The same is true with orchids. They must be given these five factors in certain definite proportions which are, however, considerably different from those most other plants receive.

Rule No. 1

Provide orchids with usually not less than 40 per cent and usually not more than 70 per cent atmospheric moisture (relative humidity) during the day.

While most plants get along on a definitely predetermined modicum of growth factors, several have eccentricities which should be pampered a bit. The eccentricity of orchids is that they require more atmospheric moisture than many other plants. Orchids are dependent on humidity owing to their strange, evolutionary adaptation to their native climate

Rule No. 2

Orchids must have an abundance of fresh air at all times.

In outdoor gardening there is little to worry about if the air moves easily around the plants and is kept moist on warm days by evaporation from soil or other suitable material that is occasionally wet down. Usually, orchids grown outdoors for summer culture are set above the ground on inverted pots in order to insure the best air circulation and the most efficient use of air moisture. If drainage is excellent, potted terrestrials may be sunk into the ground.

Indoors, plant and human requirements for ventilation are essentially similar. A house that is healthy for humans is equally healthy for plants. If you possess a modern air conditioning unit that continuously circulates moist warm or cool air, depending on the season, the problem of ventilation is solved.

Rule No. 3

Orchids must have the maximum amount of sunlight they can stand without injury.

Since the effect of light on orchids is still largely experimental, it is wiser to try out all orchid plants. Give them a reasonably large and continuous amount of light - the light that passes through sleazy muslin is good for a start. Then gradually transfer them to shadier places until the correct light intensity is reached.

Rule No. 4

Orchids require protection only from frost and snow.

This does not mean that warmth is not necessary to all orchids, nor does it preclude the use of artificial heat in rigorous climates. It implies that man-made heat cannot compete beneficially with nature stimulating warmth. Artificial heat is a temporizing and last resort.

Rule No. 5

Orchids must be fed. They must have a sufficient supply of continuously available mineral nutrients.

The symptoms of malnutrition in orchids are not yet completely understood. These symptoms seem to follow the same general pattern in orchids as in other garden plants. A lack of nitrogen stunts growth and causes leaves to become yellow at the tip. Excess nitrogen produces rapid, soft, and flabby growth.

These are the fundamentals of orchid culture - humidity, air, light, protection, and food. The corollaries of composting and watering depend upon them and are manual processes which may be suited to your convenience. But don't try to change the rules governing the basic needs of orchids. Orchids are tolerant, but they have certain minimum growth requirements which must always be taken into account.