In addition to thinking about water conservation when watering the garden, gardeners should also consider the health of their plants. Fortunately, the needs of plant health and water conservation actually coincide, and the same advice about watering holds true for people in drought areas as it does for those with plentiful water who merely want healthy plants. As a general rule, watering should be deep and infrequent, as this helps plants to establish a strong root system. The time of day that gardeners water the garden is also important.
The best time of day to water outside plants is early morning, before the heat of the day has set in. This reduces the amount of water lost through evaporation, and also provides water for the plants to help them get through the heat of the day. Every few days, the garden should be given a deep soaking of water in the early morning, and gardeners should use drip irrigation, watering cans, or targeted hoses, rather than sprinklers and other devices that diffuse the water all over the garden. Sprinklers are inefficient, and they can also cause plant damage. As a rule of thumb, try to water the garden with 1 inch (2.54 cm) of water every week, through a combination of precipitation and watering.
Do not water the garden during the heat of the day, because the water will evaporate rather than penetrating the soil. The goal is to deeply soak the soil, encouraging the plant to put out more roots to search for water, rather than creating a shallow area of moisture and keeping it wet. A plant with ready access to water through daily watering will develop a shallow root system and become weak. Plants that are used to the stress of less frequent watering will also do better in varied weather conditions, or when a gardener forgets to water.
If watering in the evening, after the heat is passed, make sure to water early enough that the leaves of the plants will completely dry before night. Fungal infections can colonize leaves that are left moist overnight, and the roots will also suffer from being watered in the late evening. Being left moist and cold at night can lead to rot and fungal infections.
If you are trying to conserve water, use reclaimed water and rainwater on the garden, and make sure to check your irrigation system for leaks frequently. If you have time, hand-water all of the plants to ensure the most efficient use of water, checking the soil for moisture levels. If you do not, invest in a quality irrigation system that will help your garden to flourish. Gardeners with fewer water concerns should still water wisely, as extra water will not lead to healthier plants.