 
look, but as a financial proposition there is not very 
much encouragement in the results of even the most suc- 
cessful greenhouse growers. In general, it may be said 
that celery requires practically the same conditions as 
lettuce, though it is far more exacting in its requirements 
of heat and moisture. 
Market opportunities seem to be best during the 
months of April, May and June, or after the stored 
supply has become exhausted. To mature the crop at 
that time, the seed should be sown the latter part of 
November or early in December. 
The so-called self-blanching varieties have been al- 
most universally employed and recommended for forcing. 
