Why are Agapanthus so controversial?
Agapanthus flower in bloom
Easily, the most divisive plants in the Blue Mountains local community are Agapanthus, or "aggies" as we call them. As a horticulturist, I have never seen as much division or uproar about a plant in my life. Personally, I have witnessed heated exchanges in the street between residents over their purple verge plantings. I’ve seen neighbors sneaking around in the dead of night armed with secateurs, beheading blooms before they get the chance to unfurl their petals. Two weeks ago, in a picturesque laneway lined with agapanthus, I was bowled over by a resident who, without a 'hello,' brashly spat out, “I’ll have you note that my house is the only house in the lane without agapanthus flowers!” as she hurried by me. And this is just what I’ve experienced in person; social media is a constant storm of agapanthus discourse!
So, for a plant that’s only listed as a Control Measure (lowest priority) weed on the Blue Mountains City Council weed list, why so much hate? And why are people so enraged by them? There are so many state, regional, and local priority weeds that most people wouldn’t even know the name of, let alone what they look like. But the Agapanthus has become the poster child for intense hate. A symbol for all environmental issues in the area? An easy outlet for people’s frustrations with life in general? It is unclear... I want to examine how and why the disdain for this pretty ornamental is justified.
Native to southern Africa in the Cape Province and Natal, South Africa. It’s unknown when exactly Agapanthus was first introduced to Australia, but the earliest mention of the species in Australia comes from South Australia in the 1970s.
Over the past 50 years, Agapanthus has naturalized in parts of Australia, including Southwest Western Australia, Victoria, temperate regions of South Australia, and the Blue Mountains Region of NSW. When a plant naturalizes, it means that a non-native/exotic plant that is introduced to a new ecosystem can reproduce and start a new population with ease and continue to spread through that ecosystem. For the record, Agapanthus (Agapanthus praecox subsp. orientalis) is regarded as a significant environmental weed in Victoria and is also deemed to be a potential environmental weed in New South Wales, Tasmania, South Australia, and Western Australia (As of Feb 2024).
Agapanthus flower head
Why are there so many in the Blue Mountains area?
Erosion Control
A reason Agapanthus has become so prevalent in the Blue Mountains area is because of its ability to control soil erosion. Living with steep hillsides and escarpments, Agapanthus has made an excellent erosion control plant. Its strong, fleshy rhizomes and root systems mat together, holding back loose topsoils, and its ability to grow and spread quickly has made it an ideal candidate for the job.
Fire Resistant
In the past, they have been (potentially incorrectly) suggested as a fire-retardant plant. They clump together and have very fleshy waxy leaves, thought to stop fire in its tracks. But realistically, this only works when we are talking about grassland fires. Yes, when a grass fire is met with a thick swathe of Agapanthus, the fire will find it hard to make its way through them. Living in one of Australia’s most bushfire-prone areas, their title as fire-resistant or retardant has made them enticing to gardeners and homeowners of the Blue Mountains in years gone by. A major plot hole is that our fires aren’t grass fires; they are full-blown bushfires with the voracity to leap between the canopies of trees with great ease, rendering the case for Agapanthus being fire-resistant here fairly null and void in our area.
Exotic Charm
The obvious reason Agapanthus is so prevalent is because of its exotic charm and beauty when in bloom. Throughout the upper Blue Mountains, summer means a sea of purple and white that even the most visceral Agapanthus opponent could agree looks rather magnificent. Out of bloom, the deep green strappy plant keeps itself fairly neat and tidy with little to no effort at all, even through times of drought and heat stress.
© Reiner Richter, Agapanthus in Australian bushland
The alarming issues with Agapanthus.
What makes them so bad… It boils down to the natural environment. We have a very special set of ecosystems within the national park, and the threat of a competitive species like the Agapanthus is detrimental to the ongoing natural beauty of the world heritage-listed site.
Though the Agapanthus is an exotic plant, it is very well adapted to our climate and soils. It is an aggressive spreader, some would say a super-spreader (sorry, are we over COVID jokes?). Their rhizome root system constantly builds on itself, spreading and sending new clumps of foliage out at every chance it has. Beyond its root system, it spreads readily by seed, which can make its way into waterways and spread deep into the national park, eventually washing onto banks and starting new populations in locations we can only dream of. The biggest issue with this is the fact that they easily outcompete local flora, smothering the ground and preventing endemic natives from establishing as they naturally would. In particular, the Blue Mountains has a number of endangered plant species that, due to the park's unique ecosystems, if the Agapanthus takes hold, it is likely to spell disaster for a number of these species. This has a trickle-down effect on native wildlife that may feed off fruits and seeds of endemic plants that Agapanthus smothers out. Agapanthus is also not a food source for wildlife.
How To Remove Agapanthus?
Haha… get digging. No, really, get digging! By far, the best method to remove them is by digging them up.
Use a mattock to leverage them out of the ground. It will be incredibly hard work but rewarding. Be diligent in removing all of their root systems. If a small piece of their rhizome root is left in the soil, your Agapanthus will reshoot once more. For large swathes of Agapanthus, it may be more cost-effective to hire someone to remove them with machinery. This will save time and your back.
You can kill them with chemicals, but not very effectively, and I personally do not recommend this.
Spraying the leaves with triclopyr, mixed with a surfactant, which helps to break down their waxy leaf coating and absorb the chemical into the plant's system. You'll need to diligently reapply this spray every month or so until all your plants have turned to mush and are no longer reshooting.
The biggest issue with triclopyr is that it can live in the soil for a long time after you spray. This is detrimental to the long-term health of your soil and, in turn, the health of your garden.
I think we have our answer as to why Agapanthus are so controversial…
The reason Agapanthus is so detested is a combination of the harmful environmental impacts it has on our country's natural ecosystems and its bombproof resilience, which renders homeowners, gardeners, and environmentalists virtually powerless against its continual spread. If you're an Agapanthus lover or haver, please deadhead spent blooms before they have a chance to set seed and dispose of them in your green waste bin.