ON FORCING VEGETABLES. 
115 
I shall not attempt to treat of the cultivation of Pine- 
apples Grapes, Cherries, or other fruits grown in forcing- 
houses j nor would it be advisable with us to undertake to 
raise Cucumbers, Melons, &c., in frames throughout the se- 
vere winters of our Northern States ; but it must be acknow- 
ledged, that the extreme heat of our summers is as detri- 
mental to the cultivation of some of the most valuable kinds 
of fruits and vegetables, as the coldness of our winters, and 
for these reasons, artificial aid is more necessary here in the 
winter and spring of the year than in England. The inhabi- 
tants of that country obtain a supply of the different varieties 
of Artichokes, Broad Beans, Borecole, Broccoli, Cauliflower, 
Kale, Lettuce, Radishes, Rhubarb, Spinach, Turnips, and 
salads in general, a great part of the year from their kitchen 
gardens, whereas, if we were to attempt to supply our mar- 
kets with culinary vegetables at all times, in any thing like 
the abundance that they have them there, we must, out of the 
ordinary season for gardening operations, turn our attention to 
the protecting and forwarding, as well as the forcing system. 
Before I proceed to show the method of forcing vegeta- 
bles, it may be necessary for me to remind my readers, that 
in providing an artificial climate, they should consider the 
nature of the plants they intend to cultivate, and endeavour 
to supply them with that which is best calculated to nourish 
and support them. I have, in another part of this work, 
endeavoured to show, that heat, light, air, and moisture, are 
each essential to vegetation, and that these should be sup- 
plied in a judicious manner, according to circumstances. 
In the midst of our Northern winter, which is the usual 
time for forcing in England, we are subject to north-west 
winds, which produce extreme freezing. Now, as we have 
not yet discovered how to make an artificial air, it will not 
be safe for the gardener to raise a bottom heat under any 
kind of vegetable, until such time as he can impart a tole- 
rable share of salubrious air, as the heat without air will 
soon destroythe fruits of his labour. 
