Upon the release of a new book, we like to ask our authors to share their thoughts on the how and why of their work. In Wild Harmony - Urban Garden by Bart & Pieter garden designers Bart Haverkamp and Pieter Croes look back on the past 10 years of sustainable and intuitive work.
Hi Bart and Pieter, how did this book come about?
We felt it was the right time to pause and reflect on the gardens we’ve designed and built over the past few years. It's just nice to look back, but we also think it can be inspiring. Over the past ten years, we’ve really found our own voice. Apparently, our style has become recognisable. Some people call it rebellious — to us, it just feels natural. In every sense of the word.
We had lots of conversations and really took our time selecting the projects we wanted to include. The ones we chose are great examples of what a (city) garden or (roof) terrace can become. You don’t need a lot of effort, maintenance, or money to create something special. That’s a message we’re keen to share.
What characterises your designs?
Our gardens are plant-based — they start with the plants. We build them up like a painting, with layers, depth, and color. The plants tell the story. That way, the garden feels alive. Wild and untamed.
We hope our work helps people see green spaces differently. Nature doesn’t have to be tamed or controlled. If you give it room, it gives so much back: clean air, calm, inspiration — even a better chance of survival. That’s why it plays such a big part in the choices we make. For us, tackling the climate crisis is something we take seriously.
It’s also why we’ve moved away from lawns. They need a lot of water and aren’t very interesting for insects. We now prefer to create as much biodiversity as possible. For example, gravel may not seem eco-friendly, but many plants actually thrive in it.
Over the years, our designs have also become simpler. It might sound odd, but the more gardens we’ve seen and the more we’ve experienced, the stronger our craving for simplicity has become. Our designs are now even more plant-focused, with fewer constructions, and often using just one material. It creates calm, it's more sustainable, more practical, and often cheaper. The more techniques you use, the more people you need, which slows things down and raises costs. We’d rather invest in plants than in structures — better a hedge than a railing.
Why do you focus mainly on city and rooftop gardens?
Because even with just a few square metres of unpaved ground, you can create a garden that quickly becomes a fully functioning ecosystem — if you make the right choices. One well-chosen tree can offer shade, cooling, and a peaceful view for you and your neighbors. After years of hands-on experience, we’ve built up the knowledge to choose the right trees, plants, and soil for these kinds of spaces. That feels like a privilege — and one of the most rewarding parts of what we do.
City and rooftop gardens rarely offer perfect conditions but that’s exactly what makes them interesting. Limitations force you to get creative. On rooftops, for example, weight is a big issue. It can crush dreams — but also spark smart solutions. You start thinking about lighter soil mixtures, combining clay pellets, potting soil, or peat, and choosing plants and grasses with shallow roots.
What do you hope to achieve with this book?
With our work we want to show how much is possible when you let nature do its thing. Especially in cities, where every little patch of greenery is a small victory over all the concrete. We hope these projects will help people see urban green space differently, and that together we’ll start making more room for trees — so we can enjoy more shade, more cooling, and more diversity.
Check out the book
