Of course, it is the hot, dry summers that attract so many visitors to Greece... and make life difficult for the plants. Evapo-transpiration far exceeds rainfall during these months, so the countryside simply dries up in many areas. Some native species go into summer dormancy and any plants that are not adapted to these conditions die, unless given extra water to help them through. In a garden or landscape situation, even Mediterranean and arid­climate plants appreciate a drink, especially during their first three years of establishment. After all, water - along with warmth, light and nutrients - is one of the essential factors for healthy plant development.

The temptation to sustain flagging plants with water, keeping them attractive during a drought, is often too much to resist. However, water is a precious resource in the Mediterranean, to be used with great care. In the last century, new dams, reservoirs and sophisticated distribution systems have made water available on a scale way beyond past imagination. Despite this, demand exceeds supply, as humans consume more and more. Population pressure, rising tourism, drought, depleted wells and aquifers all contribute to a shortage of fresh water. Greece tops the list of European countries in agricultural consumption, while Attica uses more water than any other metropolis on the Continent, according to EU figures.

Not only is the quantity threatened: the quality of groundwater is deteriorating rapidly throughout the Mediterranean. Pollution and salt water intrusion - due to over-exploitation of coastal wells, especially in resort areas - are but two of the problems. The level of salts (particularly chlorides and nitrates) is well above EU standards for human consumption in many places. Plants suffer too. Salt in irrigation water kills, because the strong solution draws liquid from the plant cells, causing desiccation. Similarly it prevents roots taking up water from the soil, so the plant wilts and dies.

Saline levels can be checked, which at least alerts you to problems: however, inexpensive remedies are difficult to come by. Using salt­tolerant plants is probably the most economical and effective option.

Heidi Gildemeister may have coined the phrase "waterwise gardening" in her book Mediterranean Gardening: A Waterwise Approach. She is certainly a pioneer of the careful use of water. During the past 25 years, she has sculpted a distinctive and natural garden out of a maquis landscape, the dense community of evergreen trees and shrubs typical of the Meditenranean Basin. Experimenting with many water-saving techniques, she proves that a considered choice of plants - as well as careful siting, planting and mulching - cuts down on consumption.

On sloping ground, much water is lost to run-off Modify the incline by terracing it. A simpler technique is to create a saucer-like depression, so that the plant sits in a basin (dig deeper to the back of the hole, then mound the excess soil into a ridge around the front). This dams water and catches run-off, allowing the plant to make maximum use of the available moisture.

The rate at which soil is able to absorb water can present a limitation when watering.
The moisture-retaining capacity of almost any soil can be improved by incorporating bulky organic matter, such as well-rotted manure or compost. Mulching is also essential, as it not only minimizes evaporation, but improves rain penetration by preventing the surface turning into a baked crust.

Even with modern computerised systems, it is important never to take irrigation systems for granted. Vigilance is always needed: regularly check that all the plants are receiving the water they require. Power failures, pipe damage and breakdowns can interrupt the system, and, in the worst case scenario, could result in plants dying.

Water should be applied where it is most effective - at the root zone. It is better to water seldom and thoroughly, as opposed to often and shallowly. Small amounts are quickly lost to evaporation. With infrequent deep doses, the water sinks into the soil; the plants then send their roots down in search of the moisture, anchoring into the earth. The deeper the root system, the more effective the plant becomes in water take-up. Conversely, frequent shallow watering encourages roots in the top 5-IOcm of soil, making the plants more susceptible to drought. Watering deeply once a week during summer is sufficient for most established plants of Mediterranean origin. Non­native and exotic specimens may need more help.

Pots and lawns are more difficult to manage in this way. Grass swathes need frequent watering to keep them looking good (a reason to reconsider their use in the Mediterranean). Because their roots develop near the surface they are vulnerable to drought. Containers also tend to dry out quickly and demand daily watering during the summer. With terracotta, always douse the pot as well, so that the clay doesn't suck moisture from the soil.

Early morning is the optimum time to water, because it ensures that moisture is present during the hours of photosynthesis. Watering in the late evening or at night is almost as effective as there is relatively little moisture lost from the soil then. Ideally, avoid watering in the middle of the day. The drops of cold water on hot leaves can concentrate the sun's rays to such intensity that the foliage scorches. Of course, much more liquid is lost to evaporation when the ground and air are at their hottest and driest. Also considerable damage can be done by suddenly changing the temperature of the plant, which watering on a hot day does.

The amount of water needed depends on the soil, the situation (sheltered or exposed)
and the type of plant. Observation is the key. However, it is actually quite difficult to give a plant too much water in summer and too little water in winter, especially in open ground. Nevertheless, try to arrange plants according to their water needs, making irrigation easier. Thirsty species are best grouped near the house, so that you can keep a close eye on them and tend to them as necessary.

How much potted plants require is dependent on season, the species and the type of compost used: for example, peat-based blends are light but absorb many times their weight in water. With time you can gauge by pot weight how quickly the plant uses the moisture, how much water to give and how often. A saucer underneath the container acts as a guide - if there is water in the dish, the plant does not need more liquid (remove it in the rainy season, though. Roots rot if left sitting in a waterlogged substrate). However, the simplest way to check moisture is to stick your finger in the soil ­you'll soon tell if the plant needs water.

Gardeners in the cooler climes of England may not have the watering worries of Greece . .. nor do they have the possibility of sitting on the terrace at midnight without shivering. It really pays to organise efficient watering and look after the soil if you plan to enjoy a Mediterranean summer in your garden.