Krater is a feral site reshaping Ljubljana’s ecological stewardship by embedding it in creative practices. It’s also changing the way international communities perceive invasive species.
Less than a 30 minute walk from the Old Town of Ljubljana, Slovenia, a team of creative young professionals have transformed a semi-abandoned patch of land into a site of experimentation, innovation, education, and advocacy. It is all centred around nature regeneration and stewardship, and includes prototyping forms of production using invasive plants – species usually seen as the scourge of healthy ecosystems. As a multidisciplinary collective breaking away from traditional industries, the team at Krater is informing new perspectives, better ecological stewardship, and community economies based on biomaterials.
Introducing Krater
According to its website, Krater is an 18,000m2 “overgrown construction pit”. That’s a nod to the succession of non-native plant species that are thriving on the remaining state-owned part of the site which. Until 1994, it housed a military barracks and was then used exclusively for gravel extraction before being earmarked for development by the Ministry of Justice. (After the war in Yugoslavia, the other three-quarters was replaced by a residential–business neighbourhood.) For now, it temporarily houses a “creative laboratory” that acts as a “terraforming agency,” run by a diverse group of young professionals, including lawyers, photographers, landscape architects, ecologists, and architects, who have gathered to question practices of repair and experiment within the site’s regeneration.
They first got to work here in 2020 with activities mainly focused on regenerative material cultures: experiments with wood, mushrooms, and paper made from biological material – or biomass – harvested from the invasive species thriving on the site, such as Japanese knotweed, Black Locust, and Canadian Goldenrod. These practices function as forms of ecological stewardship that challenge dominant eradication-based approaches.
It is a concept that’s likely to set conservationists’ blood pressure soaring. Left unmanaged, invasive flora and fauna are widely thought of as pests, and are known to be damaging to ecosystems, a threat to indigenous biodiversity, and even pose a danger to human health. But the world over, climate change is accelerating the rate at which plant species migrate; before we try to hold back the tide, Krater suggests that we see if this in fact provides opportunities to reinvent our relationship with urban nature – especially in the Anthropocene, when ecosystems are far from pristine.
Understanding Invasive Species
Not that the invasive plant species are here only because of climate change. Many of them were introduced to Slovenia as crops, garden flowers, or as unintended passengers of global economic flows, with seeds travelling along trade routes. But contemporary urban conditions – shaped by extractive economies, climate change, and biodiversity decline – result in a shifting ecological landscape and call for creative responses.
Instead of calling them “invasive species”, though, designer and Krater initiator Gaja Mežnarić Osole prefers to describe the non-native plants on the site as “feral” or “pioneering”. These terms better capture species that can take hold and regenerate degraded land where others struggle. Rather than being pests, they “produce soil, food, and habitat for more complex ecosystems to develop later,” she says. “We like to define the site as a ‘feral typology’,” adds Danica Sretenović, an architect and co-founder of the Krater collective. Today, Krater is home to more than 200 documented plant species, suggesting there is some truth to this perspective.
Invasive Species, Innovative Industries
It is unusual to hear about the potential benefits resulting from globalisation and climate change, but Krater does not take an ambivalent stance to conservation. The team says they approach it in an insurgent, experimental way. One such initiative is Notweed Paper, an innovative brand that produces industrially made paper from invasive plants.
The Krater collective’s motivation started very much as a response to the “crisis” young people graduate into, Gaja explains. She says that Ljubljana’s formal economy is steeped in the status quo, focused on maintaining existing structures and routines. “In other words, jobs and opportunities rarely allow for change, experimentation, or alternative ways of earning a living.”
That is not necessarily an issue in itself, except a new breed of professional is emerging that wants more from their career than a steady pay packet and to climb the corporate ladder.
Gaja’s studies in visual communications in the early 2000s were mostly “oriented towards supporting market economies”. They did not include the kind of positive socio-environmental impact she now seeks, which creative practices working in conjunction with nature allow the collective to explore.
I was always curious to orient my practice towards understanding in what way I can contribute to this world in a meaningful way. For me, working with natures has always been an essential part of this process.
Gaja Mežnarić Osole
It’s a story familiar to the disparate and disenfranchised individuals on the team and, seemingly, Ljubljana’s youth generally. “We put out the open call for internships and got 1,600 likes on Instagram and 1,000 new followers based on a non-sponsored post,” Gaja tells us. “It really shows that there are not enough spaces where eco-social designers or anyone from creative practice that is looking into more critical approaches can engage with after their studies.”
The Two Sides of Progress
Gaja further explains that Krater aims to plug what’s missing in the city by building on “the framework of diverse and community economies of [J.K.] Gibson-Graham”. The post-capitalist, feminist thinkers from Western Australia “who recognised a variety of non-monetary exchanges and community-making as vital to social resilience and collective wellbeing”.
The plurality of skillsets and influences that derive from Krater’s interdisciplinary collective have the potential to shape a commons-driven economic environment in the city, and one that transcends the opportunities offered by public funding and market economies. They’re also feeding into the much coveted Just Transition, which combines the creation of a greener economy with decent and inclusive work opportunities.
By advocating for feral typologies, Krater shows how alternative models for urban green space production and maintenance are made possible when there is a collaboration between cultural, creative, and environmental professionals. It opens up land for “other kinds of living and being in the space” than what most of us are used to, Danica says. However, this is not a utopia.
Why Some Green Space is Out of Bounds
Not everyone appreciates what Krater is doing for Ljubljana, or even knows about it.
There’s no open access for the public. As an official pending construction site, it does not appear as a green space on city maps, and the local community – although friendly and supportive when there are interactions – almost seems to have forgotten it was there. It is as if the fence that surrounds Krater “actually deletes the memory,” Danica observes. Admirably, the team accepts responsibility for this: “Community is something that you produce, it’s not something that is given.”
Krater’s core team of five, and the 15 or so others who come and go – and the volunteers who help out – meet this responsibility in many ways. Most notably through helping facilitate ties with the local community, through creative workshops for about 100 schoolchildren each year, site tours, and experimental biomaterial workshops, disseminating to the people of Ljubljana and beyond what this pioneering oasis does for the city.
An International Community
Gaja and Danica have also published a series of podcasts and videos under the name, “The School of Feral Grounds”, as part of their involvement with a cultural organisation that initiated Krater and formally supports several of its projects: Trajna Association.
These resources are an indication of Krater’s wider impact. Thanks to the digital age, the international stage of similar practices is listening and wanting to learn; the likes of the Floating University, Berlin; La Foresta Rovereto; Urbaniahoeve, Amsterdam; Tamale Ghana; Zakole Warshaw; Ministarstvo prostora, Belgrade; the Future DiverCities consortium; and the School of Architecture Sheffield Hallam University, UK, plus many others. “In that sense, the very physical existence of Krater contributes to practices and practitioners all over the world,” Danica says.
A Multifaceted Impact
But can a small collective of disparate, disillusioned young professionals and a feral site full of invasive plants really make that much of a difference? It certainly seems that way – and there have been some truly unpredictable outcomes.
They seem most proud of how the site has worked as a multiplier, inspiring “at least five-to-ten different masters or PhDs,” Danica tells us, again attracting people from diverse fields: geography, industrial design, textiles, and architecture. “From the educational point of view, this is the clearest impact.”
There aren’t many opportunities for kids to learn about caring for nature in Ljubljana, but Krater is one of them. Visiting students, during internships, learn how to be stewards of the natural world – including plants and, surprisingly, goldfish!
These non-native fish have started to populate Slovenia’s waterways, threatening to cause imbalance in the ecosystems. Rather than cull, a local veterinarian, Peter Maričić, tries to catch them, and Krater has set up an aquaponic fishpond so that they can continue living a happy life while serving a useful purpose: feeding on tiger mosquito larvae and helping make summers at the site more pleasant.
A Long-term Temporary Arrangement
Krater’s tenure is precarious.
Slovenia’s Ministry of Justice still has plans to develop the site into government buildings – shared with an officially recognised green space, at least.
The team has been signing year-long leases since 2021, as the Ministry’s plans get pushed back further and further. Like the invasive species they admire, the team is resilient in the face of uncertainty. Krater operates from temporary pavilions which can be easily removed and are low impact for the land.
Everything that we have put on the site was self-produced, self-organised, and intentionally mobile to comply with the conditions of the contract.
Gaja Mežnarić Osole
For now, they’re just grateful for having a suitable site.
Danica points out that “there is really no systematic support of this kind of collective work” and Krater’s relationship with the local administration has not always been easy – to the point where the authorities demanded to vet any articles in local newspapers before publication. Maybe the strong artistic, feral vibes of the risk-taking, experimental collective are seen as a threat.
The passion that makes it all possible, Gaja adds, is “not a given”. Without official support channels, much of what they’ve done has been for the love of it and sustained through mutual support: what they refer to as the “friendship economy”.
But finances matter. Rent needs to be paid, and everyone’s cost of living is creeping up. They earn a modest income through public funding and selling goods from what little the prototyping produces, but in the long-term, Krater needs to be integrated into the city’s socio-economic fabric to ensure its survival, Danica suggests.
“The question is, how to make a productive argument that this should be systematically funded by public funds, because our work is working for the public good.”
Recognition is Hard to Ignore
They are finally seeing a shift. Krater fits with the New European Bauhaus, an idea which brings together the green transition with an attractive built environment and practicality. Gaja says that this helps give them “visibility and recognition of the work that we do” on an international stage.
In 2023, Krater “won the highest national prize for architecture for public space,” Danica informs us. It was also the first Slovenian project to receive honourable mentions from an international “Landezine platform for landscape architecture” and they got a special mention at “the oldest graphic art biennial in the world, here in Ljubljana”.
International praise has put Krater firmly on the authorities’ radar and its role in the Just Transition and new city-based economies is finally being taken seriously, even making it eligible for public funding ringfenced for cultural and green initiatives.
Rising Community Demand
So the future is looking more secure, and just in time.
As urban spread causes Ljubljana’s community spaces to shrink, local people are also seeing the value in this space.
Danica says that they used their appearance at the biennial “to proclaim Krater as an art venue,” resulting in a “soft transformation” in public perception and gaining institutional recognition around the city for their work.
It seems like, at this moment, national politics in culture are recognising the work that we do.
Danica Sretenović
The site has since become an in-demand community resource for hosting events and activities for NGOs, theatre groups, dance troupes, students, even agroecologists and radio broadcasters.
“This is one of the last remaining spaces that allow them to organise something, and it’s for free,” which makes its preservation all the more important.
A Legacy of Socialist Commons
Krater shows that there can always be an exception to the rule – that other systems are possible.
Like probably every other modern city, Danica tells us that Ljubljana is a place of investor-urbanism, strict zoning plans, and examples of neo-liberalism which alienates citizens from urban land. But Krater perseveres because of a socialist legacy from Yugoslavia’s constitutional heritage.
All common infrastructure – such as cultural buildings, public spaces, and military sites – remains “publicly owned and commonly managed”, Danica explains. The site cannot be sold for development, and so will remain a green space until the Ministry of Justice decides to reclaim it.
This is not a contemporary Slovenia law, however, which is why Krater is advocating for updated ownership models, “such as planetary ownership, feral cartography, feral typology, and community of practice” which they hope will “surpass current hierarchical decision making on spatial governance”.
Gaja and Danica know that this cannot be taken for granted. They’re both mentors to a project called Future DiverCities, which imagines how degraded vacant sites in eight European cities can be transformed through a culture-led ecological regeneration. The toughest part of it, Gaja claims, was finding appropriate spaces “on which cultural organisations could plan their activities”. Krater is the pioneer other cities turn to for guidance.
From City to Global Economic Influencers
On the international stage, Krater is gaining attention for their situated eco-cultural production methods in places as far away as Ghana and Sweden, to the USA and the Netherlands. But Gaja stresses, they don’t just want to be showcased “as an example of what can be done” but rather for the impact that civic initiatives that co-produce cities can have, and the kinds of “governance structures that would enable more of these kinds of practices to happen”.
That includes ascertaining an understanding of how invasive species could be incorporated into city economies. And possibly even accepting that contemporary urban conditions – including climate change – offer some benefits.
Krater’s experiments with new ways of organising work, resources, and responsibilities aren’t fully defined or finished yet. Even so, Gaja sees “Krater as a signal, showing that cities require such spaces and new forms of governance and ownership models if they are to continue supporting cultural, social, and ecological practices that people care about.”
For more information about Krater, and to support their work, please visit the Krater website. Visitors to Urban Future in Ljubljana can also join a field trip to Krater on 27 March 2026 starting at 09:00.