OCTOBER, 1915.] THE ORCHID REVIEW. 209 
CALENDAR OF OPERATIONS FOR OCTOBER. 
) 
By W. H. WHITE, for many years Orchid Grower to the 
late Sir Trevor Lawrence, Bart., K.C.V.O. 
EMPERATURES, &c.—At this time of year it is important for the 
Orchid grower who is in charge of the heating apparatus to keep a 
sharp look-out for sudden falls in the temperature of the external air, so 
that all evil effects to the plants from this cause may be avoided. It is no- 
uncommon occurrence during October for moderately sharp morning frosts. 
to make a sudden appearance, and consequently without the slightest 
warning. In such cases the temperature of the various divisions may fall 
a few degrees below their proper standard, unless the man in charge of 
the fires the previous evening had been sufficiently weatherwise to foresee 
what was coming. On such occasions, when the temperatures are 
low, no watering or damping down should be proceeded with before the 
proper degree of warmth is reached, as the drier the houses are under such: 
circumstances the better, and the less likelihood will there be of serious- 
injury to the plants. The temperature’ of the East Indian, or warmest 
house, at night, should be about 70°, that of the Cattleya house about 65°,. 
and the Mexican or Intermediate house a few degrees less. The Odonto- 
glossum house should be about 55° or 57° at night, and about 50° or 54° in 
the morning. When banking up the fires the last thing at night the one in 
charge of the heating apparatus should so manipulate the dampers that 
there may be a fall of several degrees in each division by the early morning. 
hours. 
During the month of October, following so closely, as it so often does,. 
upon warm summer weather, it is advisable in every department to err a 
trifle on the warm side with the night temperatures, as one sudden fall of 
several degrees, especially if the plants have been very recently watered, 
and the atmosphere has been unduly moist, might do more harm to many 
tender-growing plants than all the cold of winter. Even if the Cool house 
through the night is a few degrees above the normal temperature, no harm: 
will accrue, provided the ventilators on all suitable occasions are freely 
used, and the little extra fire heat, and increased ventilation, will often 
prevent the unsightly dark fungoid growth so frequently seen on the under- 
sides of the foliage of Odontoglossum crispum, and its allied species and 
varieties. It is advisable to see that none of the plants are too near the 
roof glass, as that is a frequent cause of their being chilled. Thoroughly 
cleanse the plants of all insect pests before winter sets i, both by sponging — 
and by vapourising each house every week or two with some safe and 
effective insecticide. 
OpontTocLossuM HOUSE.—Look carefully over the newly-potted plants 
