105 
BOTTOM HEAT. 
Having devoted some of the previous pages to the subjects of Heat and Light 
within the area of glass erections, we find it necessary to solicit the attention of 
our readers to other important subjects which have been brought within our 
notice since the publication of the last number. 
Bottom-heat has been considered as essential ever since the introduction of 
tender exotics to our gardens ; at one time, that is about the beginning of the 
present century, every hothouse plant, excepting those of the succulent tribes, 
was not only propagated, but kept plunged to the rim of its pot in a deep bed of 
tanner s bark ; and there it certainly prospered. But the cause, the philosophy 
of the luxuriant effects produced did not then enter into the speculation of the 
cultivator: at length, however, certain inconveniences became manifest; roots 
were rapidly formed, which, after filling and meandering in the pot, found a passage 
through the drainage hole at its bottom, and passed into the tan bed. Frequent 
removals and shiftings were required, and these tended to disturb and give a 
check, which neutralized the good effects of the previous treatment. Bottom-heat 
was therefore abandoned as an appliance of general hothouse culture, and the 
gardener, by substituting simple atmospheric heat and moisture, ran into the 
opposite extreme. 
Whatever may be said, pro or don, for the practice of plunging a rooted plant, 
(we say nothing here of propagation,) the admission must be claimed, that a vast 
deal is gained by surrounding a pot with some moist material ; because it is quite 
certain that tender roots are seriously injured by aridity of soil ; and many a plant, 
confined within a pot which has been thoroughly heated and dried by a parching 
sun, is seen to perish without chance of recovery. There are inconveniences in 
all things, and trouble attaches to all operations ; but we shall never bring flori- 
culture to anything like perfection, till we can safely provide our potted plants 
with some substitute for a bed of earth. The fact is proved by the luxuriance 
which invariably is produced by transferring to borders and parterres those plants 
that decorate our summer gardens. 
"We now come to the subject which has dictated the present article. Since the 
wide adoption of the hot-water tank system, we had flattered ourselves that 
bottom-heat, of the safest and most genial character, was absolutely at command ; 
that not only might we propagate, by cuttings, with assured success, but supply a 
degree of atmospheric moisture so regulated as to obviate injurious aridity of 
soil. But within a very short period doubts have been raised concerning the 
salubrity of the tank, and we are now credibly informed by those who should know 
the fact, (namely, the tanners themselves,) that gardeners, some at least, are 
recurring to the tan bed as a medium of heat, a substitute for the water-tank 
As yet we have not been able to collect materials of sufficient extent to leave 
VOL. XII. — no. cxxxvii. p 
