198 
condition of the sides of the pots ; whence the common practice 
of plunging them in the earth, for the purpose of bringing 
them into the condition of plants gi’owing in the open ground. 
This is, however, attended with some disadvantage; for the 
plants root, through the bottom of the pots or over the edges, 
among the earth in which they are plunged; and, when 
taken up in the autumn for removal into the greenhouse, they 
must have all such roots cut off again ; for there are no means 
of bringing them within the limits of a pot. For these and 
similar reasons, no good gardener will expose his greenhouse 
plants to the open air in summer, if he can help it; unless they 
are duplicates, or unless there is some object to be attained 
very different from the strange notion that they are hardened 
by this process. The effect that is really produced upon them 
is, to give them a sort of artificial winter in summer, that is, to 
expose them to a period of comparative rest from growth, 
which, in many cases, is useful. The best method of counter- 
acting the injurious effects of exposure to the air is by employ- 
ing double pots, the space between the two pots being filled up 
with moss, or any other substance retentive of moisture. 
To be managed perfectly, a plant, when young, should be 
placed in as small a pot as it will grow in, and it should be 
gradually and successively transferred to larger pots as it ad- 
vances in size. If this is done, the warmth to which the pot is 
exposed will be more immediately felt by the roots; the latter, 
as they grow, will ramify regularly all through the mass of 
earth, which, moreover, will be thoroughly drained : but, if, on 
the other hand, a very small young plant is placed at once in a 
large pot, and left to grow there, the drainage will be less 
perfect, the large mass of earth will be less sensible of the heat 
to which it is exposed, the roots will from the first take a 
horizontal direction towards the outside of the pot, and, once 
there, will follow its surface as has been already stated, 
exhausting the small quantity of earth with which they are then 
in contact, and profiting little or nothing by the main body of 
soil in the interior of the pot. It is by paying constant atten- 
tion to the shifting of the growing plant, by the employment of 
a very rich stimulating soil, and by a thorough knowledge of 
the kind of atmosphere which suits them best, that have 
been obtained those magnificent Peljirgoniums, Cockscombs, 
