When Plants Go Bad...

I have always wished for a horticultural equivalent of the joke: Q: When is a cook bad? A: When he beats the eggs.  I wish for this because gardening words are by their very nature only gentle or benign, even innocuous.  We prune, pollard, dig, churn, plant, nurture, grow, irrigate and pick.  We never slap or punch.  Nor do we beat. The words we associate with gardening are always positive and uplifting, or soul nourishing for some.  One of the things we gardeners have a hard time with is discussing gardening in negative tones, because we don’t like to think we do any harm.  Perhaps the biggest, unintentional negative that can result from gardening is the spread of weeds.  Having a joke to lead into a discussion of weeds would be very handy, so if there is a gardening joke out there that reflects this dark side of our craft I’d love to hear it.

I’ve spent the last few weeks working on Phillip Island doing a bit of weed control and ecosystem assessment.  Working on Observation Point on the Rhyll Inlet is one of the best offices in the world, but it’s a pity about some of the company.  Myrtle leaf milkwort (Polygala myrtifolia) has set up shop there in the past and has flourished to the point of what is now a major infestation.  In some areas the only local plants to survive the onslaught of polygala have been the very old silver banksias (Banksia marginata), which stand as pillars of resistance from the monoculture of milkwort below.  The experience got me thinking about how gardeners not so much consider weeds but the notion weediness.

                                        Before and after photos of removing Polygala myrtifolia on Phillip Island

I suspect everyone grows a plant that is either an already acknowledged environmental weed (the popular Zantedeschia aetheopica, for example) or has the potential to cause weedy infestations if they get away form us.  I myself am having a love affair with the genus Oxalis at present, a species of which, commonly referred to as soursob, is probably one of the most hated garden weeds of all time.  The genus Oxalis is a large one, with many redeeming members that get overshadowed by the black sheep of the family.  That being said, some of the species I am growing do have the potential to spread in the right conditions, but I have taken precautions to prevent this.  Apart from eternal vigilance, the best way to combat the potential weediness of plants we might grow is to know them intimately.  Knowing what conditions a plant thrives in as well as information such as the main method of spread are important in keeping them in check (as the saying goes, one year to seed, seven to weed).

The species of polygala we’re dealing with on Phillip Island is a common garden plant around Melbourne.  It will grow without any supplementary irrigation in most environments and flowers most of the year, producing seed in abundance.  There is nothing intrinsically wrong with the plant, after all it’s just doing its thing.  Where this milkwort crosses the boundary from pleasant plant to wicked weed depends very much on the location of the planting.  Polygala likes sandy soils and will quickly spread in costal ecosystems if left unchecked.  Birds will eat the seed it produces, so gardeners should keep in mind that the potential spread of some plants may not be limited to the yards in which they grow.  Birds can carry seed far and wide, but growers of polygala in the city areas need not worry too much about this – as with most weeds in bushland areas, residents bordering or close by these habitats that need to be the most vigilant.

One question I find difficult to answer is how vigilant must gardeners be with the potentially weediness of plants they grow?  There are so many factors to take into consideration that a simple, succinct answer is very hard to give.  I think most gardeners who know their plants will be very mindful of weediness no matter where they live.  Gardening novices, on the other hand, are more likely to be unaware of some plants’ weed potential, so I think education is part of the solution.  It is difficult to educate the public on what plant species do pose a greater risk of spread when so many declared invasive species can still be purchased in retail outlets.  Montpellier broom, Genista monspessulana, is a terribly invasive weed that you can still buy in many nurseries.  Ditto for ivy (Hedera helix) and honeysuckle (Lonicera japonica).  This then poses the often divisive question, is banning some plants part of the solution?

With that can of worm juice now well and truly open, perhaps we should all ask ourselves, what does weediness mean to me?

Until next time, happy gardening.

Autumn Colour - why is this year's so intense?*

In the last two years Eastern Australia has seen a spate of wet weather that is in stark contrast with the preceding ten years of drought.  Melbourne has been positively luscious of late, with plants of all kinds booming in the idyllic conditions.  With the months of lush, colourful flowering now well and truly behind us, autumn is a time to admire those trees and shrubs that brighten up the chilly mornings with their fiery displays of yellow and red.  Like flowering perennials and annuals that have been a dream to grow lately, so too has autumn colour benefited from the extra rain.  Here in Melbourne we’re having one of the most stunning autumns in a long time, even better than last year’s wow-fest.  The intensity of colours we are seeing in many of the deciduous species around town is breathtaking.  Reds, yellows, oranges and even purples are busily setting gardens ablaze throughout the suburbs, adding a warming glow to the slowly chilling streets.  The processes by which plants achieve such intense colouring are fascinating and, I think, as beautiful as the colours they result in. 

The summer equinox marks the point at which the days begin getting shorter, the sun gets lower in the sky and the hot summer temperatures begin to wane.  Deciduous trees then soon begin to prepare for winter by drawing nutrients in from the leaves to the branches and trunk.  Most of the nutrients that are broken down are the constituents of chlorophyll, the chemical compound that gives plants their green colour.  As these compounds are sequestered from the leaves into the branches, the leaves begin to change colour.  What colour autumnal leaves turn depends on the pigments left behind in the leaves.  Basically, there are two pigments that determine autumn leaf colour – yellow and red.  A plant may have either or both pigments present, it depends very much on the species.  Lots of plants have both, which is why you don’t just see either yellow or red during autumn but a whole spectrum of shades in between. 

                                         Pyrus calleryana cultivar showing red for the first time this year in my garden

The yellow pigments (carotenoids) are present in the leaves all year round, but they don’t come through because of the high concentration of chlorophyll in the leaves.  Red pigments (anthocyanins), on the other hand, are only manufactured by the tree towards the end of the season and are not found in great abundance in the tree throughout the year.  When chlorophyll and other compounds are broken down and absorbed by the plant during autumn, the presence of the yellow and red pigments in the leaf tissue begins to be revealed.  This is what we know to be autumn colour.  When conditions are right higher concentrations of these pigments are made by the tree, which is why, in good years, autumn colour is much more intense. 

                                                   Block-yellow of Liriodendron tulipifera is stunning in autumn

Temperature and sunlight in early autumn also play a role in colour intensity.  More red pigments are produced in the leaves if conditions are not only cooler during the night time, but there is lots of sunshine during the day too.  Colder temperatures don’t have to be consistent in order to get good colour – a few days or a week of crisp, cool nights is enough to get the ball rolling.  In Melbourne this year we had a cold start to autumn before the temperatures again climbed to the high twenties.  This has happened a couple of times over the previous month.  The clear, warm days amongst cold spells creates perfect conditions for the red pigments to accumulate rapidly in the leaf tissues.

Some of my favourite autumn trees and shrubs this year have not been remarkable performers during past autumns. Others are consistent performers.  One of trees to make an impression on me this year is a cultivar of ornamental pear (Pyrus calleryana).  The pear was an existing tree when we moved into the house and was one I had considered removing.  I’m glad to say I thought better of it because this year its autumn colour has been intense.  Last year we only got yellow coming through in the autumn, whereas this year we are getting reddy-oranges too.  In the afternoon light the tree looks like it’s on fire.  The colour is so intense it almost hurts my eyes! 

                                            Intense red this year on my ornamental grape arbor (Vitis vinifera)

Another surprise this year was the ornamental grape (Vitis vinnifera) we have growing over our back arbour.  When we moved in there were originally four plants that covered the arbour.  Anyone who is familiar with Vitis vinnifera will know well how vigorous it is.  Four plants to cover a 10 x 3 meter pergola is a bit over the top, to put it lightly.  The first year of pruning it took me three weekends of ladder and roof work, and the sheer mass of canes leftover once the job was done was staggering.  I ended up cutting three of the plants out completely the following winter, and retraining the remaining one.  This year’s good conditions saw the almost naked arbour flush out to a full and healthy cover in no time.  Opening the arbour up by removing excess plants has kept the grape fungus-free all year.  Consequently, the show the vine has put on this year far exceeds the others it has in the past.  The crimson red colour it turned this autumn took me completely by surprise as I had considered the colour of it in previous years as detracting rather that beautiful.  I think the lack of disease in the leaves played the biggest role in this year’s stunning display.  In previous years botrytis had made the autumn colour on the leaves patchy and sickly looking.  The lack of disease in the summer time has resulted in consistent colour throughout the vine this autumn.  This is a good example of how cultural controls (pruning) can be as good or even more effective than chemical controls (spraying with fungicide) when it comes to dealing with plant diseases

           

Another genus of shrubs putting on a great autumn display at this time of year are the sumacs (Rhus spp.).  Autumn colour tends to make genera such as maples, liquidambars, elms and oaks spring to mind, but big landscape trees are not the sole bastion of pretty autumn tones.  Smaller trees and shrubs abound with great autumn displays, the sumacs being amongst the most spectacular and reliable.  They are perfect for the city suburbs because most of them don’t get too large.  They are also good in areas with milder winters because they don’t seem to need very cold snaps to produce great colour.  The sumacs are sadly underrepresented in Australian gardens, but with the warming climate we are set to face in the future perhaps their stock amongst gardeners will rise with the temperature.  

                                               A sumac (Rhus spp.) putting on a dazzling show.

A word of caution on sumacs: a declared noxious weed in Australia is referred to in the vernacular as 'sumac' but it is actually a plant belonging to the Toxicodendron genus, not the sumac genus, Rhus.   Some species in the true sumac genus, Rhus, do have the ability to become weedy, so choose your species very carefully if you live in bushland areas.

There are still a few weeks of autumn colour left out there to see, so my advice is to go out and see as much of it as you can!  I read recently that the global climate pattern is showing signs of shifting back to El Niño once again, which results in drought in many parts of Australia.  So this might be one of the last years in a while when the colours of autumn will be this beautiful.  If you want to see particularly good colour then pack up the car and head for the hills – Mount Macedon and the suburbs around Mount Dandenong are putting on a wonderful show at present.

Until next time, happy gardening.

*This post has also appeared on gardendrum.com, beating a new path to gardening

                                              Autumn colour in Mt Macedon this year has been well worth the visit

MIFGS 2012 - The Award Winning Show Gardens*

With the whirlwind that is MIFGS now over for another year, it’s time to debrief what was one of the most successful shows in years.  The student design gardens this year were easily the most impressive in years, perhaps the most impressive in MFGS’ history.  For me, Rourke Hartwig’s design, ‘The Illusionist’, was the most impressive of the student gardens.  Rourke’s ability to play with space so seamlessly is well beyond his years.  He is a designer whose career I look forward to following with great excitement.  The Avenue of Achievable Gardens this year was also impressive, containing lots of easily adaptable ideas for many a gardener who set eyes on them.    The piece de resistance of MIFGS every year is of course the show gardens, where landscape design gurus battle it out with a flurry of flowers and lashings of landscaping for horticultural supremacy.  So who were the medal winners this year, you ask?

                                             Rourke Hartwig's inspired design, 'The Illusionist'

This year’s entrants included 13-year-old Adeline Dotchin’s garden for kids, by a kid.  It was great to see such a young gardening enthusiast out there having a go.  With a nod to Lewis Carrol, part of Adeline’s inspiration for her design was Alice In Wonderland.  For such a young’un to already have her first MIFGS show garden, this designer looked on with an impressed gaze and felt like he really had tumbled down a rabbit hole.  Adeline’s imaginative design earned her a bronze medal for her efforts, and it was very well deserved.  Well done, Adeline. 

                                                                    Dan Piper's bronze medal winning garden

Imagination and illusion were recurrent themes with this year’s show gardens.  Floating stairs and garden seats made highly effective appearances in two designs.  Dan Piper’s bronze medal garden featured a terraced-style complete with local Grampian sandstone steps that seemed to hang in mid air.  Sandstone makes a bold statement in gardens, particularly when used in abundance.  It can often be tricky to balance out with plants, particularly in smaller spaces, but the floating steps in Dan Piper’s design seemed to mellow the material to a subtle presence.  A floating garden seat featured under a shady tree in the garden ‘Surge’ by Candeo Design, which picked up a well-deserved gold medal.  ‘Surge’ was one of only two show gardens this year that was built to be seen from all angles – it was a truly 360 degree garden.  Personally, I like being able to walk around the showcase gardens much more than I do simply passing them front-on.  Viewers were enticed around the outside of ‘Surge’ by an impressive showcase of plants that framed the garden beautifully.

                                                                               'Surge' by Candeo Design

                                                                        Floating garden seat featured in 'Surge'

Another 360 degree-view garden was that of ‘Conversation’ by Paal Grant, which featured his trademark laser cut steel structures.  I particularly liked his use of Sansevieria to crown the tops of his serpentine walls and steel-cut pergola.  They highlighted that an imaginative use of plants, especially where you don’t often expect to find them, can fulfil the same vertical elements in our gardens that only trees seem to be able to provide.  Paal Grant earned a gold medal for ‘Conversation’, which is his second MIFGS gold medal. 

                                                       Paal Grant's 'Conversation', featuring an interesting use of Sansevieria

Another designer who picked up yet another gold medal this year was the ever-reliable Phillip Johnson for his garden ‘Equilibrium’.  Since bursting onto the design scene some 16 years ago, Phillip Johnson has established himself as one of the most ecologically minded garden designers in Melbourne.  ‘Equilibrium’ reflected his fundamental ecological principals of sustainable and smart water use by integrating the water used in Carlton Gardens into his design.  The water used in ‘Equilibrium’ was piped from one of the lakes in Carlton Gardens, removing the need to import water from mains.  This year’s design featured a small move away from Phil’s usual native Australian plant pallet to include a single specimen of Hydrangea macrophylla, which was used in the design as a bioindicator for water quality.  The idea behind planting the Hydrangea with its roots in the water, Phil explained, was to act as a system for monitoring the health of the pond.  As long as the Hydrangea stayed white, you would know that the pH of the water was neutral, which is a very smart way of keeping track of your water body’s health.  A great feature of this year’s design was a ‘before’ garden, which reflected the typical Aussie backyard before Phil and his team worked their magic.  It was a very smart inclusion, resulting in a contrast that made the finished garden really sing.

                                                                             Phillip Johnson's 'Equilibrium'

Better Homes and Gardens presenter Jason Hodges also picked up a gold medal for his creation, ‘The Sir Walter Spare Change Garden’.  It was a money saving design that was a bit out of the ordinary for a show garden in that the budget to create it wasn’t particularly substantial.  Featuring mostly recycled materials and reused plants, The Spare Change Garden was a testament to just how great a garden made from recycled materials can look.  Jason Hodge’s design showed all gardeners that an well presented garden does not have to equal an expensive garden.

The last gold medal on the list, as well as Best In Show, went to ‘Nord’ by Marnie Lewis.  ‘Nord’, or given the featured - literally cheeky - moulded seats, ‘Nordy’ was a nod to the Scandinavians and their thoroughly modern lifestyles.   It was a design that reflected the at times stark nature of the Nordic landscape very well, with its white painted brick and white pebble mulch.  The bare, grey timber decking and cladding echoed the rocky slopes adorned with conifers found in Scandinavia’s more mountainous regions.  The moulded plastic chairs prominently featuring someone’s backside caused quite a stir, with the general consensus being they were playful and a bit of fun. 

                                             'Nord' (or 'Nordy') by Marnie Lewis

With the dismantling of the show gardens at this year’s MIFGS now complete, planning and submissions for next year’s show will soon begin in earnest.  What will we see next year, I wonder?  Will nude-cast chairs suddenly be all the rage, much the same as how fire pits burned a hole in the creative mind of many designers in years past?  Will the concepts of the fire pit and nude-cast chairs combine, resulting in something totally new to both warm yourself by and ogle at?  I guess only time will tell.

Until next time, happy gardening. 

*This post has also appeared on gardendrum.com, beating a new path to gardening

More Trees, Please*

There are many services that combine to make a liveable city.  Effective sanitation, accessible public transport, well maintained public open spaces and recreational facilities are but a few such services.  Large amounts of council revenue are spent every year on such services, maintaining them as assets to benefit all citizens’ mental and physical wellbeing.  While the built environment makes up the more noticeable public assets cities possess, the living environment is equally important.  Parks, gardens and other public open spaces provide many widely acknowledged benefits to users, but there is one part of our urban environment that many people overlook.  I am talking of course about the humble street tree.  Those thousands of trees that line the city and suburban streets are sometimes maligned as much as they are marvelled at.  The consternation with which some people may regard their street’s trees is often misplaced or made out of a lack of foresight, because there is plenty to like about well selected and cared for street trees.  Not only can they look beautiful but their benefits range from cooling urban environments right through to economic benefits, such as prolonging the longevity of footpaths and roads, saving rate payers untold thousands per year.  Street trees are more of an asset than a liability, and here is a small showcase of some of Melbourne’s most beautiful, less well-known examples.

When thinking of street trees in Melbourne the classic examples first spring to mind.  Elms adorn many a city street and have become as synonymous with Melbourne as the clocks in Flinders Street Station.  As noteworthy as the elm population of Melbourne is, and as much as I adore them, there are many other tree species used in streetscapes around the city that deserve an equal mount of adoration.  Plenty are natives – even indigenous – and others not, but ‘native’ is by no means the definitive criterion when it comes to great street trees.  Reliable uniformity of trees is one of the most important considerations, as nothing looks more detracting than a street with unkempt trees, with the exception of a street completely denuded of them.  Many gum trees are considered ill-fitting street trees owing to their often highly variable form within species, but two examples stand out around Melbourne as exceptions to this rule.

                                                   The beautifully mottled bark of Corymbia maculata

The Spotted Gum (Corymbia maculata) and Red Ironbark (Eucalyptus tricarpa) are two native trees that lend themselves to use as street trees.  The latter is even indigenous to the Melbourne area.  The spotted gum is a handsome tree that is named so owing to its beautifully spotted bark, making this species a real feature when planted en masse.   Dark green foliage fills this tree’s canopy all year round and may reach a height of 20 meters or more.  Red Ironbark will reach a similar height but its appearance is all together different.  Where Spotted Gum’s bark is smooth and flaky, Red Ironbark is adorned with dark red/brown, highly fissured bark that really stands out.  The leaves have a blue hue to them that contrasts beautifully with the bark.  Unfortunately, Red Ironbark has developed a reputation for shedding limbs when stressed (a lot of gums do), which has resulted in them falling from favour with urban forest managers.  While this reputation is probably deserved, and prudence says they should be avoided in streetscapes for that very reason, the only streets I know of in Melbourne that are planted with this species show no signs of stress.  This is remarkable given that Melbourne has just emerged from over ten years of severe drought.  Could Red Ironbark’s resilience in tougher times outweigh the fear of dropping limbs?  I certainly think so, but convincing councils (and residents) is another matter entirely.

                                             A lovely street scape showcasing how great Eucalyptus tricarpa can look

Limb shedding is one of the main reasons why gum trees are often avoided when it comes to selecting street trees.  In a climate like Melbourne’s it too makes a great deal of sense to consider deciduous trees that let winter’s sun flood in unimpeded.  There are again many examples, one of the most successful as well as controversial are the Plane Trees (Platanus spp.).  Plane trees tick all the boxes; they are fast growing, widely adaptable to many soils, have reliable form (especially pollarded around power lines) and are deciduous.  The controversy surrounding their use in Melbourne is due mainly to their high allergen nature.  Anyone who suffers from hay fever is advised to think twice about visit Melbourne in the early spring, when plane trees release pollen in vast amounts.  Melbourne arborists consider the London Plane Tree (Platanus X acerifolius and cultivars) as over-planted around the city’s suburbs, and in many ways I agree with them.  However, when it comes to trees that don’t rip up paving as well as providing vast canopies of uninterrupted shade in the summer time, the London Plane is arguably second to none.  Love them or loath them, London Plane Trees have been a highly successful addition to Melbourne’s street tree taxa in recent decades.

                                        The dense, continuous shade provided by Plane Trees is second to none

A less controversial but equally successful street tree seen around Melbourne is the English Oak (Quercus robur).  This majestic species, as its name suggests, hails from the UK as well as most of Europe, and was widely planted around the city some eighty years ago.  Many plantings are only now reaching maturity, with many more being planted recently in areas such as South Melbourne.  The English Oak has the enviable reputation for doing little damage to roads and footpaths through its root system, which is one of the reasons why it was planted widely in the past.  It has a broad canopy and is a handsome tree that improves the look of any street it is found growing in.

                                                             English Oaks in Richmond

  

Finally, the City of Melbourne has recently announced an urban forest policy, which aims to double the amount of tree canopy cover across the municipality.  The policy aims higher than its concurrent replacement strategy, which sought to replace declining mature trees, particularly elms, in a bid to maintain Melbourne’s reputation as a leafy urban centre.  Although the current residents of Melbourne will not see the fruition of this latest policy, those who will call Melbourne home in a century or more will have a lot to enjoy in the city’s collection of trees.  Hopefully twice as much as us treeophiles do now. 

Until next time, happy gardening.

*This post has also appeared on gardendrum.com, beating a new path to gardening

The Aerobin 400 - The worlds most expensive compost bin*

Brand:  Aerobin

Model:  400 Composting System

Rating: 4.0/5

Likes:  Easy to assemble.  Comparatively little maintenance required in comparison to other composting systems.  Makes good quality compost relatively quickly (depends very much on what materials go into it).  Design eliminated the need to turn the compost, which is good for lazy gardeners!  Is easier to make good compost for beginners.

Dislikes:  Construction materials could be sturdier (claims to its durability have been over stated in my experience).  The draining spigot is too close to the ground – the bin should be assembled on a raised platform, like a few large-format pavers, to aid draining liquid.  It’s exorbitant price tag.

Overview:  When it comes to home composting there now many options to choose from.  The Aerobin 400 compost bin is certainly one of the more pricey options but you do get more bang for your composting buck.  Firstly, the capacity of the bin is much larger than other systems at a whopping 400 Litres.  This means that for the average suburban block, one bin is probably all you need.  It is designed to be maintained as a hot composting system, meaning that the turnarounds between the production of useable compost are comparatively faster and easier than other bins.  Claims to the Aerobin’s ability to make ‘better’ compost should be treated with a healthy amount of scepticism.  With apologies to Gertrude Jekyll, compost is compost is compost.

Features:  One of the keys to the Aerobin’s effectiveness is grandiloquently referred to in the literature as a ‘lung’.  It is essentially a segmented pipe that runs from the bottom chamber of the bin right through to the top, encouraging aerobic conditions inside the bin while discouraging the formation smelly, wet compost.  It is also insulated with polystyrene, which helps to keep the heat inside the bin over the cooler months.  It also has a reservoir at the base of it to collect the leachate formed in the composting process.  Finally, two large doors are located at the base of the bin for easy removal of compost.  The doors are large enough for easy access with a spade when it comes time to harvest your precious, black gold.

                                     The finished product - dark brown/black compost, even texture, no weed seeds.

Used by whom and where:  Owing to an unexpectedly large tax refund in my student days I was able to purchase the bin and have been using it for almost four years.  It works well if, like me, you don’t enjoy manually turning compost bins.  I live on a pretty small suburban block in the inner northern suburbs of Melbourne and it easily handles all the materials I put into it.  When I purchased the bin I was renting a house with a kikuyu lawn, so lawn clippings were heaped into the bin on a weekly basis in the summer time.  Each week I would fill the bin to capacity and each week the materials would cook down enough to fit the next load in – no turning required.

Performance:  Within the first couple of months a bit of trial and error was necessary to become familiar with what the bin required to work properly.  It is by no means a chuck-anything-in-and-forget compost bin.  A proper balance of brown and green ingredients needs to be added in order to have it work properly.  When I had an abundance of lawn clippings the system became too wet very easily, so careful attention was needed to ensure the conditions in the bin didn’t become anaerobic.  This was achieved with the addition of large amounts of dry ingredients such as raked up leaves, dry twigs and the odd bit of newspaper here and there.  The ratio of green to brown ingredients I have found work well are a little more than half green to every dry part, so between 2:1 and 3:1.  Thankfully, the house I’m now paying off came complete with two medium deciduous trees and a grape vine-covered pergola, which provide me with almost enough brown matter to last me all year.  The leaves and grape vine canes live in bags in the shed and are added to the bin when necessary.

             A proper balance of green and brown matter is essential for the bin to work properly

A note on the leachate reservoir at the bin’s base: I’ve never experienced the bin to produce any liquid in great quantities.  Which is a good thing because the spigot used to harvest the liquid is impossibly low to the ground, so much so that I imagine collecting the liquid would require a McGiver-like ingenuity to get at it.  Compost tea, as I’ve previously written about on here and on Garden Drum, is not all it is purported to be, so I’m not put out by my bin’s lack of leachate.

While the design of the bin is groundbreaking as far as compost bins go, I feel the design could be a little tighter.  There are many nooks and crannies in the frame that spiders like to take up residence in, not least of which are the handles on lid.  I always make sure I use gloves when dealing with the bin to ensure I don’t get nipped by an errant arachnid.

On a final note, the bin is not vermin proof.  I found this out the hard way when a pair of mice took up residence in the bin and soon burgeoned into an extended family.  The solution I came up with was to drill small holes in the leachate reservoir and block up the spigot hole completely.  Sacrificing leachate for vermin-proofing, for me, was a small sacrifice to make.  This problem can also be avoided by mounting the bin on a hard surface, such as pavers or concrete.

Specifications:

Dimensions: 740mm x 740mm x 1200mm when assembled

Capacity:  400L

Patented “lung” inside the bin eliminates the need for turning the contents.

Where to buy:

Many online retailers sell the bin, as well as most garden centres and nurseries.

Price guide: $350 - $380 RRP


*This post has also appeared on gardendrum.com, beating a new path to gardening

The Right Plant for the Right Spot*

Over a year ago now, friends of mine gave up their city slicker existence for what one would assume to be a more subdued life in the country.  Fresh country air, rolling hills, the serenity, the vibe – the picture they painted of their future was in stark contrast with their hitherto inner-city existence.  “It’ll be a real relaxing country place,” they cooed, making me green with envy of course.  What my friends imagined as their idyllic country cottage ended up being a forty-acre property in Victoria’s north eastern district, five of which was established garden that hadn’t seen a hand-weeder or pruning saw for almost two years.  To say the garden needed work when these friends purchased the property was an understatement.  A year or so on and the garden is looking a lot better than it did.  The last twelve months has seen a frenzy of pruning, weeding, mulching and composting on a scale unlike anything I have ever been involved with.  Yet much still needs doing in the garden.  Over last year’s Christmas/New Years break I had the opportunity to housesit for these friends, and of course I jumped at the opportunity.  The weather was not very conducive to gardening so I took the opportunity to don a deerstalking hat and have a snoop around the propagating shed for the ghosts of gardeners past.

The sheer size of the garden was suggestion enough that the previous owners were very serious gardeners indeed.  The contents of the propagation shed were definitive confirmation of this.  Misters, ultrasonic fogging machines, heated benches, solar coverings, hardening off areas, pots, labels, trays, fertilisers, and climatic control systems; every possible propagation toy imaginable was present.  I was in heaven!  Despite the volume of horticultural toys the object that piqued my interest the most was much more unassuming.  Upon rummaging through a set of cabinets full of plant ties and labels, I stumbled upon an unremarkable A4 folder containing some rather remarkable papers.  The folder was chock-full of the previous owners’ propagation notes, detailing the successes and failures in propagating hundreds of plant species throughout the garden.

                                             Previous owners' propagation notes

After spending time cataloguing the notes and bringing some semblance of order to the pages of plant lists, stories and lessons started to emerge.  One thing was very clear – the previous owners were rhododendron devotees, growing at least a couple of hundred of their favourite cultivars.  As astute readers might have noted, rhododendrons and Victoria’s hot central and northern districts have never had a reputation for being good bedfellows.  The old owners of the garden once lived on Mount Dandenong in Melbourne, which is perhaps the foremost rhododendron-growing region in Australia.  Plant a rhododendron pretty much anywhere on Mount Dandenong and it will thrive.  The Nation Rhododendron Gardens is, after all, in Olinda on Mt Dandenong itself.  With the previous owner’s love of rhododendrons knowing no bounds, their small property overlooking Melbourne soon became too small to quell their rhododendron fever, so they moved to a much larger property.  What they gained in space they lost in climatic suitability; very few of the hundreds of rhododendrons listed in the propagation notes are to be found on the second property today.  You can count the surviving cultivars on one hand, and even then a few look unwell, others terminal.  There is a lesson in this for every gardener – always choose plants that suit your conditions over fighting or trying to change your conditions to grow certain plants.

While attempting to grow rhododendrons in such a location was almost certainly doomed from the beginning, many plants have thrived, even after languishing without any maintenance for several seasons.  The soil on the property is granitic and sandy, so the drainage is quick and sharp.  Any plant belonging to the protea family (Protaceae) in the garden is thriving.  Leucadendron, banskia, adenanthos, grevillea and protea species all exhibit vigour and catch your eye wherever they are found growing amongst the five acres of garden.  So too are other native genera such as eremophila, correa, wattles and gums.  One wattle in particular caught my eye in the Spring of last year. 

                                                          One of the many Proteaceous plants thriving in the garden

Acacia denticulosa is a Western Australian wattle that is listed as rare in the wild.  It is a large shrub with the most profuse and incandescent yellow rod-shaped flowers I have ever seen in a wattle.  It is a stunning plant when in full bloom.  Out of flowering season its leaves are more than enough to carry it as a point of interest all year round.  Known as the Sandpaper Wattle, A. denticulosa has leaves that do, literally, feel like sandpaper.  The foliage is thick, stiff and raspy.  Unfortunately this wattle has proved difficult in cultivation owing to its insistence on nothing short of perfectly sharp drainage.  It grows so well at my friend’s property because their soil is almost exactly similar to the soil in which the Sandpaper Wattle grows naturally.  The propagation notes list it as very easy to propagate but not very adaptable to other soils, which is a shame because it is a plant as beautiful as it is unusual and it deserves to be grown more widely. 

Reading through the notes made by the old owners of this garden was an informative experience.  It was as if peering through a window to the past, and gaining insight on what direction in which to take the garden in the future.  Noting the successes and failures of the listed genera, plants that hailed from environments that were similar to the garden’s location, of course, thrived.  Those that were from environments far different fared less well.  In this is encapsulated one of the central tenets of good horticulture: choose the most suitable plant for the location in which it is to grow. 

Finally, the whole experience of finding the notes and getting a glimpse of the original owners’ efforts reminded me that although we may garden for our entire lives, the pleasures our gardens bring may very well extend beyond our own time working in them.  We are but custodians of a living canvas upon which each successive artist leaves their impression, with accumulated knowledge about a dynamic medium being passed from one custodian to the next.

Until next time, happy gardening.

*This post has also appeared on gardendrum.com, beating a new path to gardening

Uniting the Separation Tree*

Most people serious about gardening will have a favourite part of their local city’s botanical garden.  Perennial borders, sweeping lawns, pools, lakes, conservatories and grottos – botanic gardens the world over are jam-packed with so many areas of interest that choosing only one favourite area is difficult.  As much as I love watching the perennial border in the Royal Botanic Gardens here in Melbourne change with the seasons, my favourite part of the gardens is much more austere.  I should confess here that I am a treeophile.  I simply love trees.  Give me a gnarled, ancient tree over a showy perennial border any day of the week – pretty herbaceous perennials are nought but horticultural tarts compared with the regal majesty of a tree that has seemingly been there forever.

                                                          Colourful perennials at the RBG Melbourne - the flashy tarts of horticulture

  My favourite part of the RBG Melbourne is the Separation Tree, a large River Red Gum (Eucalyptus camaldulensis) that predates the gardens themselves by at least a couple of hundred years.  So-called because it was the tree under which Victoria’s early colonists gathered to celebrate the separation of Victoria from New South Wales in the 1850s, the Separation Tree is older than Melbourne or even Australia itself.  It is tragic that in 2010 a vandal saw it fit to take to the Separation Tree with an axe in a concerted effort to ringbark it, no doubt with the express purpose of killing the tree.  After a year and a half of intense management the tree is looking remarkably well considering the extent of its injuries, and some interesting horticultural trickery is being used in an effort to save this iconic tree from what would otherwise be a certain death.

                                             The Separation Tree after it was attacked (photo: ABC News)

For any plant to grow it needs water, light and nutrients.  The water used in photosynthesis is taken up by plant roots and eventually ends up in leaves, where it plays a crucial part in converting carbon dioxide into carbohydrates before releasing oxygen.  The carbohydrates manufactured in the leaves during photosynthesis are then carried down the cambium of trees to the roots where they play a vital role in forming new roots that help to sustain the tree.  The cambium is the live layer of tissue found underneath a tree’s bark and is crucial in transporting carbohydrates. Ringbarking severs the cambium, effectively stopping these carbohydrates from getting to the roots, and so it is that a ringbarked tree will eventually die. 

Fortunately, the Separation Tree vandal did not manage to sever all of the cambium with their frenzied hacking.  A little live cambium still remains on the tree, after intensive management by RBG staff I might add, but nowhere near enough for the tree to survive on its own.  The initial response to the attack by the RBG staff was to wrap the tree’s extensive wound in hessian, keeping it moist and the tree well watered, and wait to see if any of the remaining parts of the cambium would survive on their own.  Regardless of how much survived after the attack, additional intervention was going to be required if the tree was to survive in the long term.  The unusual and impressive technique of bridge grafting was then employed in an attempt to put the Separation Tree back together again.

                                                                           Detail of bridge grafting being trialled on the Separation Tree

Bridge grafting is a grafting technique that is usually only employed in situations where, through disease, predation or vandalism, a tree has been ringbarked.  It attempts to ‘bridge the gap,’ as it were, above and below the ringbarked area, uniting the damaged cambium and once again allowing nutrients to flow and the tree to survive.  Branches from the damaged tree can be used to form the bridge, or new sapling trees can be planted near the base of the tree and an approach graft attempted to achieve the same outcome.  Both methods have the same aim and differ only in the method of execution – bridging the gap between the cambium void is the ultimate goal.  Both the bridge graft and approach graft methods have been used on the Separation Tree in an attempt that one (or both) of the methods will achieve a successful reunion of the cambium.  Being a year and half since the attack took place the tree is looking remarkably resilient.  One of the first signs of tree stress is a thinning canopy, but the Separation Tree’s canopy still looks quite full despite its extensive injuries.  The next six to twelve months will be crucial in determining if the tree is going to survive, but rest assured the RBG staff and many other national and international experts are monitoring the tree closely, giving it all the help they can.  With the bridge grafting techniques already applied to the tree and ongoing TLC by some of the countries leading arborists, there is still reason to remain optimistic for the tree’s future.  With a little luck and a lot of horticultural ingenuity, here’s hoping the severed halves of the Separation Tree can be united once more.

Happy gardening.

*This post has also appeared on gardendrum.com, beating a new path to gardening