Caring for Orchids – Humidity
Caring for Orchids – Humidity
Humidity levels of 60-70% are the ideal conditions in which orchids will feel really comfortable.
During the summer, lack of humid air is not a great problem. In fine weather the humidity levels indoors will be about 50%; during dull, rainy weather 60-80%. Outside, in well-ventilated summer quarters, especially during thundery weather, conditions may be even better still. The critical time is during the winter, when the warmth from central heating systems eats away at the humidity levels in the air. In addition, in most homes the central heating radiators are situated right underneath windowsills. This means that the humidity level may rapidly drop to below 40% which is much too low for orchids (and even for most other indoor plants).
Humidity or “relative humidity” is defined by the percentage of water vapour molecules in the air. 0% = absolutely dry, 100% = saturated water vapour mist.
How to measure humidity
A gadget called a hygrometer is used to measure humidity levels. It can be part of an entire home “weather station”, together with a thermometer and a barometer, or you can buy the individual pieces of equipment. These items make it possible for orchid growers to monitor humidity levels. You can observe how these levels constantly change. If the level drops below 60%, it will become necessary to take action.
How to raise humidity levels
The best tried and tested gadgets for raising humidity levels are misters, electrical humidifiers, a plastic grid or a specially equipped plant container.
A mister bottle or spray attachment:
These will supply sufficient humidity for everyday use. Adjust the mister outlet to its finest setting and spray only the leaves, not the flower! Just as when watering, it is better to spray the leaves in the mornings. The plant will then have plenty of time during the day to dry off before the temperature drops again at night.
Do not spray any plants while the sun is shining on them! The minute droplets of water will act like magnifying glasses in sunlight and may cause burns on the leaves.
An electric humidifier: will supply a constant rate of humidity during the central-heating season indoors. This can be obtained from electrical suppliers or orchid suppliers.
A plastic grid:
All that you need is a rectangular dish and a grid insert, both made of plastic. This dish, which can accommodate several orchids at once, will have a constant supply of water in it so that the plants always have dry feet but will be permanently surrounded by evaporating water and thus enjoy plenty of humidity.
A plant bath: is filled with Hortag or peat. This substance should be kept permanently moist so that it can release water vapour into the air.
Further tricks for increasing humidity:
- Stand bowls of water between your orchid pots.
- Place dishes of permanently moist Hortag, sand or gravel under upside-down pot-holders with orchid pots standing on top of them.
- Use larger pot-holders with the spaces between the pot and pot-holder filled with Hortag or peat that is kept constantly moist. This method will only work properly with orchids in clay pots!
- Use waterfalls, indoor fountains, a spring stone surrounded with plants or aquariums.
- Supply large-leafed, neighbouring plants which evaporate plenty of water, for example Araceae, Maranta or bromeliads.
- Use marginal plants which stand permanently in water, like Cyperus.
Use distilled water for misting or spraying (obtainable in chemists, etc.). This will prevent chalky deposits on window panes. Water in evaporation dishes, which does not come into direct contact with the plants, need not be softened. If chalk deposits appear on the insides of dishes, they can be removed with diluted vinegar.
Fresh air — but no draughts!
Regular airing or ventilation is extremely important for the wellbeing of orchids — in particular for their aerial roots! Fresh air will prevent decay and the proliferation of fungi and pests. There are many ways to supply extra oxygen:
- by opening or tilting the window
- by installing a sliding ventilation hatch or tip-hatch
- by means of a ventilator on the inside of the window
- by means of electrical ventilation
- by allowing the plant to live outside during the summer months.
If you air the room in the winter, you should cover up the plants beforehand or move them from the windowsill. Cold draughts are lethal for them.
Avoid the scent of apples!
In contrast to bromeliads, whose flowering is triggered by the odour of apples, orchids react with falling buds or flowers. The cause is the ethylene gas released by apples, so never stand a fruit bowl close to your orchids!