474 



PITS AND FRAMES. 



slips of wood nailed to the upright posts, 

 and kept 2 or 3 inches apart for the ad- 

 mission of a free circulation of air at all 

 times. Glass sashes are fitted on (a) to 

 keep the plants dry, and they are shaded 

 from the bright sun by canvass awnings, 

 b. Ventilation being so abundantly sup- 

 plied by the openings in the sides and 

 ends, the sashes may remain unmoved, 

 unless for the purpose of watering. Such 

 a pit might be rendered valuable also 

 during winter, if the sides and ends, in- 

 stead of having the slips of wood fixed to 

 the uprights, were made to open and shut 

 upon the principle of Venetian blinds or 

 louvre boarding. The frost would be thus 

 excluded from half-hardy plants, and 

 abundance of air can be admitted, which 

 is one of the principal considerations to be 

 kept in view in all arrangements for pro- 

 tecting plants during winter, as by that 

 means damps are corrected. 



All cold pits should face the north. If 

 they do not, the air in them gets heated 

 by the sun, and instead of the plants 

 being allowed to remain in a dormant 

 state during winter, they are first kept 

 growing to too late a period in autumn, 

 and afterwards stimulated into temporary 

 growth too early in the spring, which ren- 

 ders them much more liable to destruc- 

 tion from frost than if they were otherwise 

 circumstanced. They should also be kept 

 as dry as possible ; and no better medium 



can be found in which to plunge them 

 than coal ashes. The floor of the pits, un- 

 less the subsoil is gravel, should be ele- 

 vated a foot or 18 inches above the ground- 

 level ; and the walls should be 9 inches 

 thick, to exclude the frost. Where the 

 subsoil is dry gravel, there is no impro- 

 priety in keeping them on the surface ; 

 but by no means should they be sunk 

 under it. The necessity of keeping both 

 the soil, walls, and plants dry during 

 winter, is thus stated in the first volume of 

 the "Gardeners' Chronicle," p. 659—" This 

 necessarily seems to arise out of the 

 nature of vegetation, which, ^teing en- 

 tirely passive, cannot resist the influence 

 of surrounding media. If the air or soil 

 is damp, plants exposed to them must ab- 

 sorb the moisture ; but from the lowness 

 of the temperature of a winter house" — or 

 pit — " their powers of digestion and assi- 

 milation are torpid, and therefore the 

 water they receive, instead of becoming 

 incorporated with their system, stagnates 

 in their cells and cavities, where it be- 

 comes putrid ; and as soon as that takes 

 place, the evil extends with rapidity, 

 causing both branches and stems to be- 

 come rotten ; for decay in plants is always 

 contagious, and will spread through all 

 the parts with which it is in contact, until 

 the renovated forces of vegetation restore 

 the equilibrium of chemical constituents, 

 and thus arrest contagion." 



