In any country you will find natural vegetation invaded by weeds, from rampaging vines to promiscuous and prolifically self-seeding annuals, and even trees that envelop all below them. But as a recent arrival in a new/old garden, I am astonished at how many plants are still grown and sold as acceptable ornamental garden plants that are a nightmare for anyone living over the other side of the fence.
Often it’s ignorance, sometimes just couldn’t-care-less, and even occasionally malice that sees plants that should never, EVER be planted in suburban gardens causing grief for every neighbour. What horrifies me is that these plants are still sold and promoted as suitable for home gardens, even while we’re seeing residential land sizes and garden areas rapidly diminish.
The garden I’ve moved too was previously ‘tended’ by an older widow. As my elderly neighbour Beryl commented with classic Aussie understatement, while standing sympathetically at my shoulder and looking at the butchered shrubs, starving grass and proliferation of weedy vines:
“Yes, well…Sonja. She was no gardener, really, was she.”
While many weeds are spread by birds, or wind or water, there are also many weeds and highly invasive plants that are spread by ignorant people buying and planting them. I have had many of the nightmare plants listed below invading either this, or previous gardens. In each case I have laboured and struggled to rid my garden of the plant, cursing at every attempt the madman or woman who put them in the ground in the first place.
Other plants are on the hate list because I know a GardenDrum author who has had a similar depressing experience either trying to deal with, or remove them from her/his own garden. And one is on the hate list, not because of its weediness but because of its special stench, which I can honestly say is just as appalling to live next door to when it’s planted en masse.
And many of them are still for sale in nurseries, ready to be bought, brought home and then released on an unsuspecting neighbour. To me, these plants are even more infuriating violators of an otherwise peaceful existence in this beautiful part of the world than the Cujo-sized dog across the valley that barks in the night, or the neighbour’s cat that digs up my newly-planted herbs, or even the lazy postie who deems it acceptable to create deeper and deeper motorcycle ruts along the soggy grass footpath instead of using the road.
They must and will die.
I know someone will quote at me that
“a weed is only a plant out of place”.
I say there is no place in home cultivation, except perhaps in a pot in an alarmed and guarded vault, that these plants are NOT out of place.
English ivy, Hedera helix
English ivy comes first as I hate it the most.
I’m now in my third garden in 20 years, and I’m confronted yet again with the same old enemy, English ivy. (Maybe it’s my Scottish genes?) Often planted to ‘soften the bare fence’, it rapidly spreads by underground stolons and smothers everything in its path. The leaves have such a waxy cuticle that it shrugs off a spray with conventional glyphosate poisoning with ease. It’s clinging feet can scale fences, houses and trees, often causing death to the tree and permanent damage to brickwork and render. Old ivy will become arborescent, which means it develops a different, more woody growth habit and even larger leaves.
Often blamed for causing allergic hayfever when its disturbed, I think it’s actually the accumulated dust of many years that’s built up, as its dense and waxy foliage acts like an umbrella even in prolonged rain. I do know that spending any time near it starts me sneezing and wheezing.
Eradicating ivy: From my experience, the best removal treatment is stem-scraping, or frilling in conjunction with full-strength glyphosate. Don’t try to get rid of ivy by spraying its leaves or cutting it down and painting herbicide on its stumps. It may feel good at the time to quickly remove all that biomass but a slow and relentless offence will prove much more successful.
Using a sharp knife, (or a potato peeler on small, soft stems, and a hammer and sharp chisel on old, tough ones), cut or scrape a 25-50mm (1-2 inch) long by 5-10mm (¼-½ inch) wide section of the bark back to revel the green cambium layer beneath. This produces a thin curl or ‘frill’ of bark, giving the technique its name. Don’t ringbark the stem – you need to get really nasty here and keep it alive while you kill it slowly. By dribbling undiluted herbicide on this exposed plant tissue (I use an old squeeze sauce bottle with a twist top), the ivy will translocate it around the plant, even to the roots. It may take several weeks for you to start to see dying foliage. As the browned leaves fall, you’ll be able to get to the tangle of stems below and you’ll also see where you need follow-up treatments on the still-green areas that you’ve missed, or on another part of a thicker stem.
Wisteria spp (any kind)
Wisteria is like a disarmingly charming and good looking friend who turns out to be your basic psychotic nightmare. When it’s dripping with scented purple or white blooms, it’s divine. It looks so cottagy, so pretty, so fairy-tale.
But as the flowers fall, its true nature is revealed – it is really a huge and malevolent serpent that will loop its way underground to appear many metres away from where it started, ready to coil about and then squeeze the lifeblood out of every living thing in its path.
It will bring down the most strongly built garden arch or pergola. While you are inside making a cup of tea, it will slither through the fence, and start to twist its way up your neighbour’s trees, and twine through their screen door and around their downpipes – and perhaps them too if they sit still too long.
There is no species of wisteria that belongs in a suburban-sized garden, whether it’s from China, Japan or eastern USA.
Eradicating wisteria: I am trying the same scrape/frill method on the wisteria but, as it was already a little late in the season for this deciduous vine, it has been with mixed success as it slid into winter dormancy. However there are many dry, dead stems now, so I’m hopeful that, come the spring, I can finish it off.
No it’s not all ‘jasmines’ that incur my wrath. It’s the highly fragrant common jasmine Jasminum polyanthum that’s super invasive and very difficult to control, let alone eradicate.
People who buy jasmine rarely plant it on an internal structure. Oh no, they want to share its heady fragrance with their neighbours, so it is invariably planted against a dividing fence. By the end of its first year it’s a white froth at the top of the fence. By the second, its found its way through and under the fence. By the third year, if unchecked, it is tunnelling away and then popping up like a cheeky Caddyshack gopher, metres away from where it started. After more than five years, it can be found up to 15 metres from where it began. I know!
Eradicating jasmine: it responds very quickly to the scrape and paint ‘frilling’ method.
Golden or running bamboo, Phyllostachys aurea
Many Australian local government areas now have a policy about running golden bamboo, Phyllostachys aurea, requiring it to be kept at least 3 metres (10 ft) away from a side boundary. Planted by very selfish people with a privacy obsession, golden bamboo is a devil that will quickly take total possession of your garden. It forms impenetrably dense thickets and its vigorous rhizomes fan out like invading army, marching underground across 20 metres with ease. It creates both a fire hazard and a haven for snakes and rats.
Thankfully you will no longer find this invasive thug for sale at most reputable bamboo nurseries in Australia, although in cooler climates it’s still sold and it’s still widely available in the US – one US nursery even says, in classic understatement, that
“Phyllostachys aurea can be an aggressive spreader in hot climates, where care must be used in its placement.”
You don’t say.
However many counties in eastern US states and California now have running bamboo bans or set-back laws.
Eradicating running bamboo: You can try cutting and glyphosate painting every cane but I found that just makes it angry. Patient, laborious digging-up of smaller clumps and runners will defeat it in the end. Start where you see the most distant culms and gradually work your way inwards. For larger clumps, it will require heavy machinery – followed up by patient and laborious digging-up.
Leyland cypress, ×Cuprocyparis leylandii, syn ×Cupressocyparis leylandii
While it’s true that any tree planted too close to a boundary can loom over the neighbours’ yards, the much-hated Leyland cypress hybrids are, I think, the worst. And when you’ve got a whole hedge of them along a boundary, they are a nightmare. Their thick foliage allows no light at all, their dense and greedy roots fill the soil around them and, because many people have this strange and deluded fancy that conifers might be very tall but conveniently stay very skinny, they are often planted much closer to a fence than any flowering tree or shrub. And usually on the planter’s shady side so the cypress won’t make their house dark, forgetting or deliberately ignoring that obvious fact that their shady side is their neighbour’s sunny side.
News flash – conifers that look narrow in a pot do NOT stay skinny. Their trunk expands just like any other large tree.
Dealing with Leyland cypress: you can wish cypress canker or beetle down upon it which will hasten its removal but that’s only a remote possibility. And unfortunately pruning back to a fence line is a poor solution as conifers do not regenerate from old wood, so you’re left with a super ugly tree that looks scalped on one side.
In the UK the Anti-Social Behaviour Act 2003 gives local authorities the power to require high hedges like Leyland cypress to be trimmed where they exclude solar access for neighbours. In Australia, in NSW and Queensland there are tree laws with sections addressing obstruction of sunlight or loss of views from a tree on adjoining land, however in other states you must rely on common law.
Vinca major and Vinca minor, periwinkle
Now covering vast areas of southern Australia and also California and warmer states in eastern USA, parts of South America and also northern New Zealand, especially along river banks, vinca looks like a wonderful shade tolerant, well-behaved groundcover. Until it isn’t. Often planted by gardeners (and here’s the irony) as a weed control, in warm climates vinca will soon be totally out of control.
Eradicating vinca: Its waxy leaf defies herbicide sprays and incomplete removal will see it quickly re-sprout from any stem nodes left in the soil. If your neighbour has it and the boundary fence is not armoured steel that extends 600mm (2 ft) down into the soil, soon you will have it too. If you want to use chemical rather than mechanical control, 360g/100li glyphosate (plus a penetrant) sprayed at the peak of summer growth will have the most effect (see University of Queensland trials).
Juglans nigra (black walnut), Casuarina spp (sheoak), Pinus spp (pine)
Just like the sociopath, these plants have a complete disregard for the rights of others and will work hard to suppress the growth of other plants in their root zones. Except in the case of black walnut which has roots that exude juglone, the scientific research isn’t entirely conclusive about whether this is by exuding chemicals from their roots or the decomposing fallen leaves or if it’s really more a physical thing. In its natural habitat, Casuarina often occurs as monotypic stands which sure looks like something nasty is going on.
The juglone in black walnut acts as a respiratory inhibitor in some plants, particularly apples, tomatoes, pines and birch trees. Nearby plants start to yellow and wilt.
But what is certain is if your neighbour has planted casuarina or pines along the boundary, the constant carpet of needle foliage will smother any plants beneath it. That’s if you can even get a plant into the ground in the first place, as the thickly matted root zone will also defy your attempts to dig and plant anything.
Dealing with allelopaths: If you’ve got black walnut trees just over the fence, don’t attempt a copse of silver birches or a vegie garden in its root zone. And if the tree produces walnuts and doesn’t seem to be a black walnut, don’t relax, as many productive walnut trees can also be grafted on to black walnut roots. Make sure you collect and dispose of (thoughtfully) the walnut shells of dropped fruit as they too contain juglone. You can find plants tolerant of juglone HERE.
As for casuarina needles…hmm. Perhaps collecting them and using them elsewhere as a weed-deterring mulch could be useful? Maybe heaped on top of a Vinca somewhere.
English box, Buxus sempervirens
Have you ever been out on a walk through suburban streets and suddenly been struck by the overwhelming stink of tom cat urine? It comes as a surprise, when these days most suburban cats are desexed. But it’s more likely tom cats covered in a leafy disguise aka English box or boxwood. How people tolerate this vile stench in their own gardens is beyond me, but planting a hedge of it close to the fence and right near a place that your neighbours like to sit outdoors is just plain bloody-minded.
I can’t decide whether it’s worse in colder weather or worse in warmer sunshine but, to me, the stink is quite nauseating. The groundcover conifer Juniperus sabina has the same foetid smell.
Combatting plant stink: as you can’t really remove your neighbours’ plants without argument, try planting pleasantly aromatic plants where you sit. As flowers don’t last long enough and are rarer in winter when it often seems worse, I’d choose aromatic foliage. Lavender is strong enough to overcome most bad smells. You can also try an outdoor citronella candle.
And I read that a boxwood hedge can even ruin a house sale if you’ve put it near your front door!