40 ROCK GARDENING FOR AMATEURS 



giving a free circulation of air to those which are covered 

 by glass. 



Alpines in Frames or Greenhouses require a good deal 

 of care and attention. The great danger here also is that 

 of damp, added to which a stagnant atmosphere is a 

 frequent cause of loss. A free circulation of air con- 

 tinually is very necessary. In favourable weather the 

 ventilators and lights should be wide open. Want of 

 air leads to damping off, and also increases liability to 

 attacks of disease. Where damp has made its appear- 

 ance, a dusting of sulphur may be helpful after the affected 

 parts have been cut off. Stages and floors of houses 

 containing the plants ought to be kept as dry as possible, 

 and excessive watering be avoided. All dead and decaying 

 leaves need also to be removed. Artificial heat in winter 

 should only be applied for the purpose of drying the 

 atmosphere or for bringing into bloom such alpines as 

 are wanted early ; even then the night temperature 

 should not exceed 45 Fahrenheit. If forced prematurely 

 into growth and bloom, alpines become " drawn," weak, 

 and lose their true character. Plants in pots in frames 

 should be plunged in ashes or sand, and looked over 

 frequently, for slugs constantly attack them. 



If a heated house is available, seeds of alpine flowers 

 may be sown there as early as January, but the seedlings 

 must have plenty of air and light from their earliest 

 stages, and it is doubtful if it is wise to sow the seeds 

 before February except in the case of those which are 

 slow of germination. 



