Commercial Floriculture

Humidity

• • Humidity is very important for the good growth of all plants especially tropical ones and particularly epiphytes, which is much more difficult to control than either heat or light.
• It has been proved that about 50% humidity is suitable for most orchids.
• As a rule, they do not thrive in places where the relative humidity is less than 50%.
• Since they are not regular soil plants, with a proper root system to absorb and supply them with enough moisture from the soil,
• Eepiphytic orchids do best in an atmosphere as saturated with water vapour as possible.
• Excessive humidity is dangerous, as it brings about susceptibility to certain diseases. Plant parts may be attached by various bacteria and fungi.
• Excessive high relative humidity (above 70%) contributes to succulent growth which is more susceptible to infection than hard growth.
• The danger of infection during the high relative humidity maintained for the purpose of cooling the plants in the day time is lessened by good air movement.
• • A humidity level varies greatly from area to area and from country to country and it would be unwise to generalize.
• • The most popularly used device for creating humidity is the evaporative water coolers.
• • Spraying the benches, walls and floor of the orchid house or misting with very fine nozzles are also effective in this respect.
• In stagnant air of a greenhouse, it is wise to reduce humidity at night.
• As a general rule, any form of watering, clamping down or spraying should not be performed in the late afternoon or evening.
• In orchid houses we should run oscillating fans continuously. During the warmer months, an evaporate cooler keeps the orchids house day time temperature around 10 oC and increases further air movement.

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