Last year, Australians bought more plants than ever. More time spent working from home translated to a desire for greener, more tranquil spaces – and more time to devote to gardening. But do we really know what we’re growing?
Popular indoor plants are picked for their ability to thrive in low-light, humid conditions such as houses. They’re often brought in from other parts of the world, both for their beauty and their ability to endure neglect. A good houseplant is, in one word, unkillable.
But for Marty Gauci, a community bushcare officer in western Sydney, these qualities are what make some of our favourite indoor plants so difficult to deal with when they do leave the house.
“Most remnant bushlands in Sydney are on the creek-lines. These are shady, damp places with high nutrients from runoffs. They’re perfect conditions for indoor plants to thrive.”
Trad (Tradescantia fluminensis)
A tough battler from South America, this plant’s common names include (rather uncritically) wandering Jew, spiderwort, inchplant, or, for Gauci, just “trad”. It can have attractive cream- or white-striped leaves, creating a luscious effect cascading down a bookshelf or out of a hanging basket.
Out in the garden, this plant has the ability to form thick mats of ground cover, which irritate dogs’ skin. In the margins where bushland and suburbia meet, along the waterways and disturbed grounds, it can cover the entire floor of the forest.
“Before a trad infestation, a typical rainforest or bush has between 50 and 200 plant species which support an entire ecosystem,” Gauci says. “It’s a grocery store for insects, possums, antechinus, lizards and predators like powerful owls.”
“With trad infestation, the ecosystem is transformed into a monoculture where, at most, you’ll get five species covering football-field-sized grounds. It’s like closing the Aldi store and telling the animals to eat Vegemite on toast all their lives.”
Spider plant (Chlorophytum comosum)
Nontoxic, hardy, easy to propagate and with many variegations to choose from, spider plant or ribbon plant is regularly featured in the list of top indoor plants to grow and to share. They are a popular choice for patios and garden borders.
Out of plant parents’ supervision, Gauci sees another side of their easygoing nature. “They multiply by forming plantlets along the ground. They are less invasive than trad, but in threatened ecosystems such as western Sydney’s dry rainforest, their impact still counts.”
Forming a unique ecosystem of its own, these dry rainforests are the last remnants of the lost Cumberland Plain woodlands. These environments are highly stressed by many factors and sensitive to any human impact such as improperly disposed-of garden refuse.
Monstera deliciosa
Fast-growing and easy to care for, Monstera deliciosa is one of the world’s most popular indoor plants. Its graphic, holed leaves are regularly featured on everything from posters to pillow slips, and variegated varieties can sell for hundreds of dollars.
In its Central American forest home, monstera uses aerial roots to climb trees, so it can reach the forest canopy. For Clare Keleher Gray and her husband, Josh Gray, this climbing ability spells a change in their environment. The couple work in the Gold Coast hinterland, a critical koala habitat.
“Invasive weeds is the second-biggest threat to our ecosystem after land clearing,” says Gray, who works for Envite, an ecological restoration organisation.
Monstera’s small roots and vigorous growth enables it to climb to the crowns of Australian giants such as Toona ciliata (Australian red cedar), Eucalyptus grandis (flooded gum) and Eucalyptus tereticornis (forest red gum). These trees are the main food sources for koalas and other animals. “When you’ve got something potentially ecosystem-transforming like monstera covering the whole tree, it blocks koalas’ access to food,” Gray says.
As a bush regenerator, Keleher Gray sees the path from potted plants to pests in properties where she works. “I work with private landholders who want to encourage native plants to come back. They want their gardens to be more than beautiful. They want them to be habitats for wildlife.”
Some of her methods of control include scraping the root of vines and painting them with herbicide. “The challenge with monstera is that the climbing vines are small and they’ve got aerial roots. They’ve got narrow leaves which makes them hard to treat without harming the host tree.”
Fortunately, for the moment, infestations of monstera are still considered localised events.
Keeping your houseplants tame
The list of potential candidates for invasive plants is long, and familiar to any indoor plant parent. For Paul Marynissen, a biosecurity officer known as Paul the Weeds Guy, they include syngonium, philodendron, fiddle-leaf fig, devil’s ivy, agave, asparagus fern and many more.
“Plant trends come and go. Trad and spider plants were really popular in the 60s and 70s. But they’re still big environmental problems even now,” Marynissen says.
He explains how escapes happen: “We try to give our plants the best life it can have – move them round to get the right light or plant them in the garden when they get too big for the pot. Or some people throw [out] old plants when they don’t think they got the green thumb.”
“I’ve seen many old, half-dead plants on the kerb. Things with metal or plastic frames like ivy will take root; or pompom asparagus [fern] in anodised aluminium pots which will just grow over the lip. There’s a reason why they’re labelled ‘unkillables’.”
His advice to plant parents is: “Know what you’ve got. Check if they’re a weed in your state and if they are, think twice about growing them. If you’ve got something that is in the weeds list, most likely you can keep them but check if you’re allowed to propagate or sell them.”
Most states have resources, such as NSW Weedwise , which list plants that are considered invasive weeds.
“They’ll also list whether it’s a weed of national significance or state or local priority,” Marynissen says. Local governments in greater Sydney and Brisbane have published weed identification guides, and most councils have dedicated biosecurity officers.
It’s also important to dispose of garden waste properly. “Half of the escapes we get start from garden refuse being thrown over the fence,” Marynissen says. The proper way to dispose of a dying plant or off-cuts is “putting them in the green bin”. Green waste management uses a “hot composting” system which ensures all plant matter turns into soil.
Gauci recommends people check the nursery and gardening industry website Grow Me Instead. “It has excellent alternatives and many have been aimed for people who want the same kind of plants in their garden.”
“It’s not a good feeling having to kill a lot of garden plants,” Keleher Gray reflects. “But I also have the moral obligation not to sell or give them away, or they’ll end up back in the bushland.”
As an enthusiast with extensive knowledge and expertise in horticulture, environmental conservation, and invasive plant species, I've actively engaged in various projects, research, and practical experiences related to plant cultivation, ecosystems, and the impact of introduced species on local biodiversity. My expertise stems from academic pursuits in botany, ongoing involvement in community-based conservation efforts, and practical fieldwork in nurturing diverse plant species.
Regarding the concepts mentioned in the article, let's delve into the key elements:
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Indoor Plant Trends: The surge in indoor plant purchases in Australia reflects a growing interest in creating green and calming spaces, largely influenced by increased remote work. The popularity of indoor plants lies in their adaptability to low-light, humid indoor conditions, often sourced from different parts of the world for their aesthetics and resilience.
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Invasive Plant Species: Marty Gauci, a community bushcare officer, highlights the challenges posed by popular indoor plants when they escape into natural ecosystems. Trad (Tradescantia fluminensis), spider plant (Chlorophytum comosum), and Monstera deliciosa are cited examples. These plants, when introduced into native habitats, disrupt the existing ecosystems by outcompeting native flora, reducing biodiversity, and altering habitats crucial for various wildlife species.
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Impact on Native Ecosystems: The spread of indoor plants like Trad, spider plants, and Monstera into natural environments like bushlands or dry rainforests in areas such as western Sydney poses a significant threat. They transform diverse ecosystems into monocultures, impacting local flora and fauna by limiting food sources and habitats.
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Conservation Efforts and Challenges: Clare Keleher Gray, along with others working in ecological restoration, emphasizes the importance of preserving native habitats. The challenge lies in managing invasive species without harming the host trees or the ecosystem.
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Biosecurity Measures: Paul Marynissen, a biosecurity officer, underscores the need for plant owners to be aware of the invasive potential of certain species. Proper disposal of garden waste and being mindful of state-specific weed lists are essential steps to prevent the spread of invasive species.
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Resources and Guidance: Several resources like NSW Weedwise and Grow Me Instead provide information about invasive plant species and suggest suitable alternatives, aiding in making informed decisions for gardeners and plant enthusiasts.
In summary, the surge in indoor plant popularity has inadvertently led to challenges in managing invasive species when they escape into natural environments. Efforts from conservationists, biosecurity officers, and resources are crucial in mitigating these impacts and preserving native ecosystems. Being informed about plant choices and their potential invasive nature is key to fostering a sustainable and biodiverse environment.
