Gardening Through the Heat

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Much of the state (county, country, and world) are experiencing long periods of extreme heat. This is a challenge for all living beings, including plants. One day of extreme temperatures can be a problem, but when it continues for a week or more, plants really suffer. Here are a few tips that may help your plants survive, though the longer the heatwave, the more stressed they will become.

Tips

Before extreme heat arrives

  • Water deeply during the cool part of the day to hydrate plants.
  • Spray leaves in early morning to remove pests and dust. The leaves will dry off quickly as the day proceeds, reducing the chance of excessive fungal and bacterial growth.
  • Trim young, tender growth if you think the plant will have trouble maintaining hydration.

It is so hot out there!

  • Shield young plants with screen, shade cloth, or white sheet.
  • If your plant is stressed, check the soil to make sure it is dry and then water deeply. If soil is moist, more water will not help. Most plants shut down during extreme heat, so if it is over 100 degrees, it may be best to wait to water even if your plant is stressed. Throw a damp sheet over it, or mist it lightly to bring the temperature down.
  • Mist leaves with a spray nozzle to cool down plant and reduce transpiration.
  • Desert plants can be watered in the late afternoon to mimic the summer monsoonal rains that they are adapted to.

Post Apocalypse

  • Once it has cooled down, water plants deeply.
  • Do not remove wilted leaves just yet. They will serve as sun shield if another heat wave is on the way.
  • If plants that exhibit summer dormancy have lost most or all of their leaves, allow them to continue into dormancy by not watering. Extra water now could pull them out of dormancy. These stressed plants may then expend a lot of energy growing a new set of leaves only to be faced with the likelihood of more heat and no natural rainfall. Furthermore, our native plants are adapted to a dry, hot climate, and therefore, are susceptible to fungal pathogens that grow in moist, warm soils.

Real Life Examples

I took the following pictures at the South Pasadena Nature Park during a heatwave in July of 2018. Fortunately most of these trees and plants survived. The last picture shows my orange tree with a damp sheet thrown over it. We obviously couldn’t do this for our large old avocado. It experienced a lot of leaf scorch but survived as well. Click here for earlier posts on how to help your plants survive extreme heat.

Leaf scorch on western sycamore, July 2018
Leaf scorch on western sycamore, July 2018
Leaf scorch on coast live oaks in the South Pasadena Nature Park.
Leaf scorch on coast live oaks in the South Pasadena Nature Park, July 2018
Damp sheet thrown over a small orange tree may have helped reduce leaf scorch
Damp sheet thrown over a small orange tree may have helped reduce leaf scorch, June 27, 2022

Please comment with your own tips and suggestions. If you disagree with mine, let me know how and why so we can learn together.

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