Plot twists: Why experimentation belongs in every garden

Jacqui Hagen chatted to renowned plant practitioner Jac Semmler about the importance of trialling different species in the home garden, why context is key, and how we can do it all on a budget.

Heartland: Lessons from a living experiment

Tucked away in suburban Melbourne, Jac Semmler’s Heartland is a flourishing home garden and living laboratory, where constant experimentation and observation feed into her acclaimed plant practice, Super Bloom. Across the garden’s 400 square metres, Jac trials a diverse mix of native and non-native species, testing their adaptability to local conditions and their ability to coexist in ecologically sensitive ways.

The garden is in constant flux, shaped by seasons, microclimates, and Jac’s hands-on curiosity that treats success and failure as equal parts of the learning process. Through Heartland, Jac explores how resilient, place-responsive gardens can emerge from thoughtful trial and error, offering insights not just for her own space, but for gardeners everywhere. She shared some of these insights with us.

Start with your conditions, not your wishlist

No two gardens are the same; every site has its own microclimate, soil profile, and seasonal rhythm. By treating gardening as an ongoing process of experimentation and observation we not only create more resilient and responsive plantings, but also deepen our relationship with the unique qualities of our local surroundings.

Jac: “I promote a nuanced approach to planting, no matter where you are, which really considers the context and the purpose of that planting. And then, if appropriate, considering different combinations of plants as well.”

Take stock of what your garden offers naturally. Is your soil sandy or clay-based? Does it retain moisture or drain quickly? How much sun does each area receive across the seasons? What plants thrive in your neighbours’ gardens? Understanding your garden is the first step to choosing plants that will truly thrive, rather than just survive.

Jac: “What grows in a suburban garden will be completely different to what grows on a city rooftop, so it is really important to experiment with what will grow in the specific context of your own space, and understand its unique conditions.”

Trial, observe, refine

One of the practices that Jac values most is the ongoing testing of plant combinations: planting, monitoring, and adjusting over time. She was part of the team behind the Fed Square Test Garden that provides a window into Laak Boorndap, an urban garden project due to be completed in 2028 that will weave its way through Melbourne Arts Precinct (see below). In addition, over 1,000 plants are currently being tested on a rooftop at the University of Melbourne’s Burnley Campus in beds with shallow substrates and with minimal irrigation, to mimic the environment of the future garden before the full 18,000 square metres is planted. This same approach can be applied to the home garden; in Jac’s own garden hundreds of species have been trialled, with careful observation of how they cope with summer dry, sun, and different soil types.

Jac: “The whole concept of testing is such an important takeaway for home gardeners – you can just experiment at a small scale, figure out what works for your climate and your conditions, and then scale up from there.”

Mix natives and non-natives thoughtfully

Homes featured in Sanctuary are typically surrounded by gardens rich in native plants; maybe there are kangaroo grasses waving in the breeze, organically shaped pathways of crushed granite, and rockeries fringed by eucalypts and acacia. We’re huge fans of these kinds of gardens, as they provide habitat and food for local wildlife, and feature plants that are already suited to our often-harsh Australian conditions. And yet, many introduced plants have so much to offer as our climate shifts and our cities adapt.

Jac: “What I’m hoping to see is more of a nuanced approach to plants, no matter what their origin is. I would like to see plants not treated in such binary ways – that some are good and some are bad. Some introduced plants work so beautifully in our climate, and can provide great benefits; to give just one example, supporting invertebrates through the extension of flowering seasons.”

Jac has had great success with mixing in certain introduced species including succulents from Chile, wildflowers from California, and hardy perennials from the Mediterranean. Combining Australian natives with selected non-native species not only brings visual interest year-round, but creates a dynamic, multi-layered garden that offers food and habitat for wildlife while staying resilient and low-maintenance. This diversity doesn’t dilute ecological value, it strengthens it.

When adding non-natives, Jac reminds us to check what species are considered invasive in our local areas before planting.

Futureproof your garden

When the backyard at Heartland filled up, Jac got to work on the nature strip, experimenting with an approach she terms ‘dry dynamic planting’ – that is, plants that require no watering past establishment. In a city with unpredictable rainfall, she sees this as critically important.

Jac: “The approach of dry dynamic planting is about working with the climate, not against it. I choose plants that thrive in tough, low-water conditions, but still bring movement, texture, and seasonal change.”

In the context of Fed Square’s Test Garden, plants were selected not only for aesthetics but for their ability to endure extreme conditions, and to bounce back after tough periods. Some of the most successful combinations are those that can tolerate both flooding and summer dry, or that respond well to seasonal cutbacks and regrowth.

Jac: “I’m really interested in that beautiful resilience, where things can be really stunning and lovely and have all these seasonal fluxes but not require additional irrigation, especially in our dry area of the world.”

It’s wise to think long-term when planning your garden. Choose plants with proven tolerance to the extreme weather that can occur in your area, such as species with deep roots that stabilise soil and retain moisture in dry periods. Consider mixing perennials with annuals or bulbs that appear after rain. Create layered plantings that offer shade and reduce water loss from the soil below. These strategies will help your garden bounce back from periods of extreme weather with less intervention.

Learn by doing, not by spending

One might think that this experimental approach to gardening must come with a high price tag, but Jac assures us that this is not necessarily the case. Over 50 per cent of the plants in Heartland were propagated for free, and this process is a key part of the ongoing experiments on site.

Jac: “I love propagating. My first horticultural job involved propagating, and ever since I have been obsessed. It is fun and satisfying, and it’s free plants! You really can build a garden from cuttings, divisions, and seed saving.”

Jac recommends keeping an eye on what plants are thriving in your garden, and instead of taking just one or two cuttings, take fifty! These plants can form the backbone of your garden and will catch up to larger plants faster than you think. In general, she is a big fan of starting with small plants to keep costs low.

Jac: “I know that the horticultural industry encourages us to think that big is good: they want you to get a big pot and put in advanced plants for an instant garden. But what people don’t realise is that juvenile plants have so much vigour. So, the smaller the plant is when you put it in the soil, the sooner it will adapt to your circumstances and to your climate, and the faster it will grow in the end.”

Let your garden teach you

As our climate becomes more erratic, the lessons from gardens like Jac’s are increasingly relevant. Her practice offers a model that is a collaboration between plant, place, and gardener. Instead of sticking to a predictable suite of ‘safe’ species, Jac urges gardeners to trial broadly, and observe closely. Climate, soil health, water availability, and sun exposure all become active collaborators in the design process.

This mindset of curiosity and openness is something every gardener can adopt. Let your garden be a place of learning, and if something fails, embrace it as useful information to guide what comes next. If something thrives unexpectedly, explore why. Over time, your garden will become not just a landscape, but a conversation between you, the plants, and the place you share.

Further reading
thesuperbloom.com.au
artsprecinct.melbourne/laak-boorndap
fedsquare.com/events/test-garden