Maintaining and managing your garden for the bushfire season...

Part 6

Establishing a new garden takes time, and to ensure that is effective in the years to come it will require regular ongoing maintenance to protect the defendable space around your home.

Regular maintenance actions for the garden as part of your Bushfire Survival Plan should include:

• Clear ground fuel from underneath plants and around the house.  

• Re-mulch with non flammable materials, such as stone, shells or other non-flammable materials.

• Prune plants with low hanging branches, providing separation of at least 2m from the ground.

• Replace diseased, stressed or dead plants.  Ensure to replace with low flammable plants as per my previous post.

• Keep plants well hydrated through watering and mulch.  Watering less frequently but for longer encourages the plants to develop deeper roots and therefore reducing moisture loss during hot spells.

• Remove other flammable objects from within your defendable space.

• Remove any fine, dead material that has accumulated within plants.

• Remove weeds from the defendable space.

• Mow lawns and keep regularly hydrated.

(source: CFAVIC Landscaping for Bushfires, 2011)

(all photos in this article by: Kerri Fennell)

Please stay safe for the rest of this bushfire season.  That is the end of this series of posts.  Im really looking forward to sharing with you over the next few weeks some other things I have been working on lately.  How to make a pallet garden for your herbs, filing cabinet planters, design lessons learned along the way, and my week in Bali.

Perfect plants to reduce the intensity of a bushfire near your home.

Part 5

The next task, after planning and designing your home and garden, is to choose suitable plants. Selecting plants with some intrinsic characteristics, that reduce the likelihood of ignition, could help reduce the bushfire risk within your garden.

There are several characteristics that influence how flammable a plant is.  These are plant flammability, plant moisture content, branching patterns, texture, density, leaf size and shape, bark type, oils, waxes and resins, and the retention of dead materials.

Plant Flammability

Some plants are more flammable then others and the flammability can vary in unpredictable conditions.

Plant flammability can be described as a combination of

• the time taken to ignite
• how readily it burns
• how much material there is to burn
• how long it takes until all the available fuel is consumed

Flammability will vary depending on 

• a plants age, health, physical structure and chemical content
• the daily and seasonal climatic changes
• location of the plant in relation to other vegetation and flammable objects
• the specific part of a plant (some parts are more flammable than others)

Great spacing and plant selection, along with a stone mulch make this style of garden perfect. (Photo: Kerri Fennell)

Plant Moisture Content

Plants, such as succulents, with a high moisture content will not burn until the moisture has been removed.  Plants can dry out as a result of radiant heat, especially if they are exposed for long enough.

 Dry plants will ignite more rapidly and continue to burn until the source is removed.

Moisture content depends on a number of factors

• Time of day - before sunrise, plants are typically at their most hydrated.  As they transpire during the day the moisture content decreases until the plants stops after sunset.  Most plants are most flammable in mid to late afternoon.
• The season - In summer the soil dries out and the moisture content decreases
• Part of the Plant - Leaves and new growth generally have a higher moisture content than stems and branches.  Dead leaves and twigs have little moisture and become highly flammable on hot, dry days.
• Where it is planted - The sun and shade, availability of water, drainage and soil type will affect plant moisture.
• Environmental conditions - High temperatures, low humidity and periods of drought will increase the flammability of plants.
• The age of the Plant and its growth stage - Plants start as moisture rich shoots and become woody as they age.  The older the plant, usually the drier.  New growth is generally soft and fleshy.

Branching Pattern

This influences the distribution and density and foliage with the plant.

• Choose plants with an open and loose branching as well as leaves that are thinly spread, as plants with closely packed  leaves and branches have more fuel
• Plants with branches at least 2m above ground are better than those with foliage to the ground and stops the foliage acting as a ladder for fuels.

Texture

Coarse textured plants are less flammable than those with a fine texture, because they have a lower surface area to volume ratio.

Density

A plant that is hard to place a hand into, or see through is very dense.  These are often more flammable due to the higher fuel load.

Leaves

The fineness, size and shape of leaves affect their flammability.

• Wide, flat and thicker leaves usually means a higher moisture content, so therefore less flammable.
• Small, thin narrow leaves have a high surface area to volume ratio, which tends to make them more susceptible to drying out.
• Leaves with high levels of oils increases flammability.
• The shape can influence how easily they are caught in vegetation when they fall off the plant.  If leaves are caught in the plant this can increase flammability.

(source: CFAVIC Landscaping for Bushfires, 2011)

Agaves are perfect with large wide succulent leaves (Photo:Kerri Fennell)

Bark Type

Some bark types ignite more readily than others.

• Bark that is loose, stringy or fibrous will ignite easily and can also act as ladder fuels.
• Bark that attaches tightly or is smooth in texture is less likely to ignite.
• Some smooth barked trees shed their bark annually and trap large ribbons of bark in their canopy.  These ribbons are highly flammable and can be carried as embers and can act as a ladder fuel.

This bark is rough, but is held tightly.  As it starts to shed, it should be removed to avoid the hazard. (Photo:Kerri Fennell)

Oils, Waxes and Resins

Natural chemicals found in plants can increase their flammability.  These plants often have a strong scent when crushed.

These plants should be limited and placed carefully within the garden.

Retention of Dead Material

Dead leaves, twigs and branches that remain on the plant, or accumulate on the ground increase the flammability of an otherwise fire wise plant.  

Regular pruning and maintenance of all trees and shrubs to remove these fuels is necessary.

(source: CFAVIC Landscaping for Bushfires, 2011)

Dead leaves accumulating at the base of the plant increases fuel.

List of Plants and Trees suitable for a garden in a fire prone area.

Trees, Groundcovers, Climbers and Succulents

Plants

(source:http://www.dfes.wa.gov.au/safetyinformation/fire/bushfire/BushfireProtectionPlanningPublications/FESA%20Plant%20Guide-BP%20Zone-Final-w.pdf)(source:http://www.education.vic.gov.au/Documents/school/principals/infrastructure/bfpronelandsc.pdf)

Garden styles suitable for a bushfire prone area....

Part 4

In this weeks blog you will find some simple, practical examples of how you can apply the design principles outlined in last weeks blog, to some typical garden styles....

HILLS GARDEN

The hills of Western Australia generally provide excellent conditions to grow gardens.  The conditions allow for a wide range of plants to be grown successfully.

As a result, hills gardens often display great diversity and layers of vegetation.  Many gardens are located adjacent to national parks and native forests that are highly flammable.  The local site and context should be taken into careful consideration with each design.

This property is nestled into the side of a hill with national park beyond. This property required substantial retaining walls, which in turn would help to create barrier to a fire coming through.

COASTAL GARDEN

Strong seasonal winds, coupled with salt  can make establishing and maintain a coastal garden particularly challenging.  Along with sandy soils with poor water and nutrient retention, the addition of organic matter and mulches is critical to garden success.  Creating microclimates is the key to a successful coastal garden, by providing shelter and screening to maximise these problems.

This house, very close to the beach is subject to constant high winds.  Any fire coming off the dunes needs to be quickly stopped before it consumes the house.

SUBURBAN GARDEN

Recently, severe fires have moved beyond the rural fringe and into our suburbs, especially as many of our new  suburbs are creeping into the outskirts of the city.

The planning principles from last weeks blog, should be followed as closely as possible, given the limited suburban space you may have.

Luckily for this house, they have quite a substantial sized block, compared to a lot of the new suburbs being currently built.  However, the same principles apply.

RURAL GARDEN

Many rural gardens are on large farming properties and the house and garden location should be considered carefully, along with the placement of other structures, elements and services.

Paddocks surrounding a house can quickly dry out over summer causing fire to spread rapidly. The defendable space around the house is the most critical component, along with good planting and design strategies.

Also note that the house position is relatively close to the roadway and the driveways give fire trucks and other services plenty of room to access the property.  This property also has a 5m wide fire break around its entire perimeter.  The neighbours each have the same, therefore creating a good sized 10m fire break around their properties.

In next weeks blog we will look at what plants you can put in your garden that will reduce the chance of ignition, or lower the intensity  of the blaze.

Can you bushfire proof your home with smart landscaping?

Part 1

Photo source: Pinterest (Teresa Meyer)

The correct answer here is NO... But you can go a long way to reducing the risk of a bushfire destroying your home by knowing some of the ins and outs of what drives a bushfire.  By planning the layout of the home and surrounding garden, adopting some smart planting ideas, and with regular maintenance and management you can dramatically reduce your chances of losing your home to a bushfire.

Planning ahead is essential for surviving any bushfire season and the most effective way to do this is to reduce the location and arrangement of fuel around your home.  

All plants will burn, given enough heat, but measures can be taken to reduce the intensity by carefully selecting the correct garden plants.

Landscaping for bushfire means the planning, designing, planting and management of the areas around the house.  The aim is to keep the areas closest to the house and other structures of the property free of plants and trees that easily ignite.

Over the next few weeks I will look at each of these areas, a bit more in depth, with a 6 part series, to help you stay safe in summer.

Photo source: Pinterest (http://25.media.tumblr.com)

But firstly, we need to look at how fire behaves.

There are 3 main factors that effect how a bushfire behaves, topography (slope), weather, and vegetation (fuel).

Topography - fire races uphill.  As the slope increases, the faster the fire races.  

Weather - hot, dry, windy conditions dry out vegetation and provide ideal conditions for a naked flame to take hold.

Vegetation - plants are the primary source of fuel for a bushfire. 

The amount of fuel available to a bushfire and where the fuel is located can directly impact on house survival. 

Fuels such as fine leaf litter easily dry out, ignite and can be carried as embers. Shrubs, vines and other elevated fuel can act as ladder fuels, allowing fire to climb into the canopies of trees, significantly increasing bushfire intensity. 

(source: CFAVIC Landscaping for Bushfires, 2011)

Photo source: Pinterest - KateHamilton-Hunter 

Breaking up the continuity of the vegetation, with irrigated lawn, hardscaping, pools and other water elements, can limit the spread of fire within the garden.

Remember there are no ‘fire proof’ plants. All plants can burn under the right conditions – typically in extreme fire weather following extended drought.

Photo source: Project Artichoke - Kerri Fennell

House survival is influenced by many interacting  factors. The four main ways houses are destroyed during a bushfire are:

Ember attack - ember attack is the most common way houses catch fire during a bushfire. Ember attack occurs when small burning twigs, leaves and bark are carried by the wind, landing in and around houses and their gardens. 

Radiant heat - Is the heat created from combustion during a bushfire. It can ignite surfaces without direct flame contact or  ember attack.  It dries out the vegetation ahead of the bushfire so  that it burns more readily.  Can crack and break windows, allowing embers to enter a building, and distort and melt materials such as plastic. 

Direct flame contact - occurs when flames touch an object.  Any burning vegetation can directly ignite a house if it is planted in the wrong location.

Wind - can be very destructive to houses in a bushfire because it carries embers,  causes trees to fall onto buildings, breaks windows, loosens roof tiles and can even blow roofs off houses under severe conditions.

(source: CFAVIC Landscaping for Bushfires, 2011)

In my next instalment of this six part series we will look at ways of reducing these risks to your home, with better planning, especially if we can get involved in the early stages of the home design.

Sign up to receive the series, that will inform you how to plan for bushfire, design the garden and the best plants for bushfire prevention and management ......