Australian Succulents

Fire and fire-safe gardening

There are various articles and snippets of information within this website that can greatly benefit gardeners who wish to use succulent plants in their gardens as a fire barrier, or to at the very least help reduce the impact or damage wild forest fires can produce. Reports are common, of succulents helping save houses from nearby forest fires, while houses next door had burnt down.

We, at australiansucculents.com grow thousands of succulents both in pots and also in open garden. Much of our work is in plant trials, that is trialing plants for suitabity in a range of situations, that we then can recommend to other professional growers and home gardeners alike. While we grow succulents from around the world, we are best known for our work developing and promoting Australian native succulents. Perhaps lesser known is that we also have growing trials for many Australian native plants besides those that are regarded as  succulent. These non-succulent Australian native plants are collectively catagorized as xerophytes, which are plants that can survive and grow with minimal water needs. And while native succulents are also xerophytes, these other plant types survive the same conditions as succulents by having either deep roots, tap roots, bulbs or other evolutionary adaptations to help them survive various levels or dry soils for extended periods.

Now, it is worth pointing out that we also have considerable interest in, and the understanding of, all our plants in relation to their response to fire. Most importantly with regards to Australian native succulents and other Australian native xerophytes that can and will grow well and asthetically together, but also providing a contributing factor to a safer 'fire-safe' garden.

Our display gardens in Narre Warren North, Victoria are situated on the fringe of Melbourne's suburban sprawl. Simply, we have suburbia on on one side and the other side with parkland reserves, creeks, hilly farmland and a national park viewable across the valley (Churchill National Park and Lysterfield Park).

Our property directly overlooks a park lake and while we have what's considered a very safe area where the risk of forest fires ever reaching us is considered highly unlikely or seemingly impossible, yet we have had some shocking experiences since our 2002 purchase of the property. The local council as a result has created a large cleared area (on one side of the lake) with a sign alerting people to muster on it in case of fire storms (or similar emergencies), that should threaten them or their homes in the area.

Well it is easy for me to exaggarate any fire experiences we have had so I will instead show some images of several fires viewed from or near our property that have occurred since we have been there. In the summer of 2003 we had a large grass fire spread across and over the hill as marked with rightside arrow. A week later this image was taken and smoke can be seen rising in the left side, more forested hills which were now on fire (left arrow). Our new garden is in the foreground with Michele using a hose to water a recently planted garden bed of echeverias.

Black Saturday fires in 2009. An aerial photo of our lakeside (yellow arrow) and our garden alonside which has the conifer boundary. Note the significant burnt areas, still smoldering the following day.

The Narre Warren fire was attended by fire trucks and a waterbombing helicopter that refilled with water from this small lake. Houses, outbuildings were destroyed and property damage was extensive, but many houses were saved. This house in the foreground was in the direct path of the fire which swept up the valley and creek leading towards the lake. Strong gusty northerly winds helped fuel the fire that swept along a forested creek-line.

Part of the Narre Warren creek-line ablaze.

I certainly thought that any fire that swept up the forested creek-line would have been stopped when it reached the lake, but it did not. Even the fire brigade, fire trucks and firebombing helicopter were challenged by how big the fire was developing after the fire swept around the lake perimeter to reach a larger open forest where further buildings were damaged or destroyed.

A few years later, on the 14th of February 2012 the below image was taken from within our now more advanced garden. The yellow arrow points to a fire in the nearby forest.  Almost every year fires are deliberately lit, by special fire management teams to reduce fire fuel accumulation. While these are important practices, (usually in cooler weather) with proven benefits, these burning practices have occasionally lost control of fires, especially  when there are sudden or strong wind changes. Several major fires across Australia have occurred through escaped 'back burns' also called 'controlled burns'.  This was a hot dry day with me in the left of the image with a hose watering.  Closer examination of the lake perimeter show thousands of native grasses and trees that have just been planted.

After the Black Saturday fires of 2009, I contacted the local council and its planning department, regarding offering fire-retarding native plants, notably Doryanthes, Brachychiton and succulents. We had hundreds of spare to our needs. I also offered my services as consultant or with help to plant them around the lake reserve. Several attempts to make contact with council by phone, emails and leaving printed brochures of my work. I felt that my qualifications were perhaps not academic enough to warrant their serious consideration. Another more likely reason included the fact that  Government directives to councils Australia-wide were to prioritise using local species of native plants in public spaces (mine were not local species). Hence the image above shows the lakeside margins with thousands of plastic plant guards for local grasses, shrubs and trees. I guess this is all understandable planning, however after almost 10 years since planting, everything has grown. Some parts of the lake perimeter had grasses planted and these are now thickets that in summer have a very high biomass of dry flammability, while the centre back part of the lake perimeter (as seen in the previous burnt out image above) is now heavily forested. The lake surrounds have become far more of a fire risk than they have ever been.

The image below was taken in March 2013 showing park rangers and fire crews once again back-burning in the nearby hills. Perhaps more important to the narrative now is the obvious eucalyptus street tree plantings here. This same tree species, Eucalyptus scoparia was also planted alongside our garden perimeter, at the same time as those in the image here were planted. The internet and some sources list this tree species as growing into a small to medium sized tree. Yet now as I write it is April 2020 and most of these street trees seen here and outside our garden are unquestionably LARGE already!

Most academic experts would be the first to agree that all eucalyptus trees are considered high fire risk. Interestingly about 8  Eucalyptus scoparia were planted only two metres from our property boundary now having branches so high and leaning over, that we are having regular leaf shed into our garden and onto the succulents. For the most part this is only a minor inconvenience and we can use a blower or garden vaccuum to dislodge dead/dry leaves from covering or at times smothering smaller succulent plants. Over time we have found various ways of making it easier on ourselves. We quite like the challenge. But at the same time I need to point out that any tree that produces continuous leaf drop like this is going to require very regular clean-ups, so as not to let volumes of leaf litter accumulate. If left unchecked some small flatter rosette succulents we found tend to suffer the most. As to any potential fire fuel, these leaves are considered high risk.  It is also common knowledge that eucalytus leaves contain oils that are combustible, hence increase  their leaves fire risk further. I have noticed something else about these eucalyptus leaves, perhaps worth a mention. At any given time or day of the year some leaves may be falling. The tree has many leaves still attached as its canopy, some of these are young and freshly developed, others maturing, others already mature. With all these changing stages there are leaves coming and going almost daily. But what of the leaves preparing to fall tomorrow or next week. Are these almost expired leaves already reducing moisture content, well before their last day on the tree. My point is that the leaves on the ground have already fallen, I feel that the (still greener) leaves on dry thirsty trees, that are pending shedding for the coming few days are the greatest single fire risk on (at least these) eucalyptus trees. These almost shedding leaves are the most primed to detach in strong windy fire storms.  These leaves are the driest on the trees and so are easiest to ignite, then detach, then travel the greatest distance carrying fire with them. Just my opinion, so please dont take it for fact! I was just very curious as to which part of my now towering eucalyptus is the most hazardous to me and my neighbours in the event of a major fire in my neighbourhood.  In very  windy weather I notice that these leaves when already fallen to the ground tend not to blow as far or high off the ground, instead they mostly get caught by ground cover succulents plants and here the leaves tend to remain permanently until decomposed. So it is my belief that the biggest fire hazard to all the homes around here are from semi-dry leaves, that are still attached high in the trees canopy. When canopies of eucalypts are exposed to flames fanned by strong winds it is these leaves that will travel the furthest and start the most new fires.

Wattle trees (Acacia species) are understood by all experts to also be very high fire risk. While none of this matters to anyone living in a city or suburban garden, it is important to us here on the fringe of suburbia where these types of plants and fire are more common. To people who live in forested areas, some of this information can become helpful or more criticaly important, especially if gardeners want to plan a safer environment around their homes.  Most Australian wattles are regarded as small to medium sized shrubs or trees that are also regarded as relatively short lived often with lifespans of only 5- 15 years.  Many popular wattles also have a tendency to develop random dead branches full of dry twigs that can look unsightly in otherwise healthy trees. Wattle trees have many parts that can readily burn fiercely. The leaves (or phyllodes) that are on the plants, about to be shed, or those already on the ground beneath are  a continuous fire hazard year round, just like the eucalypts. The fire-fuel contributing factors are only compounded by having these two types of trees (eucalypts and wattles) growing together or near each other. Wattles often have low branches that can typically reach the ground, as if shub-like, can draw fire up through their canopies to send flames several metres higher, that routinely in forest fires reach the upper canopy of taller eucalypt trees. Wattles, during fires contribute greatly to clearing competing tree canopies around them.

Not all wattles are as bad as each other. Some are infact slow-growing, some extremely so, like Acacia peuce hence will rarely reach any size to be a risk in most garden situations. Some have no true leaves (to shed any fire-fuel). Some xerophytic species such as Acacia aphylla, produce only a few leaves when they are seedlings, then remain leafless for the rest of their lives. This species does not produce phyllodes either so cannot produce any shedding fire-fuel, except perhaps any debris produced from its comparatively small flowers and fruit.  Only dead plants of A. aphylla contribute any significant fuel to fires. This makes it a good choice for gardeners who want a low-maintenance  wattle, that produces extremely low levels of litter and fire fuel, that only requires once a year tidy -up or removal of any dead branches or plants. We have been trialling A.aphylla with hundreds of specimens over the years spread out through our garden, in a range of positions and soil types. Specimens can reach 2 metres in height, where we then routinely cut them back to short stumps, afterwhich they will most often re-sprout vigorously with the best spectacular blue displays. We have had so many visitors impressed by our A.aphylla plantings over the years that everyone seems to want one. We now sell thousands of seed of this species, have written articles about it, as it is so popular (one of which can be found with photos from our garden, on this website). We even have produced a new and expanded small book about a range of mostly short and highly attractive garden worthy wattles that are mostly very worthwhile, low maintenance, and fire safe (at least being safer than many common wattles that have been more problematic during forest fires). This publication and (home grown) seeds of A.aphylla can also be purchased on this website.

Above image taken in 2016 in our garden looking east, towards two neighbours' houses. It is extremely hard to see the house roofs, so two yellow arrows point to what may just be visible if you look closely. Many shrubs and trees (the tallest ones in the far background are all eucalypts) have grown well over the years.  Like the neighbours, our one acre garden was once also bare, now it is mostly filled with vegetation of lush-looking nature. Fire safe garden planning has always been  a design element from the start. Almost all of the many trees and shrubs we planted, are pruned to keep them under 3 metres in height. Plant selection and placement is mostly strategic. The scope of this article and website is limited, in regards to all the varied things we have implemented, nor  will we list all the plants used, or how and why we incorporated each of them. However we do take guided tours through and around our gardens where much of this can be viewed firsthand and explained in situ.  Blue Acacia aphylla can be seen in the foreground here.

From 1990-1999 I lived on a more rural (10 acre) property that was surrounded by mature eucalypts. It was in these years that some of my earliest thoughts on fire safety strategies started to formulate.

Above image: Hardly scientific, but none the less, prior to having barbeques, I would routinely test out some of our plants for flammability. The two outside yellow arrows point to a Doryanthes palmeri stem, the inner yellow arrows point to Xanthorrhoea glauca inflorescences while the blue arrow points to Acacia aphylla stems.

We travel frequently and stop especially if a fire is underway or an area has been burnt prior. This is a typical Australian scene where grass trees (Xanthorrhoea species) dominate. In the foreground we found red Calandrinia corrigioloides growing around them. It is not only interesting but much can be learnt from such dynamic events.  For more on this aspect of our work, see our publication on this website titled Australian Grasstrees and Kingia co-authored with Neil Marriott.

An important disclaimer.

My article here, my opinion here, my observations and experience with wattles and eucalypts  are my own and do not represent how these plants can or will perform in your gardens elsewhere, or how they will behave in fire situations. Rather, my aim and work is to encourage other gardeners to consider some of the plants and points I make about them. Another primary aim of this article is to show how fire effects us on a personal level and also how it may impact us more so in the future.

And lastly, we at australiansucculents.com also have considerable experience  trialling, growing  and promoting a  range of other interesting waterwise native plants (apart from just succulents) we recommend for gardens in high fire risk areas of Australia. We spend at least 6-8 weeks each year travelling Australian natural habitats to study native plants, often prioritizing locations that have been burnt prior. After 25 years of observations and record keeping, we feel confident that we have sufficient knowledge and experience now to advise gardeners safely about the select plants that we focus our career on - low water, low maintenance, low risk native succulents, shrubs and trees. For example scientific or academic credentials are important for some experts to extoll, we only have tried and tested experience spanning decades. Our only comparative credentials are that we still have hundreds of:

Acacia aphylla, Doryanthes species, Brachychiton species that we grow and from which we harvest our own seeds which we supply to others. Few if any Australian growers have such stockpiles or experience.

These are samples only of plants that we intimately know and grow and promote with passion. Please enquire about others! And no, we don't claim to be experts on 'all plants', nor do we claim anywhere that we are experts on 'all native plants', but rather only a select range that we can back-up with evidence coupled with our large display gardens and  our publications on the topic.

Attila

Update: May 2021

A valuable new book is just out titled SAFER GARDENS Plant Flammability & Planning for Fire by Lesley Corbett 2021, Australian Scholarly Publishing, North Melbourne, Vic. It contain vast amounts of comparative scientific data from across the world about garden plants and how they respond to fire. The aim of the book is to provide gardeners with a better understanding of plants and plant choices, in relation to safer homes under potential threat from forest fires. This book is highly recommended, especially if you are planning a new garden or wishing to renovate an old one to make it safer. In context of this website, Lesley has consulted succulent experts from here in Australia (including us) and also the USA (Debra Lee Baldwin). Visit: www.firesafergardens.com

Ps. More on the topic of fire and succulents, next page below.

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