68 THE USE OF GLASS 



The watering of plants under glass should be carefully done. 

 Water should be applied only as frequently as is necessary to 

 keep the plants growing properly; but whenever water is applied 

 it should be put on in sufficient quantity to soak well down to 

 the roots of the plants. Infrequent, heavy waterings are better 

 than frequent, light waterings. The frequency of watering re- 

 quired will depend greatly upon the amount of sunshine and the 

 humidity of the atmosphere. In damp, dark weather, watering 

 should be withheld as much as possible in order to avoid danger 

 of damping-off and other fungous troubles. Care should be exer- 

 cised to have the foliage of the plants dry at night. It is also con- 

 sidered better to apply water to plants under glass when the 

 temperature is rising rather than when it is falling. Therefore 

 watering in greenhouses and hotbeds should usually be done in 

 the morning rather than the afternoon, especially in winter 

 weather. 



Tillage of Plants under Glass. — Plants growing under glass 

 respond to tillage the same as plants outside. The repeated water- 

 ing packs the soil, and it should be loosened up. Tillage with 

 hand weeders and similar tools should be given at least once a 

 week to all plants that are planted in such a way that tillage is 

 feasible. Of course, seedlings growing thickly in fiats, from broad- 

 cast seeding, could not very well be tilled. 



Shifting Young Plants. — Young plants started under glass for 

 later transplanting often require one or two shiftings before they 

 are ready for the final transplanting to the field. If the seeds have 

 been sown in flats, the young seedlings, as soon as they are large 

 enough to handle, may be shifted to other flats or to small pots. 

 This gives them space to develop into strong, stocky plants. 

 Sometimes, instead of being placed in flats or pots, the young 

 seedlings are set directly into the soil of a hotbed or coldframe. 

 Under the controlled moisture conditions there is little danger of 

 losing any of the plants. 



QUESTIONS 



1. What are the three kinds of glass structures used in vegetable growing? 



2. What are the uses and limitations of coldframes? 



3. What cheaper covering is sometimes substituted for glass on coldframes? 



4. How does a hotbed differ from a coldframe? 



5. What is the most common source of heat for hotbeds? 



6. What other means of heating hotbeds are sometimes employed? 



