A garden built with “humble” terracotta made into 3D-printed bricks has won the first green medal at Chelsea flower show for being the most environmentally sustainable design. This year’s show, held in the Royal hospital gardens in south-west London, has a strong environmental theme. At the press day on Monday, Dame Judi Dench was presented with a seedling taken from the Sycamore Gap tree unlawfully felled in Northumberland. Dench, who has previously said she plants a tree every time one of her friends dies, said: “They let me name him and I named him Antoninus, after Hadrian’s adopted son.” The Roman emperor Hadrian built Hadrian’s Wall, where the Sycamore Gap tree stood. The environmental innovation award is the first of its sort at Chelsea, and goes along with the gold, silver gilt, silver and bronze medals awarded to the most attractive and interesting gardens, all of which will be announced on Tuesday. Giulio Giorgi, a first-time Chelsea designer, said he created the green medal-winning World Child Cancer Nurturing Garden with no concrete, and with completely sustainable materials. Most gardens contain concrete in some form or another and the materials they are built from often contain the highest carbon footprint. While the use of pollinator-friendly plants, wild areas and sensible use of water are well known, easy ways to make a garden more sustainable, Giorgi said it was important to focus on the building materials as their carbon footprint was often forgotten. It was also constructed by hand, with no power tools used, to reduce the carbon emissions of the process. Giorgi said: “Often we use a lot of metal, glues, cement, and then all the energy we have to put in to build the gardens. The material in our garden is low-temperature-fired terracotta, which we made into 3D-printed bricks, connecting ancient tradition with new practices. It’s fired at only 800C so it can be fired by electricity, without gas. So even if there is a little carbon in it, it’s the lowest possible, and terracotta stays porous, so it can take in water and release it when there is drought, which is very important. “And it also lets the air in and out which is very good for the root systems. So it’s a really good material for plants, but also for the planet because clay is a resource that can be found pretty much everywhere.” Malcolm Anderson, the Royal Horticultural Society’s head of sustainability, said: “The garden has been made using products made entirely from soil and timber and in its construction no power tools have been used, only hand tools, so it is a fine example of how we can design and build gardens more sustainably in the future.” Judges considered end-of-life plans for the gardens and whether materials could be reused. The 3D-printed nature of Giorgi’s garden and the way the parts tessellate together mean it can easily be dismantled and reassembled. As a result, when it is relocated to RHS Garden Wisley, in Surrey, where it will live on after the show as an educational facility, the carbon emissions will be low as no materials will be wasted and it can be transferred wholesale.