You can wait much longer during the winter or when watering soils of finer texture, such as muck or clay. Many landscape plants demonstrate their need for water by wilting. If they continue to wilt during the evening, water them the following morning. Some herbaceous plants, such as impatiens and coleus, typically wilt during the heat of the day, even though the soil contains adequate moisture. There is no need to water these plants unless they remain wilted during the evening.
Some plants show no early symptoms of drought stress.
Plants should be watered before the appearance of injury symptoms, since at this stage of drought stress they may become severely damaged or even die. Plants in sandy soils exposed to full sunlight may need water every three to five days. The same plants placed in some shade or in soils of finer texture may need water only once a week, perhaps less often. Monitor the lawn closely. If it shows signs of wilting, it needs attention.