CHAPTER XI 
CONSTRUCTION OF HOTBEDS 
152. The necessity of glass. — In nearly all types of 
vegetable gardening glass is essential to secure the best 
returns. It is true that many crops, as sweet corn, cab- 
bage, peas, beans and the root crops, are grown at a 
profit without the use of glass, although most gardeners 
regard it as indispensable for certain parts of their opera- 
tions. The term glass includes the. different types of hot- 
beds, cold frames, forcing hills and greenhouses. 
Glass is often used merely for protection, as for winter- 
ing plants in cold frames. The more common uses, 
however, are to hasten or forward the growth of plants, 
so the crops will mature before their normal time, and to 
grow crops to full maturity during the winter season, 
when it is not possible to produce them in the open in 
the same latitude. 
There are many advantages in starting certain vege- 
tables under glass, then transplanting to the open ground 
as soon as conditions are right. Some of these advan- 
tages are: (1) Crops placed on the market before their 
normal season usually command the highest prices. (2) 
In many sections the summers are too short to mature 
certain crops, such as eggplants, watermelons and late 
tomatoes, without the use of glass. (3) In starting the 
crop early there is less danger of loss by destructive 
frosts in the fall. (4) By forwarding the plants under 
glass, two or more crops can often be grown on the same 
land during the season. (5) Weeds are generally less 
difficult to combat when plants of good size are set in the 
open. (6) It may also be the means of avoiding trouble- 
some insects and fungous diseases. (7) Some vegetables, 
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