Late evening is probably the worst time to water, as it leaves the foliage damp at night when molds and fungi are most active. But never let a bone-dry garden go without watering simply because you can't do it at the optimum time of day. Automating Your Watering Irrigation systems can be great time savers for those with large gardens or little time. The best use drip hoses to supply water directly to the base of the plants. This minimizes the loss of water to evaporation that makes sprinkler systems so inefficient, particularly in hot, dry climates.
Sprinkler systems are also much more prone to mechanical failure.
And since they are usually set to go off in very early morning, problems can be difficult to detect. Place the hoses under any mulch and about six inches from the base of your plants. With just a minimum amount of pressure, this hose can be left on for several hours. Keep an eye on your garden's moisture and you'll save yourself much trouble and expense.