How to transform an urban garden: Chelsea Gold medallist uses lush, green plants and innovative materials to create a multi-storey idyllic retreat

How can you create gardens within the small outdoor pockets that are all you get in many modern blocks of flats? Designer Kate Gould took the RHS Greening Grey Britain campaign to heart, which encourages us to green up urban spaces.

Her multi-level solution at Chelsea Flower Show last week earned her a well-deserved Gold Medal. “With a bit of thought, you can make any tiny outdoor space outside your front door green and inviting, whether you’re in the basement, on the ground floor or at a higher level,” says Gould.

She recreated three levels of a blueprint apartment block, built off-site with a structure of steel beams, to put her point across.

The lush, green planting ranges from shade-tolerant tropical plants such as tree ferns, fatsia, philodendron and camassias in the basement, where light levels are lower, to more Mediterranean, drought-tolerant planting on the upper levels, including euphorbias, bush echium, lavender, polygala and an exotic lavender hibiscus.

There are two hawthorn trees on two of the small outside areas at the top, and a green wall of textural foliage on the outside, adding to opportunities for wildlife to feed and shelter — an important aspect of the RHS campaign.

But it is the innovative materials Gould used, with a predominant theme of grey and orange, including two giant Anglepoise outdoor lamps, that make these small-space gardens outstanding, and prompt us to think of new ways of landscaping our plots, whatever their size.

At the top level she chose plant-flattering Cor-ten steel for both a pergola, comprising a simple series of horizontal poles, and an interesting wall of linear abstract patterning that is repeated in a screen at basement level.

Raised beds and a banquette, fitted with a weatherproof bench cushion, are made of slatted powder-coated grey steel with a hammered finish that makes them, she points out, more durable.

“These kinds of materials — the Cor-ten steel wall, the planters — would be part of the infrastructure of the building. We took the pattern of the openwork screens and used it for the steel outside staircase as well,” says Gould.

Running between the Cor-ten screen and the banquette is a long, narrow planter holding strawberries and the exotic large leaves of glamorous vine Aristolochia, which trails right down the wall to the levels beneath.

Instead of solid safety walls, Gould used toughened glass to prevent the view being obscured.

The floor appears to be conventional decking in a rich nut brown, but is in fact thermo-treated bamboo fibre, sustainably sourced and increasingly popular with garden designers because of its stability as well as durability.

At the basement level, light is maximised with a white ceiling and walls of glazed white brick, in both flat and saw-cut finish, on one outside wall, where they create slight spray patterns in a fall of constantly trickling water.

The highlight — literally — of the space is the bespoke terrazzo inside stair wall down one side that, with the flick of a switch, emits thousands of twinkling, sparkling dots of light, creating a fairytale effect after dark.

For this, you can either pay about £80,000 for a slab of light-transmitting concrete, or roll up your sleeves like Gould did, enlisting help of her office team and friends.

“We cut up 3.8 miles of fibre optic cable into 75mm lengths, and stabbed all 80,000 into polystyrene bases within tile-shaped aluminium moulds, then carefully poured the terrazzo mix — clay with marble chippings — around the fibre optics to form the panels.”

Sometimes you have to go the extra mile to get the desired effect, as Gould knows.