562 



THE PRACTICAL GARDENER. 



the bottom of the pit or bed. The pots, when plunged into 

 the bed made of leaves alone, are apt to become loose, the 

 leaves binding together in heating, and thus shrinking away 

 from them, thereby exposing the roots to the air, and per- 

 mitting the heat of the bed to escape ; whereas, when plunged 

 in tan, saw-dust, or similar substitutes, this evil is obviated. 



The heat produced by oak, or other leaves, is uniform, mild, 

 and lasting, and seldom endangers the roots of the plants with 

 too much heat, which is an important object; and if the leaves 

 be put in, in good condition, they will keep up a sufficient tem- 

 perature in most cases for six months, and will not require 

 to be turned over so often as tan, or any other substitute, to 

 refresh the process of fermentation. This will save much 

 trouble and expense, preventing also the necessity of exposing 

 the plants to heat and cold, by moving them about from one 

 place to another. The roots of the plants will also penetrate 

 through the holes in the bottom of the pots, and extend them- 

 selves a considerable way into the bed of half-decayed leaves. 



From the appearance of the roots of these plants, we might 

 naturally suppose that the plants derive nourishment from the 

 half-rotten leaves, and also from tan in a state of decomposi- 

 tion; although A. Young, Esq., in his Essay on Manures, 

 says, that spent bark seems rather to injure than assist ve- 

 getation, which he attributes to the astringent matter it con- 

 tains ; but every cultivator of the pine must have observed with 

 what seeming pleasure the roots of these plants penetrate into 

 half-rotten tan, as well as into leaves in a similar state of de- 

 composition ; indeed, many excellent cultivators root their pine 

 plants in rotten taix only. Oak-bark is certainly highly charged 

 with astringent properties, but is freed from that property by 

 the operation of water in the tan-pit ; and if injurious to vegeta- 

 tion, the effect is probably owing to its agency upon water, or 

 to its mechanical effects. Many of our more rare Alpine plants 

 thrive in rotten tan, when they will live in no other prepara- 

 tion which we can make for them. 



Where tan cannot be very readily obtained, oak or other 

 leaves are equally good for the fermenting purposes in the pine- 

 pits ; and, indeed, where it is even to be conveniently procured, 

 we would recommend a mixture of both, as affording an ex- 



