USEFUL GREENHOUSE PLANTS 149 



ing spring, will expand and make a bright display. Get the plants 

 under cover before the autumn frosts. So treated Azaleas may be kept 

 year after year in good condition. In a too dry atmosphere the leaves 

 are liable to an attack of thrips, which can be eradicated in the way 

 previously advised. 



Balsam. See Impatiens. 



Begonia. The Begonias form an extensive class, which may be 

 readily divided up into several distinct sections. First, we have the 

 tuberous-rooted varieties, single and double, which are now so popular 

 both for bedding out and for the greenhouse ; then, there are the dwarf- 

 growing forms of B. semperflorens, which are much used for bedding, 

 and the several distinct kinds, valuable for their winter flowers, and in 

 many cases they do not bloom in winter alone. Lastly, we have the 

 numerous forms of B. Rex, remarkable for their large, handsomely- 

 marked leaves. B. Rex is more delicate than the others, and although 

 the plant will succeed in the greenhouse during the summer it cannot 

 be depended upon to successfully pass the winter in that structure, 

 though if the thermometer does not go below 45 degrees, and the 

 atmosphere is at the time fairly dry, the more robust kinds of this 

 section will, as a rule, be safe. Tuberous-rooted Begonias are generally 

 increased by seeds sown early in the spring, though the particularly 

 choice forms are propagated by cuttings. The seed is very minute, and 

 full directions for sowing it are given in the previous chapter, entitled 

 Seed Sowing. 



Tuberous Begonias, particularly in a young state, prefer a light com- 

 post; hence a mixture of equal parts of loam and leaf -mould with a little 

 sand will suit them well. After the seeds germinate and the young plants 

 are picked off into a pot or pan, the next shift will be into pots three 

 inches in diameter. When they are large enough they should be shifted 

 into pots five inches in diameter, and unless there are a few specimens 

 of exceptionable vigour this size of pot will be sufficient for the first 

 season. Plants raised in this way will, as a rule, flower well during 

 the latter half of the summer, particularly if they have a dose of weak 

 liquid manure every fortnight after the pots get full of roots. In the 

 autumn as the plants go to rest the water supply must be dimin- 

 ished, and the underground tubers will pass the winter in a dry state, 

 provided they are not parched up. A fairly cool spot, where they are 

 quite free from frost, is just the place for wintering tubers of Begonia, 

 such as underneath the stage of the greenhouse, where it is free from 

 drip, or a moderately dry cellar may be utilised for the purpose. Where 

 the Begonias are few in number they may be allowed to remain through- 

 out the winter in the pots they have grown in ; but in the case of a 

 considerable quantity economise the space by turning them out of the 

 pots, freeing the tubers from the old soil, and laying them thickly in a 

 shallow box or pan, then covering them with some dry mould. The 

 size of first season's tubers will vary from that of a farthing to a penny, 

 and when these are grown on the second season they yield the best 

 results. March is a good month to take them from their winter's quar- 

 ters and repot. They should be put into small pots at first, and shifted 



