Water and Watering
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Overview:
Water / Watering is something most of us take for granted but don’t necessarily know its importance in gardening terms.
Because their are a number of aspects to water and watering, the writer has chosen to discuss these seperately! (See related links.)
Why do we water?
It is done to replace water that is lost via transpiration from the stomata (pores) on the plant/s leaves.
These stomata open when the plant is turgid* and take in air containing carbon dioxide.
*Swollen or distended with fluid.
When water, carbon dioxide and sunlight react they make sugars, these sugars are the plants energy source, this reaction is known as photosynthesis.
If a plant runs short of water, the stomata close and photosynthesis can stop, leading to slower growth and possibly the failure of flower buds to form and fruit to develop.
During the dryer summer months plants depend on reserves of water in the soil, when this is lacking it must be supplemented by irrigation to keep the stomata open.
This supplementary watering is important for the production of strong, healthy plants, i.e. plants that are watered sparingly but often produce a root system close to the soil surface and these roots soon suffer in dry periods.
The healthiest plants are those that develop a strong, deep root system which is able to tap into more reliable reserves well below ground level.
This then creates the problem of knowing when to water?
When to Water:
Watering in the evening allows the water to drain deep into the soil / compost over night, and early morning watering should be done before the heat of the sun builds up and causes evaporation.
Time of day to water can often be dictated by the life style, and work commitments of the amateur gardener, rather than the needs of the plants, if this is the case then water them when it is most convenient to do so.
If practical, move potted plants into the shade to protect from the sun until they recover.
Throw a sheet of fleece over those pots that can’t be moved.
As a rule-of-thumb, a square metre of vegetation can draw the equivalent of about 25mm (1”) of rainfall from the soil every day.
A couple of signs that indicate conditions are too dry are, leaves begin to droop and / or the soil can feel quite dry when touched.
These two symptoms on their own do not necessarily mean the plant is suffering from lack of moisture,for example;
Sometimes when conditions are exceptionally hot, plants will wilt then recover when the temperature drop, or the first few millimetres of soil may dry out in the sun making it feel dry to touch.
Faced with this inspect the soil deeper down by excavating a hole to one spades depth adjacent to the affected plants, this will give a better indication of conditions at root level, and if watering is required.
Similarly dig a hole one trowels depth when checking containers.