36 THE UNHEATED GREENHOUSE 



to Orchid or even Pelargonium pitch. No less important is 

 it clearly to define our intentions to ourselves as to whether 

 we grow hardy plants only or whether we wish to include the 

 less hardy, for which a certain amount of heating power is 

 required, though not enough to render the term " unheated 

 greenhouse " a contradiction, inasmuch as it need be in most 

 cases merely a transient encumbrance and not a permanent 

 one. In either case some knowledge of plants and a hearty 

 desire to know more is inseparable from the true enjoyment 

 of this, or, indeed, any other branch of gardening. With 

 regard to culture, nothing teaches so much as practice, and 

 when the true gardening instinct exists the early stage of 

 helpless ignorance soon gives place to greater assurance, as we 

 take advantage day by day of every hint, spoken and written, 

 that comes in our way. Then as experience grows we begin 

 to make experiments on our own account, for there is no 

 doubt whatever that many plants may be educated and made 

 to adapt themselves to environments other than those that are 

 natural to them, and herein lies one of the many interesting 

 features of advanced work in a cold greenhouse. A generation 

 since, numbers of plants now commonly to be found in our 

 garden borders were grown under glass and reckoned too 

 tender to be trusted out of doors. The result of experiments 

 during many years in testing the capabilities of unheated 

 houses in my own garden proved to demonstration that a fair 

 proportion of plants will succeed admirably under good 

 management, and are less subject to blight and disease in a 

 much lower temperature than is usually supposed to be indis- 

 pensable to them. 



The same effects, it is true, may be traced as the result of 

 the different modes of treatment, as may be noticed in Switzer- 

 land between the plants of the valley and those of the bleaker 

 mountain-side the growth is not so rapid, and luxuriance is 

 restricted. But what is lost in these respects is made up in 



