Pia Finnigan of The Arboricultural Association of Western Australia – ArbWest – champions the use of an often-overlooked product: mulch.
As Western Australia is experiencing another long, hot summer, tree care shifts from a seasonal consideration toa priority. Soils heat quickly, moisture evaporates almost as fast as it’s applied, and even hardy native species can struggle under prolonged heat stress.
Yet one of the most effective tools for supporting urban trees through summer remains surprisingly simple: mulch.
Often underestimated, mulch locks in moisture, suppresses weeds that compete for water and nutrients, and steadily improves soil health as it breaks down. Mulch doesn’t just help trees survive summer – it helps them thrive.
Keeping every drop where it belongs
Few environments test trees like a Western Australian summer. High temperatures combined with sandy soils mean water is easily lost before roots can benefit.
A well-applied layer of coarse organic mulch can reduce evaporation by up to 70 per cent, allowing moisture to penetrate deeper and remain available for longer. For young or recently planted trees, this can be the difference between establishing a strong root system and limping through the season under stress. Mulch effectively moderates soil temperature, protects fine feeder roots, and creates a more stable growing environment during extreme heat.
Starving the competition
Mulch is also a defence. By blocking sunlight from reaching the soil surface, it suppresses weed growth and limits competition for water and nutrients – an advantage when resources are already scarce. In urban landscapes where trees are often surrounded by turf, garden beds or disturbed soils, this weed-suppression effect reduces maintenance requirements while giving trees a much-needed edge during summer.
Building better soil, slowly
As organic mulch breaks down, it feeds soil microbes and gradually returns nutrients to the soil profile. Over time, this improves soil structure, boosts biological activity, and enhances water-holding capacity. The result is healthier soil that supports healthier trees, not just in summer, but year-round.
These benefits were front and centre at ArbWest’s ‘Beneath the Canopy’ seminar at the WACA. Speakers including Julie Fielder and Jeremy Thomas explored the role of fungi, composting, and soil biology in building resilient urban canopies. Julie described fungi as “…the planet’s original recyclers”, highlighting their role in nutrient transfer through underground networks, while Dave Crispin reinforced how correct soil preparation and organic inputs can save thousands of dollars in long-term tree management.
Mulch sits at the heart of all these processes: feeding fungi, improving soil structure, retaining moisture, and reducing stress during summer extremes.
Looking ahead
As summers grow hotter and water becomes an increasingly precious resource, practices that protect soil and support tree health are no longer optional – they’re essential. Mulch remains one of the most cost-effective, accessible tools available to arborists, councils, and land managers.
With the right machinery producing the right mulch, arborists are better equipped to build resilient landscapes from the ground up.
Better mulch starts with better machinery
The design of chippers and mulchers directly influences the quality of mulch produced, and according to Jesse Boshier from Tree Care Machinery (TCM), Bandit equipment is purposebuilt for demanding Australian conditions.
“Bandit machines are incredibly strong, reliable, and efficient for all operators and applications,” Jesse said. “Hydraulic controls increase reliability, efficiency, and serviceability in the hot, dusty, high-vibration conditions in WA.
“The design of the drum, anvil, knife mounting, and horizontal-feed system all contribute to excellent cutting technique and a high-quality chip or mulch.”
For arborists, that means mulch that breaks down more evenly, spreads consistently, and delivers soil benefits, rather than simply acting as surface cover.
“TCM is nationally backed and supported,” Jesse said. “Our support network goes far beyond the sale. We pride ourselves on our backup and after-sales service, and we truly value being part of our customers’ businesses.”
Keep an eye out for ArbWest’s upcoming seminar announcements, where the conversation around
trees, soils, and urban resilience will continue.
All events are advertised at arbwest.com.au.