116 VEGETABLE GARDENING 



(3) The glass should be as close to the beds as it can be 

 and allow room to manage the crops grown in them. It 

 should be of larger size for greenhouses than for hotbeds 

 and in size not smaller than 10x12 inches, laid on sash bars 

 11 inches apart. The larger the glass the better. There 

 is not so much breakage in large as in small glass. 



(4) A permanent water supply is very desirable. 



(5) The glass should be of good quality, free from 

 blisters, bad waves, or other imperfections, and be what is 

 known as double-strength glass. 



(6) The heating arrangements should be sufficient to 

 heat the house easily in coldest weather; in other words, 

 it should be more than sufficient to maintain the proper 

 temperature if crowded. 



(7) Having the heating plant insufficient and then 

 crowding it in severe weather, injures the heating plant 

 and wastes fuel besides being a trial of patience. 



(8) The ventilators should be large and carefully fitted 

 so they will close tightly. When in the roof they should 

 be open at the top. If they open at the bottom the moisture 

 that condenses on the glass forms an ice ridge on them in 

 cold weather and prevents their shutting tightly. 



(9) The smaller the sash bars and framing material in 

 the roof the more sunlight can reach the crop. 



(10) The greenhouse roof may be covered with movable 

 sash, but it is generally found most desirable to use per- 

 manent sash bars. Where severe hailstorms are frequent it 

 might be well to use movable sash and take them off in 

 the summer, but such places are rare exceptions. It re- 

 quires a very severe hailstorm to break double strength 

 glass, when at an angle, as in a roof, and practically there 

 is little risk from this source. 



