Irrigate your plants deeply if extremely hot weather is predicted. Watering the plants ensures their roots have plenty of water. Even though morning watering is normally the best practice, water the night before predicted heat if you will not be able to water the morning of the day hot weather arrives.
Water established plants deeply once or twice each week. Gauge whether or not you watered plants deeply by measuring the depth of moist soil after watering; moist soil should reach about 1 inch deep.
Provide water to plants near your lawn more frequently than you water other plants. Plants near lawn become accustomed to irrigation a lawn receives and may have more shallow roots than plants farther away.
Water plants in morning so more water will go into the soil rather than evaporate in the hot air. Morning watering also allows leaves, stems and flowers to dry out quickly, making them less susceptible to fungal growth.
Irrigate slowly to decrease runoff and to allow the water to soak into the soil. Deep watering encourages deep root systems that will protect your plants against drought and hot weather. Consider installing a soaker hose or drip-irrigation system instead of watering with an overhead sprinkler or with a hose.
Examine your plants' leaves during extremely hot weather. Leaves that wilt during the day but appear fine the next morning receive enough water. If the leaves still droop the next morning, however, then the plants are either overwatered or need water.
Feel the soil around your plants if their leaves droop the morning after you water the plants. If the soil is still moist, you overwatered and need to let the plants recover and dry out. If the soil is dry, then water the plants again, even if you just watered them the previous day.
Spray the leaves of your plants with an antidesiccant product if you are unable to keep up with watering them. Antidesiccants slow the rate at which plants lose water and protect them during long periods of drought. The best time to apply the spray is when you are not able to water the plants right away.