The most favorable temperature for plant growth is generally 70 degrees to 85 degrees. Above that many plants need help to thrive in our yards.
Plants cool themselves by a process called transpiration. They draw water from the ground into their roots. It travels up their stems and into their leaves where specialized cells open to release the water as vapor. It is typically a plant’s first line of defense against heat.
In extreme heat it is largely up to us as gardeners to provide the next line of defense: mulch and water.
Mulch is critically important because it moderates soil temperature and helps soil retain moisture. Two to three inches control weeds which compete for water and take nutrients intended for our preferred plants. Mulch also prevents erosion caused by heavy downpours. It is a workhorse in the garden.