How to select plants that survive a hotter, drier future

Gardening · Published 7 October 2026 Swipe more like this →

In short: As urban heat islands intensify, gardeners face a growing dilemma: how to choose plants that won't perish when the climate shifts. Scientists are now simulating extreme droughts and heatwaves to identify resilient species before the heat arrives, helping to ensure that greenery continues to provide essential shade and cooling.

In cities, the 'urban heat island effect' magnifies rising temperatures as concrete, asphalt, and roof tiles absorb and radiate heat. To combat this, researchers at Western Sydney University, including Professor David Ellsworth and Dr. Linda Beaumont, are investigating which species can withstand these intensifying conditions. Their 'Which Plant Where?' program uses climate-controlled glasshouses to simulate extreme weather, specifically modeling five weeks of drought followed by six days of heat. This phenomenon is particularly intense in urban areas where impervious surfaces like asphalt and concrete trap heat. Such temperature spikes can be mitigated by increasing greenery and street trees to provide essential shade.

This research aims to identify the 'permanent wilting point'—the specific level of soil moisture below which a plant can no longer recover. By understanding this threshold, scientists have already identified over 7,000 species that may remain useful in changing urban environments. For example, the Wilga (Gijera parviflora), an evergreen tree common in the Wagga Wagga and Mildura areas, is a candidate for future resilience.

For the home gardener, the strategy for longevity is to look toward the future. One effective approach is to select plants from regions that already experience the conditions you expect to have in the future. While planting Mediterranean or exotic species can help, there are risks; these plants may still face occasional unseasonal frost damage. Choosing trees that match current soil and site conditions is a safe baseline, but for long-lived species, the climate they encounter at maturity may be significantly different from the one they were planted in. However, gardeners must remain cautious when selecting species for long-term resilience. Increased drought frequency may cause timber defects like drought crack or lead to limbs dropping spontaneously. Furthermore, wetter winters could encourage more active root pathogens, potentially causing serious damage to root systems.

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