424 SCIENCE OF GARDENING. Part II. 



the watei given to the plants ; although the force of the season will sometimes prevail to 

 95 and 100." M'Phail, however, found that pines will bear without injury 1 30, and he 

 considers that no plant whatever will be injured by 1 20. " It is not uncommon to give air 

 to a hot-house only through the day, and to shut it up close at night, perhaps even increas- 

 ing the temperature in the evening. Judicious horticulturists reverse the practice. 

 Knowing, for example, that, in the West Indies, chilly and cold nights usually succeed to 

 the hottest days, they rather imitate nature, by shutting up the house during the day, and 

 throwing it open at night. This practice, however, can only be followed in our climate in 

 the summer and autumn seasons." (Neill, in Ed. Ency. art Hort.) This opinion is in 

 unison with Knight's, who considers exeess of heat during the night, as in all cases 

 highly injurious to the fruit-trees of temperate climates, and not at all beneficial to those 

 of tropical climates ; " for the temperature of these is in many instances low during the 

 night. In Jamaica, and other mountainous islands of the West Indies, the air upon the 

 mountains becomes, soon after sunset, chilled and condensed, and in consequence of its 

 superior gravity descends and displaces the warm air of the valleys ; yet the sugar-canes 

 are so far from being injured by this sudden decrease of temperature, that the sugars of 

 Jamaica take a higher price in the market than those of the less elevated islands, of which 

 the temperature of the day and night is subject to much less variation." (Hort. Trans. 

 vol. ii. p. 131.) 



Sect. VII. Operations of Protection from Atmosplierical Injuries. 



2206. The injuries which plants may receive from the atmosphere, are as various as its 

 changes. Many vegetables which flourish in Britain in the open air during the summer 

 season require protection during some or all of the other seasons of the year. Some also, 

 from the state of their health, or other circumstances, require to be protected from the direct 

 rays of the sun, from excessive rains, winds, frosts, and even from heat and evaporation. 

 From these and other evils the gardener protects by opaque coverings or shelters of different 

 kinds, and by transparent covers or glass cases, and by other operations and processes. 



2207. Protecting by fronds and frond-like branches is performed by sticking in the 

 foot-stalks of the fronds of any of the ferns, but especially of the pteris aquilina, 

 branches of fir, whin, or broom, or of any other evergreens, between the branches of wall- 

 trees and the wall, so as the frond or leafy branches may project, and either retard 

 the blossom by excluding the sun, as is often done in Denmark and Sweden, or protect it 

 from the frost and winds, as is generally the object in Britain. This is a very simple and 

 economical protection for myrtles, camellias, and other tender botanical plants, trained to 

 walls, or even growing in the open ground as stools, and also for fruit-trees. Archd. 

 Gorrie {Caled. Mem. vol. i. 276.) formed a frame for the more commodiously containing 

 the branches of spruce and silver firs, and other evergreens ; and applied frames so 

 clothed to his fruit-tree walls, on the principle of retarding the blossom. The success 

 was equal, and even beyond his expectations. He covered them on the 20th of February, 

 and removed the frames on the 1st of June. During this period, the frames were opened 

 every fine day, but always shut at night. Adjoining were some trees of the same kinds, 

 which were covered night and day, during the above period, with a woollen net. The 

 shoots of these trees were infected with the curl or wrinkled leaf a disease peculiar to 

 peach-trees in exposed situations '; while those protected by the frames of branches were 

 perfectly healthy ; and what is remarkable, though retarded nearly four weeks in the 

 period of their blossoming, the fruit ripened one week sooner. 



2208. The advantage of using frames in covering by fronds and branches is, that the screens or protecting 

 frames can be removed in the daytime ; whereas, attaching the fronds to the trees, they must, in general 

 remain till they have effected their object. It is easy to conceive that trees so treated must often suffer 

 from want of light, and accordingly Nicol, on the whole, rather disapproves of it. " It is," he says, " a 

 common practice, to screen the blossoms of wall-trees by sticking twigs of larch, or of evergreens, as 

 firs, or laurels, between the branches and the wall, in such a manner as to overhang the blossoms where 

 thickest ; and some, instead of these, use the leaves of strong fern. These last are certainly fitter for 

 the purpose than the former mentioned, as being lighter, and less liable to hurt the blossoms, when dashed 

 by the wind against them. But all these are objectionable, on account of their shading the bloom too 

 much, and too constantly, from the sun and light, by which it is rendered weak, and the fruit produced 

 often drop away, before arriving to anyiconsiderable size ; so that all this trouble taken goes for nothing, 

 as there would probably have been as good a crop, had the trees been left to take their chance." 



2209. Protecting by straw ropes is effected by throwing the ropes in different directions 

 over the trees, and sometimes depositing their ends in pails of water. It is a Dutch 

 practice, and appears to have been first made known in this country by Dr. Anderson, in 

 his Recreations, &c. in 1804. James Laird appears to have tried it successfully on wall- 

 trees, and on potatoes and other herbaceous vegetables. His method is as follows : 



" As soon as the buds of the trees become turgid, I place poles against the wall, in front 

 of the trees, at from four to six feet asunder; thrusting their lower ends into the earth, 

 about a foot from the wall, and fastening them at the top with a strong nail, either to the 

 wall or coping. I then procure a quantity of straw or hav ropes, and begin at the top of 

 one of the outer poles, making fast the end, and pass the rope from pole to pole, taking 

 a round turn upon each, until I reach the end ; when after securing the end well, I begin 



