SHADING
It should be distinctly understood that every Orchid house needs to be fitted with proper means of shading, extending over the whole roof and removable when necessary. Some cultivators think they meet the case by providing shading only on the sunny side, or by painting the glass with some kind of preparation more or less in the nature of whitewash. Such preparations should never be used, because, when this is once placed on the glass, the shade, such as it is, is there in dull as well as bright weather, in the night time as well as the day, and for the greater part of the time, especially in dull seasons, it obstructs light which is necessary for the proper development of the plants. Another important objection to their use is that shading given by these washes wears off and leaves the plants exposed to the full sunlight. The substance is washed off by the rains and carried into the rain-water tanks, thus causing injuries to the plants watered with the polluted water, and rendering unsightly the foliage moistened with it.
Proper blinds running on iron or wooden supports, raising them well above the glass of the roof, are absolutely necessary. Lath roller blinds are excellent for shading, being durable, clean, and easily let down and drawn up.
Light canvas or scrim shading fixed to roller blinds answers the purpose well, but care should be taken not to employ heavy, closely woven canvas. Too great attention cannot be paid to the working of these blinds, for they must never be down except when required for protection against the sun's rays, and they must be drawn up during dull intervals.
The blinds are useful also during severe winters as a protection against excessive cold at nights, and in this particular the lath roller blinds are the best, and may be left in position where they are likely to be required for this purpose.
When canvas blinds are used during the summer and removed in late autumn, care should be taken to have them perfectly dry before they are stored for the winter in some dry place, or they will be useless when they are required for placing in position the following spring.