COLD AND ALPINE PLANT HOUSES 



Most low-roofed houses serve well, but as winter 

 flowering crocuses and irises love what little sunshine 

 there is going during the winter, a north aspect is not 

 favourable. All the plants grown in these houses are 

 uninjured by frost, but their flowers are apt to be 

 destroyed by severe spells of cold. Mats are useful for 

 covering the roof, but if a range of heated houses is 

 close by, it is certainly worth while to run a couple of 

 4-inch pipes round the cold or alpine house. Valves 

 should be attached to the pipes at their entrance to the 

 house, so that the pipes need only be heated when the 

 temperature sinks below 38 degrees, and even then a 

 slight warmth in the pipes is usually sufficient. With 

 artificial heat, the day temperature should not be above 

 40 degrees, but on sunny days this will be exceeded 

 without artificial heat, and such weather is, of course, 

 just the thing to bring the many beautiful flowers that 

 may be grown here to perfection. During fine mild 

 days abundant ventilation is required. 



The best effect is gained when miniature rock work 

 is built either on, or wholly instead of, the formal stages 

 of the greenhouse. The pockets between the rock are 

 filled with either earth, sifted coal-ash, or cocoa-nut 

 fibre, and in this material the plants are easily plunged, 

 and replaced by others as they pass out of flower. The 

 surface of the pocket soil should be surfaced with living 

 moss. For small rockeries virgin rock may be used. 

 In cases where the rock work descends to the floor level, 

 48 



