APRIL, 1915.] THE ORCHID REVIEW. 107 
CALENDAR’ OF OPERATIONS FOR APRIL. 
By W. H. Wuiter, for many years Orchid Grower to the 
K.C.V.0. 
late Sir Vavar Lawrence, Bart., 
HADE AND VENTILATION.—The month of April) with its 
proverbial sudden changes of sunshine and showers, is, without 
doubt, a trying period to all who have the management of a! collection 
of Orchids. On many an April day the changes in the weather are so 
numerous, between sunshine and shade, heat and cold, that it is almost 
impossible to keep the temperatures of the houses regular; although 
shading and ventilation, if carefully attended to, go a great way in averting 
fluctuations inside. East Indian Orchids, particularly Phalznopsis, some 
warm-growing Vandas, Aérides, Saccolabiums, and Calanthes in their 
earlier stages of growth, are, perhaps, more easily affected by varying 
temperatures than those from other parts of the world, as at this season the’ 
majority of the plants are growing fast, and if the growth be checked much’ 
harm to the plants may ensue. On several mornings lately it has been 
found necessary to use, in every division save the Cool house, a consider- 
able amount of fire heat, in order to maintain the proper day temperatures.. 
Even through the middle of the day the pipes have been kept warm, so that 
when the sun becomes suddenly obscured by heavy clouds we can, by 
closing or partially closing the ventilators, avoid any extremé fall in the 
temperatures. Should cold or boisterous weather prevail, it is therefore 
advisable to regulate the temperatures by means of the heating apparatus, 
and on no account to open the ventilators of the warmest house, as 
generally sufficient air will pass through the laps in the glass, and under 
the doors. At other times, when the external air is warm and still, air’ 
should be admitted more freely, opening the bottom ventilators a little at 
first, and as the inside temperature rises gradually increase the amount. 
The blinds will, of course, require a good deal of looking after, but 
there is not the least need to keep working them for every trifling change 
in the weather. Keep them down on all changeable days, and up whenever 
scorching of the foliage is not feared. At this particular time of the year, 
and especially following a dull and extremely wet winter, the foliage of 
Orchids is more apt to get scorched by sunshine than at any other time, 
and it is much the safer plan in every division to err a trifle by giving too 
much shading rather than too little, as more injury is done to the plants 
from too much sun than too much shade. Through the summer, probably 
owing to the abundance of fresh air admitted to the houses, one seldom 
gets an Orchid scorched, while during the ripening days of autumn many 
plants are greatly benefited by all the sunshine they can obtain. In the 
