REGULATION OF TEMPERATURE 27 



to open the upper ventilators rather than those at the side. 

 The chief trouble comes in the early days of spring, especially 

 if we are ill-provided with blinds. Then the thermometer is 

 apt to rush up to 80 or so, on the slighest hint of bright 

 sunshine on the glass, while a keen wind may be blowing 

 from north and east. It is often hard enough, under cir- 

 cumstances like these, to know how to regulate the tem- 

 perature. The temptation is to open side-lights as well as 

 roof ventilators and to let in all the air we can, for scorching 

 heat is as bad for hardy plants as frost for those that are 

 half-hardy, yet even hardy plants under artificial treatment 

 easily " catch a chill " at the roots in this way, from which 

 they may never recover. At such a moment we find our- 

 selves on the horns of a dilemma, and very much inclined 

 to sympathise with the pitiable case, near akin to our own, of 

 the gardener of whom Mr. E. V. Lucas tells us, who wrote 

 to his employer : " I'm varry sorry to tell you that I cant do 

 enay thing with the greenhouse. I think he will kill every 

 plant I have sometimes he will get varry hot and another 

 time I cant get enay heat in him and we cant stope him from 

 smoking so I doant know what to do with him " ! Happily 

 the troubles of the cold-house gardener are in great 

 measure simplified, and if the ample provision which is so 

 essential be made for ventilation, experience will soon teach 

 the necessity of avoiding draught. Only let it be remembered 

 at the same time that a stuffy stagnant atmosphere, per- 

 sisted in for a few days only, will surely set up an invasion 

 of that very infectious complaint " damping off." 



For eight months of the year it is scarcely possible to 

 give too much air, and where it may chance that a glass- 

 house is chiefly used for the shelter during winter of half- 

 hardy shrubs, or Roses planted out, it is an excellent plan to 

 have it so built that the lights can be altogether removed 

 when required. Of late, portable houses on rails for forcing 



