AN ENCYCLOPEDIA OF HORTICULTURE, 



95 



Greenhouse continued. 



ing plants, each subject may be much better provided with 

 its special requirements, than when space for cultivation is 

 limited to the Greenhouse only. Here a certain tempera- 

 ture is maintained which suits a number of plants in flower, 

 but may not be warm enough for others that are making 

 their annual growth. If one house can be devoted more 

 especially to the exhibition of those plants in flower and 

 others with ornamental foliage, and they are changed as 

 becomes requisite, the interest in Greenhouse subjects will 

 be rendered more certain. This is, however, frequently 

 impracticable. 



Shape and Aspect. Plenty of light and air being essential 

 conditions for keeping in view in the construction of a 

 Greenhouse, it follows that the site chosen should be an 

 open one. The best shape is a span roof, as light is 

 admitted on all sides, and the plants are not so likely to 

 draw or grow in any one direction. Fig. 148 represents a 

 section of a span-roofed house well adapted for Greenhouse 



Greenhouse continued. 



Fio. 148. SECTION OP SPAN-ROOF PLANT HOUSE. 



plants. A centre stage is shown that may be made flat 

 if desired, for accommodating vigorous-growing subjects. 

 The side stages are on a level with the walls, and upright 

 sashes above these (a, a) are hung so as to open in the way 

 indicated. Top ventilation must also be provided, either 

 by sliding sashes, as shown in Fig. 149 (which, however, 

 have the disadvantage of admitting rain if open), or by a 

 more modern method which prevents this, by raising a 

 portion of the roof with a lever. A small lean-to hons 



J 



FIG. 149. LEAN-TO HOUSE. 



Fio. 150. HIP-ROOFED GREENHOUSE. 



well adapted for amateurs or others with only a limited 

 quantity of plants, is shown in Fig. 149. This might be 

 sufficiently heated by a very small hot water apparatus. 

 Hip-roofed houses (see Fig. 150) usually admit 

 light, but are not so convenient for attending 

 and arranging the occupants as the full span. 

 Again, ehelf stages are not so favourable to 

 good cultivation as flat ones, where a moist 

 bottom of ashes or small stones may be secured, 

 on which to stand the pots. Ventilation in 

 hip-roofed houses must be obtained by sliding or 

 a other movable sashes at the apex, and by small 

 doors inserted in the front wall. The aspect 

 best suited is one nearly south ; but, with the 

 full span, the ends should run north and south, 

 so that all possible light may be admitted, and 

 the sun's rays in summer somewhat obstructed 

 in the middle of the day. 



Greenhouse plants are divided into two 

 general groups, hard-wooded and soft-wooded. 

 r 1 rl , j Hard-wooded Section. This includes all 

 plants of a shrubby habit, and the majority 

 of climbers. A large proportion of them are 

 difficult to cultivate, particularly if their requirements 

 are insufficiently understood, and suitable positions are 

 not provided. The majority flower in spring and summer, 

 and proper treatment varies according to the condition 

 of the plants in 'such as the growing, resting, and 

 flowering periods. Healthy and floriferous hard-wooded 

 plants in spring, notably the numerous and beautiful 

 species from Australia and the Cape, are only secured 

 by constant attention throughout the preceding summer 

 and winter. Nearly all repotting should be 

 attended to just after the annual growth 

 begins, this season varying with different spe- 

 cies. A somewhat closer atmosphere, and 

 more moisture, may be allowed for a month 

 afterwards, to encourage the emission of roots 

 into the new soil. Afterwards, more air may 

 be gradually admitted, and, in bright summer 

 weather, a thin, temporary shading applied. 

 The aim, with hard-wooded plants, should be 

 to encourage summer growth to the fullest 

 extent, and to insure its thorough ripening 

 in autumn. Without this, the results subse- 

 quently obtained in the production of flowers 

 will be but secondary compared with what 

 is possible under good cultivation. There 

 are also numerous evergreen shrubs and 



