Once established, woody plants generally need little supplemental watering - providing they have been given a proper start. The first critical watering comes immediately after planting, when you should water in new specimens deeply and thoroughly. The purpose of this is not only to provide plants with the moisture they need but also to dispel air pockets and help soil make good contact with the roots.

Thereafter you need to monitor all trees and shrubs carefully during their first three years fir signs of water stress, such as drooping or wilted foliage or poor flower productions. Most woody plants need about 1 in. (2.5 CM) of water per week and should be watched particularly closely during periods of drought, extreme heat, or high winds.

Whenever you water, be sure to soak the soil sufficiently, so that water reaches the full depth and spread of the root zone. Deep watering encourages deep roots, which are better able to seek out moisture from the soil. In sandy soil, water will penetrate but also dry out quickly and may need to be replenished more frequently; the opposite is true of clay soil.

The Battle Against Water Shortage
The battle against water shortage should begin before the days of summer. Add organic matter to the soil before planting, water in thoroughly after planting and mulch the plant in spring every year. For the first couple of years of a shrub's life in your garden, copious watering will be necessary during a prolonged dry spell in late spring or summer. Once established the plant will need watering much less often.

The need to water, however, cannot be ignored. If the weather is dry, look at the trouble spots. Climbers growing next to the house, shrubs in tubs and all plants growing in very sandy soil will probably need watering. Then there are the shallow-rooted plants which can quite quickly suffer even in good soil once the dry spells of summer arrive. Rhododendron is a well-known example of a shrub which quickly suffers in drought, but there are others.

Once you decide to water, then water thoroughly - a light sprinkling can do more harm than good. As a rough guide use 1 gallon for each small shrub and 4 gallons for each large one. A watering can is often used, but a hose-pipe is a much better idea unless your garden is very small. Remember to water slowly close to the base of the plant. Trickle irrigation through a perforated hose laid close to the bushes is perhaps the best method of watering. A quick and easy technique popular in America is to build a ridge of soil around each bush and then filling the basin with a hose.

The Best Watering Methods
Watering large areas with a hand-held, high pressure hose is a waste of time because so much of the water runs off instead of sinking into the soil. Moving hoses and sprinklers from place to place is tedious work as well. For the best results with the least effort, consider a system of low pressure hoses and delivery devices that is custom tailored to your site. These systems can be installed above ground or buried and not all of them require installation by a professional. Some can be easily put together by the homeowner from materials available in the local garden center and can be ready to operate in just a few hours.

First off, there are two basic ways to apply water to your garden: by sprinkling or by soaking. Sprinkling works well with perennials and ground covers, especially those that thrive in a humid environment. The overhead action helps wash dust and pollutants from foliage, and it also discourages undesirable insects such as spider mites. Roses and bulbs - plants that are prone to fungus diseases - will benefit most from watering with a soaker hose, which supplies a slow, steady flow of water directly into the soil. Soaker hoses are also preferable for areas prone to summer drought and for those flower beds to narrow to be sprinkled without a lot of waste.