HUMIDITY: Measurements and Accuracy

Culture Orchid Doctor

by Robert M. [Bert] Hamilton (Compiler)

Originally published in The Orchid Doctor in 1980 and 1988

Posted by Sys Admin almost 8 years ago.

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The often inaccurate needle-and-dial hygrometer can be calibrated in a jar using common chemical saturated solutions of known % relative humidity at 25 dC. A80-1382
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Humidity Comments
HUMIDITY: Additional Amount Applied to Cattleyas Do not use a tank-like enclosure; partially enclose the plant; if leaves are firm use a tray with pebbles and place the plant on it; if the room is dry add a humidifier. A70-235 0
HUMIDITY: Altitude Difference At sea level, which is where the phalaenopsis mostly grow, 100% relative humidity means a lot more water vapour per unit volume of air than at an altitude higher up, so there is a vast difference between 100% at sea level and 100% at 10,000 feet where the masdevallias thrive. OR82-27; A81-793 0
HUMIDITY: For Cattleyas Set the humidifier at 70% relative humidity if the humidistat is reliable, and sensitive; set at 60% to 70% on one that is not. A65-438; phalaenopsis and cattleyas. A80-630 0
HUMIDITY: How to Lower It An air conditioner is needed, but plants prefer high humidity, with good air movement and with fans acting against condensation, which might favor the development of disease A67-139 0
HUMIDITY: Maintaining it The relative ineffectiveness of "damping down" compared with using misters; at 5,000 feet altitude or more the amount of water carried by the air can be about one-third reduced; to maintain it in the greenhouse various devices are available, such as a time-switch, a micronic timer, a solenoid valve, atomising water-jets, etc., refer to OR87-120 0
HUMIDITY: Maintaining it with a "gadget" A canvas soaker hose fastened to the top row of the finned heating pipes and with a slight flow of water leaking from it raised the humidity of a test area from 20% to 60%. A59-514 0
HUMIDITY: New System Install a fan on the floor pointing upwards, with overhead water sprays not directed onto the- plants, so that humidity is increased to about 907o relative; this produces increased growth and no losses; refer to A85-960 0
HUMIDITY: Providing it Automatically One system uses three mist sprays per nine feet of length on each side of the greenhouse, activated by means of a solenoid valve controlled by a humidistat sensor; the standard hook-up. OR85-418 0

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