Irrigation - How To Look After The Watering Needs Of Your Plants In The Winter
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By Jonathan Yaakobi
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A question that troubles many private garden owners in hot dry climates, is the issue of watering the garden plants during the winter. It is a matter that causes considerable confusion particularly to those living in Mediterranean type climates, typified by winters that are generally wet, cool and mild. I live and garden in central Israel, which has an east Mediterranean climate. Some areas like Jerusalem usually receive light frosts during the winter, while on the coast, the temperatures are not likely to drop below 6 or 7c. A common weather pattern is a storm system depositing perhaps some 25-50 mm of rain over a couple of days, followed by a dry spell lasting a week or two, until the arrival of the next system. Warm temperatures around the 18-22c mark often occur in these periods between the storms. Sometimes as in drought years, they can last a lot longer. Whether you live in southern California, central Chile, or south-west Australia and other regions, this pattern will no doubt be familiar to you. The problem is what to do as far as watering is concerned during these dry spells?
There are in fact two aspects that need addressing. First and foremost, we should be interested in saving and not wasting water. Secondly, we should be aware of the needs and requirements of the garden plants. Young plants recently planted, are very likely to need watering during a dry spell, but what about established plants? It is worth knowing that in certain circumstances, not only is it the case that established plants do not require extra irrigation, but the additional watering can actually be damaging to them. So while totally ignoring the matter of irrigation is unrealistic in a Mediterranean winter, leaving the irrigation controller to operate unchecked is not only a waste of water, but liable to result in plant damage as well. How does this happen?
The plants require of course adequate supplies of available moisture to carry out all their physiological functions. Less obvious, although no less critical, is the availability of oxygen in the plants' root zone required to facilitate root respiration. Soil that is permanently saturated with water, is one lacking in oxygen that can be absorbed by the plants' roots. There has to be a balance between moisture and air to allow for healthy growth and development. This is why plants growing in poorly drained soil suffer and are liable to die. During the hot summer months, this is less of a problem due to the high rate at which moisture is removed from the soil both by evaporation and the plants' consumption .However in cool cloudy weather, even if rainless, anaerobic conditions are liable to be created, meaning that insufficient oxygen is available to the roots. Here are some tips for testing whether there is adequate moisture in the soil.
* Look at the herbaceous plants in the ground, whether garden ornamentals or weeds. These can be termed "tell" plants because they tell us to considerable extent the level of moisture in the top soil layers. If the plants look green, vital with the leaves firm and turgid, as opposed to limp and wilting, then self evidently the roots have access to sufficient moisture. Woody plants on the on the hand, should never be used as indicators of soil moisture levels, because signs of stress usually occur after a prolonged period of water deprivation, while herbaceous plants react immediately to a lack of moisture. Signs of stress in a tree can often mean the beginning of the end for that particular specimen.
* The soil surface may look bone dry a few days after a rainfall, but underneath it could be perfectly wet. Scratch the surface with some implement and feel the earth a few centimeters below the surface. If moist and wet, and if the plants look good as described in the previous chapter, then there is no need to water.
* Soil type is a major factor determining the necessity to water or otherwise, at any time in the winter. As clay soils retain moisture to a high degree, they are far more susceptible to prevailing conditions which are lacking in air, than are sandy soils. The latter on the other hand, are more likely to dry out quickly. So in the case of clay, or heavy soil, one should be more wary of over-watering, while with sandy, light soils greater care is needed to ensure the plants are not indeed drying out during a spell of warm, dry weather.
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Author Bio Box: Jonathan Yaakobi
 My name is Jonathan Ya'akobi.
I've been gardening in a professional capacity since 1984.
I am the former head gardener of the Jerusalem Botanical Garden, but now concentrate on building gardens for private home owners.
I also teach horticulture to students on training courses.
I'd love to help you get the very best from your garden,
so you're welcome to visit me on http://www.dryclimategardening.com
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