Quantity of water in the atmosphere. Use this tag with questions about the effect of different humidity levels on plants, landscape elements, insects and pests or how to create an environment with certain humidity levels.

refers the amount of water (moisture) in the air as water vapour.

The quantity of moisture per unit volume, that air can contain; varies greatly according to air temperature. Therefore humidity is usually measured as Relative Humidity. This is a percentage of the maximum amount of water that the air can currently contain. Ie. 0% is completely dry (no moisture present), however 100% is the maximum amount that the air can contain (any more, and the moisture will form a precipitate - eg. rain).

The Earth has environments which range from virtually 0% (eg. the Atacama Desert) through to humidity at or near 100% (tropical rainforests). Plants have evolved to live in all of these conditions. For example rainforest plants can survive high moisture conditions, whilst cacti have evolved to solve in low humidity conditions.

Humidity is just one of the environmental conditions that has to be satisfied for your plants to grow well. Use this tag for all questions about humidity. It should be used with tag(s) specific to the plants or plant groups that you are asking about.