Evils of exposing Green-house Plants during Summer. 31 



Art. IX. Considerations on the evil Effects of exposing Green-house 

 Plants to the open Air of Britain during the Summer Months. By 

 Mr. Robert Marnock. 



Sir, 



The practice of turning green-house plants out of doors in 

 summer may be necessary under particular circumstances, and 

 with regard to certain species of plants; but, in cases where 

 green-houses are properly constructed, and solely devoted to the 

 cultivation of plants, these will generally be found to be injured, 

 rather than benefited, by this treatment; particularly when 

 turned out early in the season. Were it possible to manage 

 green-house plants during the winter as it could be wished, and 

 as they require, exposing them to the open air in summer would 

 no doubt be highly beneficial to them ; but, from the changeable- 

 ness of our climate, and the frequent (though often unnecessary) 

 application of fire heat, to guard against the sudden attacks of 

 frost, a considerable degree of excitement is induced, and, before 

 the season has arrived at which they can be safely exposed to 

 the open air, they are all, or nearly all, in a state of vigorous 

 growth. Without regard to this circumstance, they are at once 

 removed to their summer quarters, when, although the frosty 

 nights may have gone by for the season, the temperature during 

 the night is often so low that a complete check is given to their 

 growth, from which they seldom recover till towards the approach 

 of autumn; when, after having I'egained their energy, and become, 

 as it were, inured to their new climate, they once more make an 

 effort to grow. From the gross habit which they have, how- 

 ever, now acquired, together with the lateness of the season, the 

 shoots are seldom well matured, and the plants are, therefore, 

 in the worst possible condition to resist the effects of frost, 

 mildew, damp, and other causes by which green- house plants 

 are liable to be injured. But, when plants are retained under 

 glass during the summer, both the first and second growths are 

 l'ipened sufficiently early in the autumn ; and, unless very im- 

 proper excitement be applied, they will remain in a state of 

 comparative rest till the following spring, when their flowers 

 will be both more perfect, and much more abundant than such as 

 may have stood but the preceding summer. 



I do not wish to be understood as recommending green-house 

 plants to be kept crowded together in the house the whole of the 

 summer, in the way we generally find them to be in winter. 

 Duplicates and all the coarser and hardier kinds may very 

 properly be removed out of doors ; and these would, in most 

 cases, be sufficiently numerous to afford room enough for those 

 that are left, to stand without touching each other. During the 

 summer the whole of the movable sashes in the roof and front 



