Catherine StewartWhy we must stop mass planting NOW

It’s an emergency. One by one, the toughest garden plants of the past decades are succumbing to newly-discovered, debilitating and often deadly pests and disease. Elm, ash, buxus, roses, horse chestnut, agapanthus, impatiens, clivea, lilly pilly, loropetalum…the list goes on. If you haven’t heard of problems with these plants in your part of the world already, you soon will, as globalisation eventually defeats even the most vigilant biosecurity measures.

Low diversity planting designAND IT IS US – gardeners, garden designers and landscapers and our stupid and destructive preference for mass planting who are to blame.

Every time we plant a hedge, a single-species border or a sweep of identical perennials, we spread and encourage either existing or future pestilence and, in doing so, eventually remove that plant forever from our gardens, our streets, our natural landscapes and eventually our entire country.

Low diversity mass planting designA few weeks ago at the Australian Landscape Conference I heard award-winning Provence-based landscape designer James Basson say:

“I think we do mass planting because we’re not clever enough to do anything else”

Well it’s high noon, and high time we got much, much cleverer.

A history lesson
During my landscape design training years in the early 1990s, there was a strong reaction to the 1980s Decade of the Cottage Garden. Mass planting was now the key to good design, with grouped swathes or hedges of a single plant to provide ‘unity’ and ‘harmony’ in peaceful and beautiful gardens. And it’s still being promoted and preferred as the perfect, quick and easy solution for any garden, by garden design magazines and websites, by nurseries, by gardeners thinking it’s the key to that elusive ‘low maintenance’ garden, and by unimaginative garden designers.

Gordon, SydneyBut these planting styles are leading to gardening disasters worldwide.

Since starting GardenDrum back in late 2011, I’ve become increasingly aware of this creeping, insidious but largely unrecognised problem with our design and planting choices. Although I garden in south-eastern Australia, I read widely about what’s happening in the USA, UK, Europe, New Zealand, South Africa and South-east Asia.

And the news is really bad.

ItalyIn all of those countries, plants that have become highly popular for mass planting over the past few decades for their adaptability, cheap and simple propagation, easy-to-grow habit and strong pest and disease resistance are now succumbing to new problems that are, in some cases, making them completely ungrowable in several countries.

Why is this happening? Why are these previously reliable plants now attracting so many persistent pest and disease predators?
First, the pathogens that are attacking these mass-planting favourites aren’t usually unknown but when we start to supply them with unlimited food all conveniently co-located, it’s akin to erecting an ‘ALL YOU CAN EAT’ neon sign over your garden. Any pest or disease that can attack that plant, if it finds it, will have so much food that it will multiply and spread rapidly. The plant species affected doesn’t have time (ie enough seed-grown generations) to develop resistance. This mass-planting encouragement of pests and diseases is of course, well-known in agricultural food crops, with wheat rusts and potato blight responsible for many famines through history, as a new and more virulent strains of fungal diseases, bacteria or viruses defeat their host plants.

Second, the vast majority of ornamental plants being grown today are clones of a very limited number of parent plants. Vast production nurseries grow tens of thousands of one plant, and often they are all clones of one original parent plant that had the chance mutation which gave us that sought-after new and unique flower colour or form. Today it’s the only economical way to run a plant production nursery, but whether it’s propagation by tissue culture, division or cuttings, the genes of the parent plant are repeated in thousands and thousands of offspring, greatly restricting the genetic diversity of our ornamental garden plants.

Myrtle rust on Waterhousea floribunda (syn. Syzygium floribundum)

Myrtle rust on Waterhousea floribunda (syn. Syzygium floribundum)

I suspect this is an especially critical factor in the rise of deadly fungal diseases, which usually develop in an ‘arm’s race’ style with a single species. The fungus attacks the plant; some plants of the species, because of their genetic diversity, have or develop resistance and survive, the fungus adapts and again debilitates the plant…and so on. But when so many host plants are co-located, and they are likely to be clones without the genetic variation needed for adaptations to arise, they are unable to develop resistance and the fungus increases to the point where it wipes them out.

Third, we transport plants great distances both within our own countries and internationally, carrying pathogens and pests in cut flowers, live plants, seeds, soil and mulch. Although most countries have vigilant biosecurity measures, it is inevitable that things slip through, as happened with myrtle rust entering Australia five or so years ago. I heard of suspicions that this fungal disease, which already threatens to send many Australian native plants extinct by the end of this century, came in on imported cut flowers (but that’s not a proven fact).

What plants are affected?
Potentially anything we mass-plant, whether it’s a tree, shrub or perennial and particularly plants that are grown from cloned vegetative material, which means cultivars rather than species plants. The first well-known ornamental plant mass extinction through pest or disease of which I’m aware was the elm in the mid-20th century. Elm trees had been mass planted as avenue trees all over Europe and the UK and when Dutch elm beetle spread Dutch Elm Disease, the result was fatal for the elms of Europe. There is now only a handful of isolated survivors in the UK, some elms in southern Australia and also New Zealand (although Dutch elm disease arrived there in 2008).
Many of the elms were replaced with horse chestnuts and ash trees, which are now starting to suffer the same fate.

Note that in my descriptions below I am not going to recommend how to control these pests and diseases because that’s not the point of this story.

Chalara dieback on ash tree Photo Jonas Barandun

Chalara dieback on ash tree Photo Jonas Barandun

Chalara dieback in Fraxinus – Ash tree
Chalara dieback of ash is now widespread in Europe and spreading rapidly through the UK. It is terribly sad to think that one of England’s most well-known folk songs ‘The Ash Grove‘ may soon be about an extinct tree as the UK’s 80 million ash trees gradually succumb. Chalara dieback is a fungal disease that probably spread to the UK from Europe via the importation of infected ash nursery stock. New growth wilts and blackens, cankers develop and the canopy gradually dies. There is no cure.

Horse chestnut leaf miner damage

Horse chestnut leaf miner damage

Bleeding canker and leaf miner of Aesculus hippocastanum – horse chestnut
Widely planted to replace elm trees, horse chestnut now struggles against several problems, including a disfiguring and debilitating leaf-mining moth and a number of bacterial pathogens. The first symptom of bleeding canker is yellowing foliage and leaf drop and then a sticky liquid starts oozing from the trunk. The canopy dies and eventually the tree also. Over half of the UK’s trees are now infected.

Box blight or boxwood blight and box tree moth caterpillar on Buxus – English box, boxwood
The renewed popularity of formal gardens in the 1990s saw the popularity of box soar. Soon every garden in Europe, the UK, USA, New Zealand and Australia had a box hedge, box topiary, or both, giving instant structure to a town garden throughout the year as, in a cold climate, box is ‘sempervirens‘ ie evergreen.
Box blight is a newly discovered species of fungus called Cylindrocladium pseudonaviculatum. It was first recorded in Europe in the early 1990s and appeared in New Zealand in 2002 and in the USA in October 2011 and has now spread throughout its eastern states. It primarily affects Buxus sempervirens ‘Suffruticosa’, the small edging box, causing leaf spotting, leaf drop and then whole branches to progressively die back, ruining the look of the hedge. Although it doesn’t (yet) appear to cause significant dieback in other box species like Buxus microphylla, research by the NCSU Extension found that other cultivars can harbour and spread the pathogen. Sarcococca and Pachysandra species are also susceptible.
Box blight rates No2 on the RHS list of disease reports in the UK and gardeners are no longer using box due to the likelihood of the disfiguring disease. It is not yet in Australia but I suspect it will arrive within a few more years. And if this can happen to Buxus sempervirens, then it can (and I predict will) happen Buxus microphyllla soon enough.
The newest woe for the mass-planted box throughout Europe is the box tree moth caterpillar, which comes from Asia and was first recorded in Germany in 2006 and the UK in 2008. It has no natural predators and birds seem to find it unpalatable. It can reproduce 3 times each year and survives very cold winters, so it is now doing serious damage to buxus plantings, as profiled by Helen Yemm in the UK Telegraph in September 2015. The caterpillars are voracious feeders and quickly cause large patches of the hedge to die back.

Box tree moth caterpillar

Box tree moth caterpillar. Photo Didier Descouens

Green strip leaf beetle damage on Syzygium lilly pilly

Paropsides calypso leaf beetle damage on Syzygium lilly pilly

Paropsides calypso leaf-eating beetle on Syzygium australe and cultivars – Lilly Pilly
Lilly pilly, native to Australia, is now the go-to hedging plant all along the eastern coast. Countless cultivars have been developed and most of them are now resistant to the disfiguring pimple psyllid. But a few years ago, something started happening to lilly pillies, particularly Syzygium australe cultivars, and the leaves on many are now so badly eaten, the plants are permanently tattered and torn and become increasingly threadbare.
The culprit is a tiny leaf-eating beetle called Paropsides calypso, identified by Dr Chris Reid, entomologist and leaf beetle expert at the Australian Museum in Sydney – see more below**. (Note that this leaf beetle been incorrectly identified elsewhere as Calomela pallida, the green strip leaf beetle).

Paropsides calypso now infests lilly pilly hedges from north Queensland to Melbourne. And we made this happen – me included – by mass planting lilly pillies.

Mealy bug on agapanthus

Mealy bug on agapanthus

Mealy bug and gall midge in Agapanthus
Can you remember the good ol’ days when agapanthus was the bullet-proof choice for every warm temperate garden? There were nurseries in the 1980s devoted to pumping out mainly this one plant during its peak popularity. It’s still widely planted around the world but there are now new pestilences arising.
In Australia where once these plants survived our long heatwaves, those in full sun now get badly burnt. Many plants show deformed, pale, thin and wavy leaves. The culprit is a mealy bug that infests agapanthus plants and weakens the leaves so that they can’t translocate enough water during hot and dry periods. And the mealy bugs are impossible to eradicate.
In the UK, it’s the agapanthus gall midge that’s doing the damage, causing flower buds to abort.

Agapanthus severely affected by gall midge. Photo RHS

Agapanthus severely affected by gall midge. Photo RHS

Rose Rosette Disease (RRD) on Roses
Roses are a one of the world’s favourite plants. Although gardens throughout history have had both species or new hybrid roses on show, they were always specimen plants in limited number…then the mass-planting rose arrived on the scene and slowly but surely, the ground rules changed. Rose Rosette Disease (RRD) is sweeping through the USA, spread by a tiny mite, and no rose is immune. RRD causes ‘witch’s broom’ new growth, red leaves, oddly thick growth, mottled flowers, reduced winter tolerance and plant death after 2-3 years. RRD has already destroyed significant rose collections in eastern USA, including in the Brooklyn Botanic Garden, and has spread to Canada. Even the highly disease-resistant ‘Knockout’ roses succumb.

Rose Rosette Disease

Rose Rosette Disease

Impatiens - photo Alison Aplin

A lovely potful of cheerful Impatiens – photo Alison Aplin

Downy mildew on Impatiens
These cheery little short-lived perennial plants brightened many gardens from temperate to tropical zones until a few years ago. Tried to buy one lately in the USA or Australia? Chances are you’ll only find New Guinea hybrid impatiens plants on offer. A virulent downy mildew, Plasmopara obducens, attacks Impatiens walleriana, causing stunting, leaf yellowing and leaf fall and eventual plant death. It was first recorded in Australia in 2006 and in the USA in 2011.
In the USA it is now spreading to other ornamentals that have been mass planted instead, like Gynura and also basil cultivars. The New Guinea impatiens, Impatiens hawkerii is resistant but, with it now being mass planted instead, how long before a new mildew arrives to defeat it?

Cypress canker Photo Gloria Ballard from her excellent blog at The Garden Bench

Dieback on leylandii cypress from Cypress Canker. Photo with the kind permission of Gloria Ballard from her excellent Q&A blog at The Garden Bench

Cypress bark weevil, cypress canker and cypress aphid on xCuprocyparis leylandii ‘Leighton Green’
For some, this pest and its often accompanying disease can’t spread fast enough to rid suburbia of inappropriately-planted ‘monster hedges’ of Leighton Green cypress. Symptoms of both the bark weevil and the Seiridium canker fungal disease (which can enters the tree through damaged bark) are browning and then dieback through the canopy. Trees that are stressed through drought are more susceptible, especially when it’s followed by warm and humid weather. Monterey cypress (Cupressus macrocarpa) is also infected. Cypress canker is becoming more widespread in the USA and Australia.
In the UK cypress aphid is also responsible for widespread browning and dieback on Leighton Green hedges, especially during the spring growth season. As climate change reduces the number of severe winters, entomologists expect that cypress aphid infestations will increase throughout southern England.

I’m thinking that you are now thoroughly depressed. So what’s the solution? How do we have beautiful and structured gardens without mass plantings? My thoughts to come next week…

** Dr Reid says: “Paropsides calypso has spread in the last 10 years from NE NSW where it is native and only seems to feed on Syzygium australe. It first turned up in Sydney about 5 years ago and probably poor quarantine between nurseries has helped its spread. Its eggs are laid on leaves or leaf buds, and the green larvae are relatively solitary (not clustering). Pupation is IN SOIL at the base of the plant. There are possibly 2 generations – a long winter one and short midsummer one, or maybe just one generation. It’s now known as far south as Victoria. The adults and larvae both feed on leaves and completely strip hedges/bushes.”

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Catherine Stewart

About Catherine Stewart

Award-winning garden journalist, blogger and photographer; writer for garden magazines and co-author of 'Waterwise Gardening'; landscape designer turned landscape design judge and critic; compulsive networker and lover of generally putting fingers in lots of pies. Particularly mud pies. Creator, curator and editor of GardenDrum. Sydney, NSW.

34 thoughts on “Why we must stop mass planting NOW

  1. Really useful article Catherine! Personally, if I need to use volumes in the gardens I design, I put in the same mass different varieties of the same species (ex. japanese and dutch buxus, or Acmaena Smithii ‘Green Screen’ with ‘Fire Screen’): growing different types of plants together confuses pests that normally target a specific type of plant.
    Also, I like the difference and the similarity that I can get with this trick 🙂

    • Thanks for sharing your way of incorporating both repetition and diversity into a design Carlo. I will certainly be talking more about it in my follow-up post.

  2. helen mckerral on said:

    Very interesting, Catherine. I have to force myself to plant more than one of each because, like all dead keen plant folk, I am hopeless in a plant nursery and find it very hard not to buy every sparkly new thing that catches my eye! Now, though, I try to buy at least three of the same plant (if they are small-growing) and, in a way that’s related to Carlos’, dot them about my garden, which is an admittedly eclectic – but certainly diverse! – grab-bag.

    In a natural Oz landscape, there’s plenty of mass “planting” and repetition (think of stringybark forest – in my local area the overstorey is primarily two species of Eucalypt) – but that mass is broken up by other plants that are equally represented: the common understorey species shrubs in my neighborhood are Pultenaea daphnoides and Bursaria spinosa, amongst others. Even more striking in their apparent uniformity are our outback plains of saltbush, or spinifex. But of course, as you suggest, there’s enormous genetic diversity within each of these populations that makes them resistant to attack.

    So you could in theory have a mass-planted garden, as long as the overall diversity of genetic material is high (same species but seed-grown, not clones) and the number of species within that garden is also high.

    Perhaps this lack of diversity in gardens today is linked not just to the widespread availability of a relatively small number of fashionable clones, but also to the demise of the keen gardener (who enjoys the search for rare and unusual plants) and to the smaller size of the average garden, which must reduce diversity.

    • Very interesting observations there Helen, about natural landscapes with a dominant species. I think too that in these landscapes, the plants are rarely so tightly packed as they are in a mass planted garden, where each is so close to the other that their roots often self-graft and become continuous. And yes, I think you’re right about the demise of the keen gardener contributing to less diverse gardens. If only gardening knowledge could be elevated to celebrity status like the ability to cook and plate-up a meal!

      • helen mckerral on said:

        Well, we do have our gardening celebrities such as the Jamie Duries and, ahem, Costa! But you’re right: the kinds of speakers that so inspired you at the landscape conference don’t get the same kind of profile.

  3. Sonny on said:

    Thanks for the article. It makes me feel somewhat better about my slightly ‘randomised’ garden, which a visiting garden designer was somewhat aghast with.

    Although I have a couple of lillipillies and a highly underperforming lemon myrtle (in Melbourne), I have a lot of ‘redundancy’ so my garden wouldn’t be too impacted if they died. I’ve also retained a number of trees/shrubs that have grown by themselves and become a legitimate part of the garden.

    Looking forward to learning what action we can take.

  4. Thank you for this – I find the “typical” mass-planted gardens that have elevated some landscapers to celebrity status to be utterly boring and lifeless, quite apart from the fact they are restricting biodiversity.
    However, much as I’d like to, I’m not so sure they can be blamed for the spread of mass diseases; many of the fungal infections affecting UK plants have been imported from the US and affect trees in natural mixed woodlands too.

    • Of course designers who promote mass plantings in their formal gardens are not solely to blame, but I think they must take a share of it, even though you could argue that they only became successful because enough people wanted to buy their garden style. Mass planting is not restricted to formal gardens, and I would have shown that, if a search through my thousands of photos had turned up any mass-planted informal gardens. And yes, natural woodlands are affected too but these diseases seem to have arrived there from ornamental plants, not the other way around. Most of the disease problems in the UK have actually arrived there from Europe, being able to spread more easily across a land mass, and then make the short jump across the Channel with the less stringent biosecurity within the Eurozone. The timings for boxwood blight discoveries show that it was known in Europe and the UK 15 years before the USA.

  5. Robert Prince on said:

    Great article Catherine, I have shared with AIPH and will be discussing at Congress in Milan next week. As you state problem is “global”

    • Thanks Robert. It would be great to see the nursery industry driving a change among gardeners and landscape designers from relying on too narrow a group of plants.

  6. mattb325 on said:

    Thankyou for posting this article; I have long being opposed to monocultures in gardens. It becomes even more problematic when so many gardens all end up using the same plants for these mass plantings…how often do you walk through any Sydney street only to see the same murraya, buxus, trachelospermum, agapanthus, clivea, syzigium, plumeria (and so on) repeated over and over.
    The other big issue (which is tied into monocultures) that causes these diseases is gardeners selecting plants which, while they perform ok in a warmer climate, really only ‘thrive’ in a cooler climate from theirs: eg leylandii in warm coastal areas…while these plants will do fine for many years, the pathogens really do build up, become more aggressive and resistant and then are easily spread to cooler climate areas with devastating consequences….

    • Thanks Matt – you forgot one Sydney ‘everywhere’ plant that’s yet to see a debilitating pest arise but I’m sure it will – Viburnum odoratissimum. And recently in northern Sydney I walked past a Murraya hedge and disturbed a cloud of tiny brown moth-like critters I haven’t seen before. The leaves were sticky with honey dew, so now doubt a sap-sucking pest moving in.

  7. Thought provoking Catherine. As well as providing a 24-hour diner for pests and diseases, mass planting also stresses plants. Prolonged droughts, off-the-record heatwaves and water restrictions haven’t helped either – indeed I think these are the primary trigger. Close planting as is done in hedges and small heavily ‘designed’ gardens means root competition for nutrients and water. Constant pruning stresses plants further. Stressed plants get problems and need to be seen as the plant’s plea for help – give me food and water and a bit of space to grow.

    • That’s a very good point you make about the constant pruning required in a formal garden stressing plants and contributing to their being more disease-prone. I hadn’t really considered that and I’m sure you’re right.

    • I agree, there are a whole host of issues around what and how we plant and garden, which stress plants and make them susceptible to pests and diseases, where an unstressed plant would fight them off. In almost all suburban gardens, long hedges will have different microclimates at either end and yet we plant the same species in the full sun at one end and under next door’s tree at the other. I’m on my mission to ensure we plant more suitable species for each microclimate; I think it will solve a multitude of problems. Great article, Catherine.

  8. The sustainable garden has been overlooked for too long. The consensus of opinion of landscape designers and architects at the Landscape Designer’s Conference was, once again this year, in favour of the sustainable landscape. Here biodiversity in all of its forms is encouraged and moves well away from the mass planting objective used by so many landscapers.
    Sustainable landscaping is garden design of the future – there needs to be a big drive to further this quest in support of the environment.
    Alison Aplin
    Timandra Design & Landscaping
    2014 Landscaping Vic ‘The Sustainable Landscape’ Award Winner

  9. Great article, Cath! Here’s another quote from what James and Helen Basson told us at the Australian Landscape Conference last month. ‘Complexity is the only long-term solution for sustainable planting design. Put in plants that compete, and plants that get together. Then if a plant is attacked there will be something to replace it.’

  10. Very thought provoking. Monoculture plantings are often devoid of imagination too, and take take away the joy of being an impulsive and acquisitive gardener.
    Liz Chappell

  11. Thanks Catherine and all. I blame social media a bit too. We find ourselves in such a visual culture, where whatever photographs well becomes the dominant idea. the clean lines of formal monocultures work well as easily-readable little shareable shots on pinterest and houzz and those images influence what people desire. Perhaps the dullness of the formal garden is like the white wall homogeneity of interiors shown on Domain, or those doughnut-decorated milkshakes on instagram – all about the picture. Of course it doesn’t matter what’s to blame, losing all these plants is just horrible.

  12. A great article Catherine and I’ll start by saying that I share some of your concerns, despite being a nurseryman guilty of growing great swathes of single clones over here in the UK. However, the problem is more complex than you’re making out and I’ll give a few examples I know a little about to demonstrate that…
    Here in the UK we have indeed lost our Elm population, but not because we decided to plant Elm en-masse as street trees a few generations ago. At one time much of Britain was covered in Elm woodland and some of the species reproduce from suckers rather than seed, so genetic variability has been limited for tens of thousands of years, making the tree susceptible to attack. In fact, the historic pollen record suggests our Elm population has been periodically devastated throughout the millennia. We still have the tree in our hedgerows (it survives to a certain girth and then succumbs) and, given a few hundred years, it would probably establish again. Of course, we as individuals are impatient to wait that long. The point is, sometimes these issues look ‘Big’ to us because we view them from our limited perspective, taking a near-sighted timescale. That is not to demean the scale of the problem – Elm was my favourite tree as a child, none of my children have ever seen one!
    The Chalara and Ash story is also a bit more complicated. It is probably a mutation of a common pathogen of Asian Ash and has been making its way East for some decades now. It was indeed brought across the water on nursery stock, but, independent of that, it has also crossed the water on the air. Ash reproduces by seed very readily and if the UK were a ‘Natural’ landscape we would eventually see resistance showing through: but we are a managed landscape and we won’t tolerate the wait that would involve. Personally I think this is an example of how the inter-continental movement of plants can allow a harmless pathogen mutation in one part of the world to become a devastating problem somewhere else in the world, but it’s certainly not a symptom of mono-crop planting of Ash trees.
    Box blight is indeed rampaging around the UK. It’s worse in wet summers, we’ve had a few of those recently and are likely to get more if global warming hits this maritime climate as you’d expect it to. In addition, we nursery men and our gardening public each have fewer fungicides at our disposal than we used to have. And again, the globalisation of plants as a commodity moved the pathogen around quickly and efficiently. I think these are the real factors in the case of Box blight, not the mass planting of the species. Since the Renaissance period, when the new thinkers of the day tried to work out what ‘Paradise’ would have looked like and concluded it would have the strong geometric form they had recently re-discovered in mathematics, box has been used in vast numbers to give geometric line to gardens. These vast quantities make its collapse visible when it happens, but I’m not so sure it is the cause of the collapse.
    My point is, we do indeed have a problem with plant health and we need to treat it seriously. But it’s not as simple as mass planting: inter-continental movement of plants, climate change, a reducing arsenal of chemicals all play a part, in my view a greater part than the mass planting effect.

    • Thanks for your many interesting observations Tim. Although I agree with some of what you say, the sheer volume of mass plantings in the 21st century far, far outstrips anything that went on in previous centuries or even decades. Most home gardens didn’t have any designed plantings until 30-40 years ago, instead being a pleasing but haphazard mix of a much wider range of plants. So while box hedges were a historical part of the English garden, they were grown on large estates by the wealthy few who could afford to maintain them, and miles apart from each other. Since we have been able to clip in an hour with a powered hedgetrimmer what used to take hours if not days, this garden style of the rich is now within the reach of everyone. As box hedges still seem to carry that ‘I’m rich’ cachet, they are now in hundreds of thousands of gardens that I doubt would have had any pre 1990. In my part of Australia, I had never even seen a buxus plant until I was 25, and now 80% of the houses around me have a box hedge. I also disagree that fungicides should ever be an answer to controlling fungal diseases in a mass planted species. Once you need fungicides, you’ve already got a fundamental problem.
      As an occasional visitor to the UK, I also saw the great changes in street and park plantings that accompanied the disappearance of the elms. Of course horse chestnuts were around pre 1990 but I was astonished at how a decade later they were suddenly everywhere, until it was explained to me that they were the tree of choice for elm replacement.
      So although I agree that the other factors both you and I mention are part of the whole story, I still hold that it’s mass planting that is the main cause of the problem.

  13. Clare bell on said:

    Hello Catherine
    Your article is very timely and really highlights the problems that I now see and read about the increasing pest and diseases with limited species gardens worldwide, especially in the last five years.
    This is not just for Australia as I also these problems highlighted in the UK Royal Horticultural Society magazines.
    I see this in a positive light that this is an avenue for Qualified Horticulturalists and Landscapers to step up and be recognised as guardians and experts in integrated disease management of these formal,existing gardens so highly prized in some of our Sydney suburbs.
    There is always hope for future garden designs for the Landscape Architects and Landscape Designers with your excellent article in mind!
    Meanwhile, I am a firm believer in garden diversity, as in my own Confetti Gardens Mt.Colah, I really can appreciate the spendour of a uniform garden but am disturbed that so many of the garden maintenance companies do not go beyond clipping and mowing and probably will never read this article!

  14. Ellinor on said:

    A very simple explanation to a much more complex problem – this runs deeper than mass planting. Don’t forget that the vast majority of gardeners do not engage the servicè of garden designers and plant instead a large variety of flowering pants of their choice. Gardens are created everywhere and not only in a narrow strip of affluent suburbs.

    • While you’re right that most gardeners don’t employ a landscape designer, most gardens are not planted or maintained by what you or I might call a ‘gardener’ either. Plants are bought – usually from a ‘box store’ nursery with a very limited range of plants – and planted in a way that’s aspirational rather than inspirational ie the garden is made that follows a latest garden fashion, or garden design ideas that look wealthy, and from plants that the non-gardener has seen around and recognises. The range of plants in most 21st century gardens, and even a well-stocked quality nursery, is tiny compared to what it was 30 or more years ago.

  15. I am planning to plant a hedgerow in my new garden in Wanaka, New Zealand with a lot of diversity in the plantings for everything from fruits to autumn colour, flowers, evergreens and deciduous. I was amazed at the diversity of birds and animals I saw in an English hedgerow. Would welcome any suggestions about this.

  16. sandra on said:

    Great article Catherine, really interesting. I allowed a small box hedge to be foisted on me by a landscaper, much against my better judgement (and he wanted more of them) … 2 years ago one end began succumbing to box blight which, because it is only a small hedge, I decided to try and fight.

    This year the affected section is coming back into leaf and looks healthy, if still needing a bit more growth to fill in. When I noticed die-back sections I cut them out, sprinkling cinnamon liberally on the cuts and surrounding foliage. I regularly sprayed the hedge with seaweed fertiliser, as well as watering the roots with the mix and now that spring growth has started again will do that again, continuing through this summer.

    • Oh dear. Thanks Sandra, I had wondered how entrenched it had become in NZ. What does the cinnamon do?

      • sandra on said:

        It is, apparently, a natural fungicide. People in my orchid club use it as such and I figured it couldn’t hurt. I’m in a more humid part of NZ and it has been the end of the hedge that gets a bit closed in over summer that’s been affected. I have seen plenty of box in this area that’s been hit and plenty has been taken out.

  17. Sonny on said:

    Where can I find part 2 of this article, mentioned above? Looking forward to reading.

  18. Heather on said:

    Hi, I can’t find your follow up piece and now that I’m depressed I would really like to read how to plant a structured garden without mass plantings.

  19. PJ on said:

    Mass planting has been undertaken in gardens since the beginning of time because uniformity is one of the keys to harmony. Would you, for instance, like to go back to street planting in Australia, as was conducted in the 1970s, where every tree in the street was a different species, so creating a visual mess? Surely not! But yes, there does have to be a greater diversity of genetics and species mass marketed.

    • Yes uniformity can create harmony but if the cost is losing that plant forever to ornamental horticulture because of rampant plant pathogens, then we will just have to rethink how we create harmony. Re the loss of monocultural avenue plantings, I think that came about because local governments decided, unwisely, to give residents more autonomy about what was planted outside their homes thinking that this would make them then invest more in the tree’s care. However, as we are already losing avenue plantings like English elms, claret ash (now all removed from Canberra’s streets) and ash trees throughout Europe, I think we have to accept that the days of beautiful avenues of a single species are no longer wise or even possible long term.

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