“light” has a big bearing on the difficulty which we find in flowering certain 
Orchids. 
Whether a plant is a long-day or a short-day plant depends almost entirely 
upon the physical conditions of its native habitat. Thus of two plants growing 
naturally on the same parallel of latitude one may be a short-day plant and the 
other a long-day plant, because the first may grow in a deep gulch into which the 
sunlight may penetrate only for an hour or two each day, while the other may 
live high on a tree, or a cliff, exposed to the sun’s rays for many hours each day. 
It is desirable, therefore, that we ascertain as nearly as we can, how each of our 
Orchids grow, naturally, particularly in the case of species. Thus, if we know 
that Vanda suavis grows in Java on trees in the shade of other trees, and that 
Vanda tricolor also grows in Java, but grows upon stunted trees which allow 
the full light of the sun to play upon it for the greater part of the day, it will 
require no great amount of intelligence to decide that Vanda suavis must be grown 
in a somewhat more shaded position than Vanda tricolor. But if we are having 
difficulty in flowering either or both tricolor and suavis, it may puzzle us to know 
the reason. Assuming that our attention to temperature, moisture and nutrition 
has been in accordance with the known requirements of the plants, we will be 
justified in looking into the matter of the lighting conditions in which they grow. 
Java, of course, lies in the equatorial zone, and hence has days which are 
divided practically equally into darkness and light all the year round. Here in 
Brisbane we are right outside the tropics and, therefore, our days are considerably 
longer in summer time than in the winter. The winter period is the time when 
these Vandas ate getting ready for their spring and summer flowering. From 
their manner of growing on trees in the tropical belt, we know that they are 
both probably “long-day” plants, and that in their natural haunts, under the 
influence of the warm long tropical sunlight, their chemical functions are work- 
ing at high pressure right through the winter. Therefore, it will probably assist 
the plants to flower in the next spring if we move them so that they get the maxi- 
mum amount of sunlight during the winter months—always remembering that 
suavis can do with a little less sunlight than ¢ricolor. I have chosen these two 
Vandas for this example because, as a general rule, they are very easy to flower in 
Brisbane, our climatic conditions meeting their requirements reasonably well— 
and yet from time to time we hear growers say: “I can’t flower suwavis,” or “my 
tricolors never do as well as so-and-so’s,” and so on. The failure is most prob- 
ably due to a deficiency of light during the winter period. 
Cattleya Warscewiczii or, as it is usually called, gigas, is notoriously hard to 
flower. This Cattleya grows high up on the Andes, principally in the Republic of 
Colombia which, again, is right in the centre of the equatorial belt. Here it 
grows upon the sparsely-leaved trees, and even on the high, almost inaccessible 
cliffs nearly 8,000 feet above sea level, where it is exposed to the four winds of 
heaven, and to the full force of the tropical sun. Under these conditions it 
flowers regularly and abundantly every spring. Yet, transferred to our sub- 
tropical climate, and given all the refinements of Orchid culture, it often refuses 
to show a sheath, although it grows rapidly. I am confident that this is largely 
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