NEW ZEALAND GARDENING. 177 



Air in Greenhouses. The circulation of air is one 

 of the most important provisions in all kinds of horticultural 

 buildings. Nothing but that will fairly exclude damp, or in 

 any damp weather counteract its effects. It is not enough 

 to open every front window. It would be far better to open 

 only one and let down a top light a little. In all cases there 

 should be an outlet as well as an inlet, and for the want of 

 this many houses do not answer well for plants. A circu- 

 lation of air causes a more rapid evaporation, and it is a 

 common thing among good gardeners to open a lower 

 window even in wet, cloudy weather, let down one of the 

 top lights a little, and light a fire. By this a free circulation 

 is created and the house dried, although it were in the midst 

 of rains and cloudy weather. It is too common a thing to 

 see the top lights let down to give air to a house and no 

 other part opened. This is all wrong ; for there should be 

 a draught. On the other hand, we see all the front windows 

 and no top lights down. Many persons build pits three or 

 four feet high at the back and half the height in the front, 

 and no air but what can be obtained at the top. We would 

 always provide air holes at the bottom, as without such 

 there can be no draught, no free circulation. When pits are 

 built without this provision the best mode of giving air is to 

 pull up one light to let in air at the foot of it, and push 

 down the next to open at the top, and so on alternately through 

 the whole range of lights, however long the pit may be. It 

 is the same in giving air to a hotbed ; only that when the air 

 is rarefied, as it is inside, tilting the light a little lets out the 

 steam, and the cool air will get in somewhere ; but sometimes 

 when a frame is made too close and the glass is puttied at 

 the joints, things damp off in spite of tilting, because there is 

 no circulation. , 



Potted Plants. All plants in pots, when exposed to 

 the sun and wind, require frequent watering, and simply 

 because the pots dry fast, when the fibres of the plants 

 surfer directly. This would seem to demand that when pots 

 are in the open air they should be plunged ; but there is 

 another mischief that awaits them if this be done worms 

 get into the pots, and the roots get out of the pots, and, 

 striking into the earth, excite a growth which is not desirable 

 while there, and receive an awful check when the pot is 



N 



