Water and Irrigation

While all plants require water, some are far more drought-tolerant than others. Still, most garden varieties require a regular supply of abundant water. Water takes time to penetrate soil, and if administed as a large amount, even over a few hours, directly to a flat soil surface, most will be lost. Water slowly and thoroughly, not too often, rather than frequently and shallowly.

Soil is important: well-draining soil will allow water to be absorbed effectively, to penetrate down to the roots, as well as allowing oxygen to reach the roots, thus encouraging larger and healthier root systems. Soil rich in organic matter will also retain moisture well, and mulching can help trap moisture further.

Creating a small trough around individual plants forms a simple way of reliably administering water, eliminates runoff and ensures that water soaks down to where it's needed.

A very old but efficient delivery system consists of good-sized clay pots planted into well-dug and compost-rich soil, which are then filled with water. Water slowly oozes through the sides into the adjacent soil, and can provide water for several days to a week. Standard flowerpots work well for pitcher irrigation, but should have the bottom drainage hole sealed off; covering the top of the pot prevents evaporative losses. Note, however, that pots will break in areas of significant frost.

Sprinklers are inefficient: much is lost to wind and evaporation, and the amount reaching different areas varies tremendously. Still, they are inexpensive, can cover large areas, and are quite suitable for lawns, if used in moderation. Note however that over-reliance on sprinklers leads to plants with very shallow root systems, and lawns less healthy and resilient than many that are neglected, and sometimes dry and brown in summer.

Soaker hoses are a marked improvement on sprinklers, and far cheaper than drip irrigation, though less easy to regulate. It's ideal for vegetable beds, borders, anyplace plants are found in rows. Water is readily aborbed, little is wasted. Still, while good on flat ground, soaker hoses do not distribute water evenly on slopes, and algae can build up in the hoses and become a problem especially with untreated well water.

Drip irrigation slowly delivers small amounts of water, at carefully regulated rates, directly to the soil surface, and is efficiently absorbed. Plant yields increase while water losses to evaporation are virtually zero. Better systems compensate for slope, and deliver the same amount of water at each emitter.

A good drip irrigation system consists of shutoff valve, an antisiphon valve and filter, pressure regulator, valves for each drip line, a timer, the hose, emitters (sometimes just holes in the hose) and optionally emitter tubing. Avoid most 'kits' unless these are based on industry-standard parts. These systems are very effective, if expensive, and often not portable.

Requirements of individual species are detailed in the species database.

 
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