Water Management in the Garden
Article written by Martin Lee

With all the recent press about the south of England running short of water I thought I had better do my bit for the gardener by explaining how to manage water in the garden. (May 2006). Links are provided to take you to more in depth information contained elsewhere in this site.

Water is made up of two parts of the element Hydrogen ( the word means water maker) and one part of the element Oxygen. It will boil at sea level at 100 Celsius and freezes at 0 degrees Celsius. Did you know that the higher you are from sea level the temperature at which water boils is less. That is why a drink of Tea up Mount Everest will not taste nice.

Garden plants, like most living things need water to survive, although the actually amount of water a plant needs in dependant upon not only it's size but also the family it belongs to. The cacti family and certain fleshy skin have adapted to reduce the amount of water lost.

In order to get nutrients from the ground a plant uses a technique called transpiration, the leaves of many plants are part of this process. Water is allowed to evaporate from the leaves and this in turns draws water up through small tubes from the roots by capillary action, or the wick effect. This process is so effective that 20 more times the amount of water is evaporated from a tropical rain forest than that of the same area of seas or lakes. 

The hydrological cycle or water cycle is the continuous circulation of water between the oceans, atmosphere and soil and rocks. Water in the sea evaporates and then in the atmosphere the vapour begins to cool below it's dew point. The droplets form rain or snow and now take on mass thus fall to the ground. The surplus water forms streams and rivers before finishing back in the sea.

The UK is blessed, in that we receive a high rainfall compared to many countries, however many gardeners allow this to escape before it can be used, therefore requiring additional water from the mains water supply. If we start away from the garden and look at the house we see drainpipes from the roofs that carry precious rainwater away. A diverter arrangement can be fiited to these drain pipes that fill up water butts. One particular water butt made by Harcostar can hold 700 litres (150 imperial gallons). Submersible pumps are now available that can be inserted into the water butt and connected to a hosepipe, saving the need to fill up the watering can.

Many gardeners water the lawn using sprinkler systems or by hand with a watering can (not recommended), however the amount of water that is needed can be reduced by techniques to make the lawn more drought resistant. An autumn lawn feed which is high in phosphates and potash but low in nitrogen, stimulates root growth. Aeration of compacted lawns can also increase the drought resistance.  A top dressing will also increase drought resistance by increasing the moisture retention capabilities by the addition of organic matter. Going back to the watering of lawns, many gardeners when watering the lawn actual make the problem worse, by under watering. Longer grass is more drought resistant; therefore consider raising the cutting height during dry spells.

Containers used for growing plants never seem to be able to cope without additional watering; however the amount of additional watering required can be reduced by mixing water retaining crystals into the compost mix. Avoid unglazed clay pots too since these are porous and allow water to evaporate from the sides. If you have left watering of a container too long then consider dunking into water rather than using normal watering methods. Alternative is to use a wetting agent, LOC from Amway is made from coconuts and is also good as a wetting agent. Use the Google search box to search for wetting agent or Amway LOC. For the top of pots consider using a technique used by the ancient Romans, they used stones around plants to retain moisture. There are many more materials available to us now that can be used to look both decorative and also retain moisture.

Moisture retention of soil can be improved by adding organic material at digging time. Even heavy clay soils will benefit. Water loss can be reduced by using a porous membrane, in addition to controlling weeds. Established gardens will benefit from a thick mulch around plants.

Martin can be contacted at martin@martinlee.co.uk