I don't know where you live, but here in Virginia it gets hot in the summer. The sweltering weather means...well, plants are thirsty! Sometimes the seasonal thunderstorms and cloud bursts just aren't enough to maintain a green yard.
People in my neighborhood always turn on their sprinklers during the hottest part of day, the early afternoon. Their reasoning? "Well, plants need to cool down too, don't they?"
This strategy not only may harm the plants, but is also extremely wasteful. With such high temperatures, a lot of the water from the sprinkler evaporates away before it can even reach the plant roots. Having a pivot system makes this even worse, because the water droplets have further to go before falling to the ground.
The best time to irrigate is during early morning or early evening, when the sun's rays aren't so strong and overhead. More water actually is able to reach the plants, so therefore you can conserve more water.
An even better idea would be to buy a different type of sprinkler that drips water directly into the ground, eliminating a lot of evaporation. If you don't want to go out and buy it, and you have an old hose, you can also poke little holes on the side of the tubing and lay it out where your plants/grass are. Simple solution for a big change!
This image is courtesy of CmsGardens.
9 Years Later
17 hours ago