66 THE BOOK OF THE GREENHOUSE 



is almost too small to be seen by the naked eye, but 

 its presence is readily detected by the rusty marks it 

 makes on leaves and stems. Directly these marks are 

 seen, the house must be fumigated or vaporised with 

 nicotine, and this should be repeated about three times 

 on alternate evenings. 



Cannas. Handsome even as foliage plants, these have 

 been much improved of late as regards freedom of flower- 

 ing and size of flower. Some of the newer varieties are 

 quite gorgeous and even startling in their daring mix- 

 tures of colour. They are easily grown, but require 

 quite a rich and porous soil in which to develop at their 

 best. The root stock should be divided in spring into 

 pieces, each containing one or two crowns, and potted 

 up in equal portions of good loam, sand, and decayed 

 cow manure, using well drained pots, seven inches to 

 ten inches, according to the size of clump, as Cannas re- 

 quire an abundance of water when growing. They may 

 be grown in the cool house, but are grateful for more 

 heat if feasible ; and with increased heat should be in- 

 creased humidity of atmosphere. They flower from 

 July to November, according to the variety grown and 

 the time of starting the clumps, for in this they are very 

 accommodating. After flowering, reduce the water sup- 

 ply, and, when sufficiently dry, remove to a dry frost 

 proof shed till potting time comes round again. In 

 addition to being raised by division, plants may also be 

 raised from seeds, which should be sown singly in small 

 pots and plunged in a hot-bed to germinate, potting them 

 on in the usual way as they fill their pots with roots. 

 Before sowing the seeds, soak them in warm water for 

 several hours, and then nick the outer casing through 

 with a file, for unless this is done old seeds often fail to 

 germinate. The only extra care Cannas need is to keep 

 them out of draughts when growing. They are not 

 much subject to insect pests. 



