HOTBEDS AND GREENHOUSES 75 



at the bottom. Commence at the lower end by laying a wisp 

 of straw, cut ends out, on the string- at the bottom and fasten 

 it there by twisting each of the smaller strings once around 

 the straw and the upright strings. Next put on another wisp 

 of straw and so continue until the frame is covered. Mats 

 thus made are an admirable protection against frost, and far 

 better than shutters alone. The advantage of having shutters 

 in addition to the mats is that they keep the mats from getting 

 wet, which makes them so heavy that they break easily in 

 handling or they freeze solid and do not lie close or are 

 clumsy to handle. Rye straw r is best for mats and it is most 

 tough and durable when cut partially green. It is often 

 threshed by hand so that the straw can be kept straight, but it 

 may be cleaned by a threshing machine by holding the bundle 

 and only putting the heads into the machine. 



Ventilation and Temperature are subjects of greatest import- 

 ance in growing plants under glass. The various classes of 

 plants require different degrees of heat to reach their best de- 

 velopment. For instance: lettuce, radish, cress and similar 

 plants grow best at a low T temperature, say about 75 degrees 

 in the day and 40 to 50 degrees at night, w r hile tomatoes, egg- 

 plants, cucumbers and melons, grow best at a higher tempera- 

 ture, of 85 to 90 degrees in the day and 60 degrees at night. If the 

 former plants are kept at a higher temperature than that given 

 they are liable to become diseased and infested w r ith insects. 

 This is especially true of lettuce. On the other hand if the 

 high temperature plants are kept much cooler they become 

 sickly and weak, although tomato plants will grow in quite 

 cool temperature. In admitting air to glass structures care 

 should be taken that the wind does not blow in on the 

 plants. This is generally best accomplished in hotbeds 

 and frames by blocking up the sash at the ends or sides with 

 notched pieces of wood. 



The temperature of any place, unless otherwise specified, is 

 the temperature there of a thermometer in the shade. A 

 thermometer with the full sunlight shining on it, will record 

 about fifteen degrees higher than in the shade, which is a 

 point always to be borne in mind in ventilating. 



In the weather of early spring when the sun is getting 

 high, the middle of the days will be very warm and the nights 



