190 JOUENAL OF THE EOYAL HORTICULTURAL SOCIETY. 



at the number that can be well grown outside, instead ot" inside, tlic 

 plant-houses in which they might be expected to be containetl. 



It may be interesting to mention that for many years experiments 

 have been made in the Cambridge Botanic Garden which help to answer 

 the question, and it is not too much to say that the tender plants 

 growing out of doors would require, i'f grown under glass, quite the 

 largest of our plant-houses or even more than that, so that much space 

 is saved. Such experiments are not exclusive to Cambridge, but there 

 is always the possibility of something new or different or fresh in appli* 

 cation, and I think that Cambridge has done something to illustrate 

 the way to utilize the shelter and warmth naturally provided by plant- 

 houses, ,and especially how to succeed with such groups, for instance, 

 as the so-called hardy Cacti. These have been a feature for some years, 

 and other natural groups of some particular interest are the Zingi- 

 beraceae or Ginger family, and the Bromehaceae or Pineapple family. 

 Certain particular plants too, the results of trial, have been noteworthy. 

 I may mention that Gerhera Jamesoni planted against the south wall 

 of a stove behind Cacti had leaves 2 feet long and flower stems 3 feet 

 high, with flowers inches across, in the early days of its cultivation, 

 when it was considered difficult to grow. 



All the warm corners at Cambridge are included within what I 

 may term the Eiviera region of that garden. It is formed by the 

 plant-houses. We have first of all a corridor over 90 yards long and 

 16^ feet high running east and west. Opening out from this corridor 

 on the south side are the plant-houses, each one 9 feet apart from its 

 neighbour. There is thus protection from the north by the corridor, 

 and protection from east to west, for recesses and spaces between 

 the plant-houses, by the houses themselves. All the front of the 

 range is open to the south. There is in winter the important factor 

 of warmth from the plant-houses, especially those that have four hot- 

 water pipes on the inside of the walls. These pipes, I believe, keep 

 the narrow borders next the walls from sinking to a very low tempera- 

 ture, and of course protection can be given in various w^ys. Even 

 a slight amount of shelter and protection sometimes makes a great | 

 difference. Whether a plant is tight against a wall or only a few inches 

 away from it may be of consequence. 



During severe weather in winter mats are used to protect the more 

 tender shrubs that are planted against walls or glass, and light litter 

 is effective for lower growths. Nothing is more suitable than bracken, 

 for it does not readily sink into a wet mass. All protection should 

 be as dry as possible. For the purpose of keeping off wet, movable! 

 lights are used over the Cacti, the Caper plant, and a few others. 

 Mats in front of the more tender Cacti, like Opuntia rohusia, afford 

 still further protection to them. Ashes are quite satisfactory over 

 bulbs, tubers, and rootstocks at rest, but care must be taken to remove 

 them before much growth takes place. Anything wet or rotting makes 

 a very bad protection. 



