How Australian Native Plants Adapt to Fire and Tips for Fire-wise Gardening

Australian Native Plants Adapt to Fire

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The beautiful area we live in is surrounded by thick bushland that thrives after fire. In fact, many native plants rely on it to survive. Australian plants have made many survival adaptations. Eucalyptus and banksias have a unique lignotuber found in the underground stem or root system that is filled with starches and dormant buds that spring into action after fire or stress, producing a mass of new growth.

The same goes for epicormic buds found along eucalyptus tree trunks and branches. The sole purpose of the mass of growth that comes from these buds is to reproduce the parent plant by making seeds as quickly as possible to recolonise the bare soil.

The growth from epicormic buds is usually weak and will easily fall after strong winds. This is something to be mindful of if you have recently had back burning nearby or a tree pruned and any new shoots hang over your home. Many native plants need heat to crack open thick, woody seed pods or smoke to germinate the seed. And without fire, many plants are unable to propagate. You can now buy smoke water to germinate seeds. Some natives, such as our precious Illawarra flame tree, take up to seven years to be mature enough to produce seed. In areas that have regular fires, this has prevented these plants from ever growing back, thus changing the landscape forever.

Melaleucas (paperbarks), Casuarinas (she-oaks) and Acacias (wattles) regrow from seed very quickly after fire and can recolonise, creating monocultures in once-diverse environments. In most areas this is OK and these speedy plants act as nurse trees, providing shade to a few slower venerable saplings. By the time the quick-growing nurse trees die, the other slower species can then dominate the canopy. But in areas that have had many fires in close succession only the quick-growing plants survive. Amazingly, some native seeds can stay dormant in the leaf litter for many years, waiting for fire to trigger growth.

How to prepare

It’s good to prepare your garden and be fire-wise. Limit potential hazards: trim back all tree branches hanging over your home; this will also lessen leaf litter that can fill your gutters. When removing or pruning large trees, always consult your local tree surgeon and ask your council’s tree management officer for permission. Remove all dead growth from shrubs and trees. Regular pruning of grasses and shrubs will keep plants lush with water-filled new growth and lessen the chance of woody die-back in the future.

No plant is completely fire retardant, but some will burn a lot slower than others. Limit woody, dry-looking shrubs such as she-oaks and conifers. These have lots of dead wood and very flammable needle leaves. Eucalyptus is filled with gum that will explode when branches become very hot in extreme fires.
Limit plants under your eaves and choose plants with lush leaves that hold water. Examples are succulents, camellias, gardenias, lillypillys, viburnums, ‘Little gem’ magnolias, groundcover Myoporum, Scavoleas, pigface, clumping gingers, kangaroo paws, Lomandra longifolia ‘Tanika’, clivias and the always-resistant agapanthus.

Agapanthus and oleanders have been used as fire breaks for more than 100 years in Australia. They were often planted around homesteads. I have seen footage of fire-devastated areas where the only things left were the rows of these hardy plants.

Mulch is very beneficial for retaining water in the soil. To limit any potential risk of mulch becoming fuel, rake up any pine needles and make sure to water down mulch well over the summer. Avoid large, chunky pine barks as they don’t break down very well or hold much water – go for fine mulches. I like decomposed cypress mulch and Helensburgh’s fire chief Jim Powell recommends teatree mulch. For more fire preparation tips and fire-resistant plant lists, consult the NSW Rural Fire Service website or Wollongong Council.

Stay safe over the new year and happy gardening!

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