Hannah Gardner considers how using a biodiverse palette of plants presents designers with the means to create gardens and landscapes that are not only sustainable but are genuinely individual, varied, and original in content and appearance
What design opportunities are there for using especially unusual and biodiverse planting palettes? Several successful and very individual examples from recent public garden projects make good case studies.
Unsurprisingly, the huge botanical collection at the Royal Botanic Gardens, Kew offers great scope. ‘Some of the planting is experimental – we don’t know how well they will do, especially in the changing climate, but the diversity adds resilience,’ says Richard Wilford, referring to his informative designs at Kew, where he was Head of Garden Design for more than 11 years.
He cites two projects in particular where diversity was especially important. The 2019 Evolution Garden replaced the historic Order Beds, where plants were grouped according to their physical characteristics. The aim was to update classification groups and reflect how leaps in DNA analysis have clarified our understanding of plant evolution and also to demonstrate how plants have developed to attract pollinators. This is a fusion of science and horticulture, where science underpins the planting design process. Richard explains: ‘The garden is divided into eight “rooms”, representing major classification groups, and within each [of these], all the plants have evolved from one common ancestor, so are closely related.’
Given these parameters, he had the freedom to plant as he wished. Using reliable performers with a long flowering season, such as Salvias, Anemones, Rudbeckias and Echinaceas, he formed a colourful, resilient matrix and inserted more unusual plants amongst this to achieve diversity and include smaller plant families. He mixed the plants (instead of grouping them together) so he could experiment with dynamic plant associations, and they are ‘discovered’ as the public walk through the garden.
The second example is Richard’s final project at Kew, The Carbon Garden (opened in 2025), which offered him a unique opportunity to showcase the Botanic Gardens’ ongoing research. It combines scientific insight with thoughtful design and beautiful planting to highlight the role of carbon in our lives, how it moves through the environment, and how plants and fungi can help us tackle climate change. Themes such as the carbon cycle and the importance of photosynthesis, biodiversity loss, soil and fungi, and nature-based solutions are illustrated by different planting schemes within the garden.
The plants tell the story so, a dry garden in the climate-change zone features drought-tolerant plants such as Salvia yangii, Euphorbia rigida, Agave parryi, lavender, grasses (including Bothriochloa bladhii, Jarava ichu and Poa labillardierei), yuccas, and kniphofias. The climate-resilient trees include Ostrya carpinifolia, Cercis siliquastrum and Parrotia persica and they are underplanted with shade-loving perennials. There are also areas of unkempt grass, a wildflower meadow, and a woodland that includes decaying wood.
Interestingly, in the context of diversity and individualism, Plant Heritage is the Society of Garden + Landscape Designers’ (SGLD) new charity partner. The conservation organisation’s intention is to raise awareness of the amazing resources held by its National Plant Collection (NPC) holders and to encourage garden and landscape designers to use a wider range of plants, utilising the expertise of the collection holders.
‘What an opportunity,’ as horticulturist Jim Marshall VMH, a retired National Trust adviser of 25 years and double NPC holder, points out. He has been involved with Plant Heritage since it was set up in 1978 and believes it is the responsibility of NPC holders to make their plants available and to co-operate with suppliers because the National Plant Collections are ‘a living library and play a vital role in protecting plants for the future’.
This transition from specialist plant collection to commercially available designer/gardener favourite is illustrated by the expertise, vision and diligence of Sarah Cook VMH, who holds the National Plant Collection of Iris (Sir Cedric Morris Introductions).
Sarah grows 26 cultivars of these elegant and beguiling bearded iris in stock beds and mixed borders in her garden. An international quest to re-discover, assemble and then verify the provenance of the historic irises followed on from her departure in 2004 as Head Gardener of Sissinghurst Castle for 14 years and a return to Suffolk, her childhood home.
She is characteristically direct (and correct) in her assertion ‘to conserve a plant, give it away or better still, sell it’. For her part, having gradually built up her collection and to ensure the irises became widely available, Sarah initially passed some stock to David Howard, of Howard Nurseries in Norfolk, where the team there amassed enough plants to exhibit at the RHS Chelsea Flower Show in 2015 and win a Gold medal for the nursery’s display in the Great Pavilion.
The ‘Cedric Morris’ iris went on to become the centrepiece in 2023 of the enthralling, Gold-medal-winning RHS Chelsea show garden, The Nurture Landscapes Garden, designed by Sarah Price. The atmosphere and inspiration for that garden was drawn from the paintings of gardener Sir Cedric Morris (1889 to 1982) and showcased many of the plants he himself had collected and bred at his home, Benton End, in Hadleigh, Suffolk.
Behind the scenes, local connections had led to Sarah Cook and The Pinchbeck Charitable Trust (which had bought Benton End in 2018) working together, and the revival of the house and garden (to turn it into a place of art, horticulture and learning) was well underway.
Cook has since enjoyed further success at RHS Chelsea, exhibiting her iris cultivars alongside Iris Floreigium paintings and other National Plant Collections on the Plant Heritage stand at the Show in 2025, and her historic plants have caught the attention not only of growers and designers, but also of gardeners, professional and amateur alike. The bearded irises are part of the planting designed for the renewed Walled Garden, undertaken in collaboration with Sarah Price and which re-opened to visitors in the summer of 2026, and they also play a part in the ever-evolving tapestry of planting that Sarah Price created for the Exchange community gardens that surround an Edwardian Carnegie library in Erith, south-east London, which was converted into an arts centre in 2019.
This urban sanctuary garden was necessarily conceived by Sarah Price on a limited budget which, in itself, has encouraged a notable sense of individualism in the resulting garden. Many locally found materials have been re-purposed and excess plants from other projects re-homed among the fluid, atmospheric planting. This includes clumps of honey-hued Iris ‘Benton Susan’, which create a dramatic spring accent threaded, as they are, through Euphorbia seguieriana subsp. niciciana, Stipa tennuissima and Catananche caerulea in the narrow, free-draining Front Garden.
As designers and gardeners move forwards with raised awareness of the opportunities and benefits created by diversifying their planting palettes, they can also support climate resilience, demonstrate a commitment to improving and nurturing site ecology and support the specialist nursery industry.
In part two of this series (see December 2026 issue), we will consider the opportunities and freedoms for planting individualistic private gardens and consider how this works at scale in a modern residential development.
USEFUL ADDRESSES
Benton End, the Walled Garden will reopen to the public in 2027, gardenmuseum.org.uk/benton-end
Beth Chatto’s Plants & Gardens, propagates its Benton Irises from its own stock beds, bethchatto.co.uk
Claire Austin, offers a selection of Benton Irises, claireaustin-hardyplants.co.uk
Howard Nurseries, howardnurseries.co.uk
How Green Nursery SGLD ABP, offers some Benton Irises, howgreennursery.co.uk
Iris of Sissinghurst, offers a selection of Benton Irises, irisofsissinghurst.com
Plant Heritage, plantheritage.org.uk
Royal Botanic Gardens, Kew, kew.org
The Exchange, theexchangeerith.com
Photographs, (Carbon Garden/Mizzi Studio pavillion; Agius Evolution Garden) Alamy/Adrian Chinery
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