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Prepare our Landscapes to Survive Weather Extremes

The past few months' weather conditions have reminded us of the importance and benefits of Sustainable Landscape Management® practices.  Now that the temperatures are at least ten degrees lower and humidity has increased, we are seeing many plants and trees responding with new growth.  If these summer conditions continue every year, the best way to prevent plant stress is to prepare before they arrive.

• Irrigation – Plants and trees with different water demands should be on different zones; trees need a much deeper, longer watering runtime than cactus and shrubs. All properties should have pre-summer irrigation audits to check emitters and valves to ensure they work properly before the summer heat.  The only accurate way to check that your plants are receiving adequate water is to probe the soil and adjust so the root zone within the drip line receives sufficient and proper hydration for the plant or tree's age, size, and species.
• Monitor and Adjust – With the cooler temperatures and monsoon activity, it is just as crucial to reduce water as needed.  Many shrubs and trees now have dead or burned leaves that are not taking up the same amount of water as before; if the ground is saturated with too much water, the plant can’t breathe, increasing disease susceptibility.  Taper water with temperature reductions, but be prepared to increase if hot and dry weeks return in the late summer.
• Appropriate Plant and Tree Species – When designing your project, use native or desert-adapted species that can withstand intense conditions.  Take note of the thriving plants and trees on your projects that appear to have little adverse effects from the heat.  Also, note different locations and how the plants respond; some plants won’t survive the reflective heat of the pavement, structure, or window, no matter how much water you give them.  Get to know your plants and the plants used on your projects.  We use many species that have adapted to survive the summer by going through a dormancy period.  Our responsibility is to educate ourselves and our clients that these plants are not dead and don’t need to be replaced or trimmed.  Most will recover in the fall or disperse seeds that will return with new plants in the spring. 
• Avoid Shearing or Pruning – A healthy plant is the best defense against severe conditions.  Shearing shrubs or over-pruning trees causes overall extreme stress and sunburn to the plant's interior or bark of a tree, which can compromise water translocation of the plant.  Dead leaves hanging on to stressed plants offer shade and should not be removed until late summer/early fall, depending on the plant and how it responds to the lower temperatures and humidity.

As we move past this summer, be patient with plant recovery and heat damage remediation this fall. Here is a recap of what you can do to address heat stress in the future:

• Proper hydration ahead of, during, and after a heat event.
• Plant selection for different microclimates.
• Proper agronomics: pruning and fertilization should be timed with seasonal growth surges of each plant species.
• Soil health is essential for mitigating plant loss during extreme heat or even cold events; use organics to help improve soil conditions which can help increase plants’ heat and drought tolerances.

ALCA has many resources: educational programs throughout the year, a plant pruning guide, and the new Sustainable Landscape Management® book. We encourage you to be familiar with these resources and share them within your community.  Knowledge is power!