CHAPTER 5 



MOISTURE AND WATER REQUIREMENTS 



Moisture here means the humidity present in the 

 hothouse atmosphere. The importance of this sub- 

 ject is as yet little appreciated by the practical man. 

 The investigations of Blake* on the moisture re- 

 quirements of roses point to the urgent need of 

 similar experiments, on other commercial hothouse 

 crops. 



In the greenhouse, temperature and humidity rank 

 with food in their importance to the plants. 



Ejfect of Humidity on Rose Foliage. Frequently 

 when a greenhouse crop fails, the soil, the fertilizer 

 or the water receives the burden of the blame. Lit- 

 tle does it occur to us that the cause of the failure 

 may be due to improper adjustment of humidity to 

 temperature and watering. That each crop requires 

 diflFerent humidity conditions is well conceded. The 

 maidenhair fern, for instance, will not thrive in a 

 house with a dry atmosphere, a condition which is 

 ideal for other plants such as ornamental cacti. 

 With roses a low humidity tends to reduce the size 

 of the leaves, and the latter become "hard" and 

 lose their flexibility. Again, vigorous, dark green 

 foliage indicates a proper degree of humidity. 



•Blake, M. A., New Jersey Agr. Expt. Sta. Bui. 277: 3-55, 191s- 



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