GREENHOUSE AND CONSERVATORY 287 



vitality well, and if crowded together the seedlings quickly become 

 weakened, and never attain the vigour of those that are allowed ample 

 space from birth. After sowing cover the seeds by a sprinkling of 

 soil that has been passed through a sieve with a quarter of an inch mesh. 

 The depth of the covering depends greatly upon the size of the seeds, a 

 good general guide being to bury the seed at its own depth below the 

 surface of the soil. This in the case of minute seeds means merely a 

 slight sprinkling. Some seeds, such as those of Acacias and Cannas, are 

 very hard, and frequently take a long time to germinate if sown in the 

 ordinary way. To assist germination the seeds are sometimes filed, 

 but there is some risk in this, a more satisfactory plan being to soak 

 hard seeds for twenty-four hours in warm water. It should be kept if 

 possible at a temperature of 80 degrees to 85 degrees. This treatment 

 will have a considerable effect on the seed, which must be sown directly 

 it is taken from the water. The soil must not get too dry after sowing 

 as the seeds will be just on the point of starting into growth, and in this 

 stage are soon injured by drought. 



In the case of very tiny seeds such as Begonia, Gloxinia, Lobelia, 

 and others a different course of treatment is needed. After sowing the 

 seed thinly on the moistened surface of the soil, which has been watered 

 through a fine rose just beforehand, the only covering needed will be a 

 pane of glass laid over the top. This should be allowed to remain until 

 the seeds germinate. When this is done the sun must not shine on the 

 glass, otherwise the small space between it and the surface of the soil 

 will be so hot as to roast the tender seedlings. As soon as they have 

 formed the cotyledons, or seed-leaves, remove the glass and inure the 

 young plants to the ordinary atmosphere of the greenhouse. With 

 regard to the length of time occupied by seeds before they germinate no 

 hard-and-fast line can be given, as some remain much longer in the 

 ground than others ; while much also depends upon the seed itself, for 

 if kept a long time before sowing its germination is, as a rule, more 

 irregular than if sown soon after it is ripe. Thus Primula seed will 

 often germinate in a fortnight or so after sowing, but it may remain for 

 a year and finally grow. 



The seeds of all that section of plants known as dicotyledons, which 

 include most subjects grown for the greenhouse, first push above the 

 surface a pair of cotyledons, or seed-leaves, as they are often called. 

 Then from the centre of these appears the first proper leaf, and as the 

 plants develop the cotyledons finally die away. A critical time with 

 many seedlings is just as the first true leaf develops, the young plants 

 being apt to topple over and decay. This kind of decay is known as 

 " damping off," and is frequently due to an excess of moisture or too 

 close an atmosphere, but however carefully seedlings are looked after it 

 is very liable to happen, especially if crowded. To stop this damping 

 off transfer the young seedlings to other pots or pans, using a pointed 

 piece of wood known as a dibble in the case of small kinds. 



Pricking off the Seedlings. The process referred to in horticultural 

 publications as " pricking off " is carried out in the following manner : 



