434' Destruction of the Mealy Bug and Scale. 



would hardly be found to have varied one degree. With respect to 

 moisture, every cultivator knows, that, in a properly constituted and regu- 

 larly pulverised soil, whatever quantity of rain may fall on the surface, the 

 soil is never saturated with water, nor, in times of greatest drought, burnt 

 up with heat. The porous texture of the soil and sub-soil being at once 

 favourable to the escape of superfluous water, and adverse to its evapora- 

 tion, by never becoming so much heated on the surface, or conducting the 

 heat so far downwards, as a close compact soil. These properties of the 

 soil, relatively to plants, can never be completely attained by growing plants 

 in pots, and least of all by growing them in pots surrounded by air. In this 

 state, whatever be the care of the gardener, a continual succession of 

 changes of temperature will take place in the outside of the pot ; and, the 

 compact material of which it is composed being a much more rapid con- 

 ductor of heat than porous earth, it will soon be communicated to the web 

 of roots within. With respect to water, a plant in a pot surrounded by air 

 is equally liable to injury. If the soil be properly constituted, and the pot 

 properly drained, the water passes through the mass as soon as poured on it, 

 and the soil at that moment may be said to be left in a state favourable for 

 vegetation : but as the evaporation from the surface and sides of the pot and 

 the transpiration of the plant go on, it becomes gradually less and less so, 

 and, if not soon resupplied, would become dryland shrivelled, and either die 

 from that cause, or be materially injured by the sudden and copious application 

 of water. Thus, the roots of a plant, in a pot suri'ounded by air, are liable to 

 be alternately chilled and scorched by cold and heat, and deluged or dried up 

 by superabundance or deficiency of water, and nothing but the perpetual care 

 and, attention of the gardener, to lessen the tendencies to these extremes, 

 could at all preserve the plant from destruction. To lessen the attention of 

 thegardener5therefore,to renderthe plant less dependent on his services, and, 

 above all, to put a plant in a pot as far as possible on a footing with a plant 

 in the unconfined soil, plunging the pot in a mass of earth, sand, dung, tan, 

 or any such material, appears to us a most judicious part of culture, and 

 one that never can be relinquished in fruit-bearing plants with impunity. 

 Even if no heat were to be afforded by the mass in which the pots were 

 plunged, still the preservation of a steady temperature which would always 

 equal the average temperature of the air of the house, and the retention, 

 by the same means, of the steady degree of moisture, would, in our opinion, 

 be a sufficient argument for plunging pots of vigorous-growing, many-leaved, 

 or fruit-bearing plants. Had Knight's plan been brought forward by a less 

 eminent horticulturist, it would have claimed but little attention, as the 

 plan of growing pines without bottom heat is generally considered to have 

 been tried and to have failed." 



Mr. Knight, of the Exotic Nursery, King's Road, has seen 

 the pines in the garden of Mr. Knight, as well as those of 

 Mr. Dall ; and though we have no authority to refer to him, 

 yet he may be asked what he thinks of both -systems, and 

 what relation the plants at Downton and Wimpole bear to 

 those of the first pine-growers about London; say, for ex- 

 ample, those in the Royal Gardens at Kensington, or in Syon 

 Gardens. — Cond. 



