Some gardens increase fire risk. Other gardens may diminish fire risk and even reduce the damage caused when a fire does occur.
Knowledgeable gardeners – amateur or professional – can make better decisions about garden design and ongoing maintenance when they consider fire risk.
Ill-informed people might think the best way to avoid a fire is to clear all trees and tall plants away from their house. Reality is a little more complicated though. When a building doesn’t have plants around it, it becomes more exposed to wind and heat. Embers can be carried long distances by wind in a firestorm, and buildings can ignite up to tens of kilometres from a fire front.
Totally eliminating a garden does not guarantee protection from fire. Smart landscaping may not guarantee 100% fire protection, but it is probably a better solution.
Ignorance of plant selection, garden design and property maintenance can often heighten fire risk in fire-prone areas.
Fire can damage gardens horribly, some gardens more than others. Some plants and landscape materials will burn far more readily.
There are three important areas that need to be considered-- garden design, plant varieties used, and garden maintenance.
1. Garden Design.
In some ways, plants can help in fire zones, so long as they don’t catch on fire themselves. Plants keep an area significantly cooler, and filter pollutants including smoke from fires.
Placement of plants can change the way air moves through and over a property. Clear access routes need to be designed into a garden. A wide track with stone walls on either side will give better access than a narrow track with overhanging, highly flammable trees. When choosing landscape materials, favour materials that are less likely to fuel a fire or be damaged by a fire. Wood decking will burn, but masonry paving won’t. Some mulches burn more readily than others. Some soils hold more moisture than others. Water features may offset flammability. Extra water storage may enable better firefighting. Irrigation systems can be used to wet a garden when fire approaches.
2. Plant Selection
Some plants are less likely to burn or may not burn as fast. These include plants with watery foliage like cacti, ones with a high salt-content (e.g. Tamarix), ones with dense, insulating bark and ones with dense crowns.
Plants that burn more readily include ones with volatile oils in their foliage such as eucalypts, and those with fibrous loose bark, dry foliage, or resinous foliage like conifers.
Some plants can recover better from fires than others. Knowing how well a plant can recover is an important consideration when choosing plants to grow in fire prone areas.
A very high level of plant knowledge is critical to better fire management through better selection of plants for gardens, farms and landscapes. Sadly, there has been a decline in teaching this aspect of horticulture over recent decades in many countries.
3. Garden Maintenance
It is paramount to keep burnable material cleared from gardens as much as possible during fire seasons. Remove low hanging branches and flaky bark that might ignite trees.
Keep trees and shrubs watered, if possible, over summer with drip systems located on the windward side of the garden. This keeps water levels higher in plants and makes them harder to ignite.
Dig in any dry mulches or leaf litter that might ignite.
Flammable mulches such as lucerne hay are better used after a fire season. They can then settle and largely decompose before the next fire season. This can improve a soils capacity to hold water; and plants therefore may have higher water content if faced with fire.
After a fire, act to help a garden revive as soon as possible. Adding bio-stimulants, mulching, watering and pruning can help damaged plants revive. Sometimes though, a burnt soil can develop water resistance. If this occurs, digging the soil surface and/or using a soil wetter may be needed.