152 ROYAL BOTANIC GARDENS, KEW 
The question of drainage, too, is very important. In houses of 
this kind, where all, or nearly all, the plants are planted out, a frequent 
Dra' e f m ^ s ^ a ^ e * s °I ma king the beds of soil too deep, 
the Soil Lor s * ron &> coarse-habited plants like some palms this 
does not matter, but it is fatal to the permanent well- 
being of many delicate-rooted plants such as are grown in this house. 
In plant-houses, soil not permeated with roots is apt to become heavy 
and sour in a degree that never occurs in the open air. The only 
way to obviate this is to keep the soil as shallow as is consistent with 
the requirements of the plants, and to secure perfect drainage. When 
the two wings were being prepared for the reception of the plants, 
the bottom of each bed was laid with ordinary drain-pipes arranged 
to carry the surplus water right out of the house. Above these was 
laid a two-foot layer of brick rubble, leaving from 2 to feet to 
be filled with soil. This is ample for all but the largest trees, such 
as the Araucarias, etc., in the centre beds of the Winter Garden. For 
many plants eighteen inches are sufficient. When the Winter Garden 
was overhauled a few years ago, the beds, wherever possible, were 
treated similarly. The present remarkable health and vigour of the 
plants in this division is largely due to this policy and to the provision 
of more light when the building was re-roofed. These two things 
combined have also enabled many delicate plants to be cultivated here 
with success for the first time. 
We now proceed to give some notice of the more remarkable features 
and more notable plants in the different sections of this house. The 
digression into the general principles that should govern 
and Plant *he construction of conservatories of this class is, how- 
houses ever, justifiable ; for it is becoming a very popular class 
of plant-house, but even in these days is not always 
built in accordance with the most scientific principles. This is 
especially the case with winter gardens and conservatories built by 
public authorities in city parks and gardens. Here the matter is 
usually put into the hands of an architect quite ignorant of the re- 
quirements of plant-life, whose sole object is to produce an agreeable 
or imposing effect from outside. No doubt the architect’s aim is 
a worthy and even an important one, but the lavish use of stone 
and other opaque building materials in a plant-house is opposed 
to the well-being of the plants it contains. Such materials should be 
reduced to the smallest limits consistent with the stability and dignity 
