20 THE CULTURE OF POT-PLANTS 



if it is used, an outlet — some sort of chimney leading outside 

 — should be provided for it. 



In spite of these precautions, it may happen occasion- 

 ally that some plants will be found in the morning with limp 

 and blackened foliage as the result of having been frozen 

 during the night. In serious cases, where the tissues have 

 been ruptured, it may be necessary to cut away the damaged 

 parts in the hope that the remainder will survive ; but very 

 often the injury is only slight. When freezing takes place, 

 much of the water in the cells passes out into the spaces 

 between them, and it is this loss of water that causes the 

 limpness and blackening. If the water can be restored to 

 the cells, and restored slowly, no great harm will have been 

 done. It is therefore essential that the plants should not 

 be exposed to sunshine. They should be thawed gradually 

 by being placed in the shade. Some authorities recommend 

 that they should also be sprayed with cold — quite cold — 

 water ; but if that is done they should, in order to avoid 

 damp in the greenhouse, be taken outside. In the case of 

 plants, such as Richardias (arum lilies), with large leaves and 

 soft stalks, this is not sufficient. If the stalks (unable to 

 bear the weight of the leaves) kink, they cannot recover. 

 Nothing that can then be done will enable them to stand 

 erect again. To prevent this, the pots should be suspended 

 upside down so that the stalks may hang straight, and, as 

 they thaw, may stiffen in that position. 



Cleanliness is as important in a greenhouse as it is in a 

 room, but in order to avoid damp it is advisable not to have 

 the floor washed in winter more often than is absolutely 

 necessary. When it must be done, a sunny morning should 

 be chosen for the purpose, and the ventilators should be 

 opened. For the same reason water should not be splashed 

 about. When cold weather comes, the rose should be taken 

 off the can and not used again until spring. The water 

 should be poured through the spout on to the soil, not over 

 the foliage. If any plants require cleaning, they should be 

 taken outside on a warm day and syringed there, and be 

 brought back when they are dry. Dirty pots are a common 



