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Chicago Weather Center

Ask Tom why: What is the best time of day to water lawns and gardens?

July 23, 2011

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Dear Tom,

What is the best time of day to water lawns and gardens?

—James Lafler, Chicago

Dear James,

When it comes to watering your lawn and garden, your enemies are sunshine, strong winds, high temperatures and low relative humidity because they increase the rate of evaporation and reduce the amount of water that makes it into the soil. In general, you will find that sprinkling is most effective when the air is calm, temperatures are cool and the relative humidity is high — conditions encountered more often at night, especially toward sunrise, than during the day. Considering the schedules that most urban dwellers adhere to, watering at 5 or 6 a.m. is not likely to be convenient. However, the hours from about 6 to 9 a.m. offer a reasonable alternative — before winds pick up, temperatures rise and the powerful summer sun starts to beat down.