The Time for Planting 147 
Purdue Agric. Expt. Sta. 
Fic. 83. A group of home-made plant forcers. One is placed over each plant 
or hill of plants. It has a frame of wood andaglasstop. Each plant forcer is 
thus a miniature greenhouse or cold frame that can be removed as soon as warm 
weather arrives. In the illustration the forcers are being used on rhubarb. 
ing dates for the vegetables he wishes to grow in his 
own garden. 
TEMPERATURE REQUIREMENTS AND GROWING PERIODS 
OF DIFFERENT GARDEN CROPS 
Garden crops may be divided into cool-season and 
warm-season crops. ‘The seeds of cool-season crops ger- 
minate in the cool soil of early spring, and their seedlings 
are not much—if at all—injured by moderate frosts. 
The growing plants of this class thrive during cool 
weather, and most of them mature during the cool 
weather of either spring or fall. In the more south- 
ern states many of these crops are “ fall and winter ” 
crops, growing and maturing from September to 
May. 
