During these massive heat waves, don't let your flowers wilt and die. Use a patio umbrella to protect them. My spider lilies were wilted and dying from 103 degree F heat. I gave them some extra water and used a patio umbrella to protect them and it brought them back to their beauty.
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In an intense heat wave, I have saved my garden produce from sunburn and kept the plants green by covering them with old bedsheets.
According to climatologists at the U.S. National Weather Service, a heat wave is defined as three consecutive days with a minimum shade temperature of 90ºF). For those of us in the Northern Hemisphere, that's a pretty good description of at least part of our summer.