Water is essential if your indoor plant displays are to survive for more than a week or two.  This part of the Plant Requirements module explains how much water is needed under different circumstances, how that water can be provided to the plants and the provisions that need to be made to ensure that water is available and can be given to the plants safely and with as little impact on the environment as possible.

Principles

Indoor plants need just enough water to maintain their physiological wellbeing, but no more.  Water is taken into the plant by its roots, highly specialized organs that regulate the uptake of water and nutrients as well as providing anchorage and physical support.  Unless the plant is an epiphyte (a specialized group of plants that live among the tree tops, e.g. bromeliads and many orchids) or a water plant, the roots of a plant are buried in the soil.  This is where the water needs to be.

Plant roots are covered with tiny hairs.  These increase the surface area of the roots considerably and these are the places that water is taken into the plant.  The root hairs need oxygen to work properly, so a supply of air is also necessary.  That is why compost media with large numbers of air-filled pores are essential and why water-logged soils cause plants to die.

Properly watered plant	Over-watered plant