Hardy Plant Union discusses climate-resilient perennials at ISU Future Days in Prague

Perennial plant gardeners in Prague’s botanical garden: drought-tolerant plants are becoming increasingly important for urban greening across Europe. For years, the botanical garden in Prague has been testing appropriate assortments, which were visited during the excursion.

The International Hardy Plant Union (ISU) hosted its annual general meeting and conference in Prague between 12-13 October 2024.

ISU Future Days attracted 70 growers, landscape architects, and perennial plant aficionados from 14 European countries.

Day one focused on climate change and climate-resilient perennials.

Speakers and organisers of the ISU Future Days: back row, from left: Jakub Hamata, Theo Villier, Frans van Wanrooij, Stan Beekmanns, Sven Straeten, Herbert Vinken, Mirjam Vogt, John Little, František Hába. Front row from left: Aad Vollebregt, Tomasz Michalik, Jana Holzbecherová, Nico Rijnbeek. The speakers, James Hitchmough and Christoph Hokema are absent.

In his presentation, Petr Hanzelka from the Botanical Garden of Prague gave insight into plants that could better withstand an increasingly warmer European climate.

He discussed how he extensively trialled a range of Mediterranean and North American prairie plants in their natural habitat and Prague’s Troja botanical garden.

He believes the best drought-tolerant perennials are Aster sericeus, Muhlenbergia capillaris, Allium’ Millenium’, and, perhaps surprisingly, Heuchera pulchella, plants that attendees could spot during a tour through the botanical garden later that day.

James Hitchmough, a professor at the University of Sheffield in Britain, shocked the participants right at the start by saying, “We are all moving towards the equator…. In 2070, Budapest will be climatically on a par with southern Greece today.”

And what is the answer in the range of plants on offer? James and his PhD students compared the Howard Nurseries and Beth Chatto Nurseries catalogues by the water requirements of the taxa and found that in 30 years – there has been no change in the range. And that’s why he says: “Let the site drive the design. Don’t push the design onto the site.”

To preserve biodiversity, John Little from the United Kingdom suggested using entomologists to implement and design new habitats. He also questioned whether applying topsoil from another site to a planting area makes ecological sense. He prefers substrates, emphasising that a greater variance of materials – from crushed construction debris to sugar industry waste – will bring more habitat and extraordinary biodiversity.

Britain’s James Hitchmough made a strong plea for adapting ranges to the upcoming changes and using site conditions as a basis for plant planning.

Jakub Hamata from the Czech Republic discussed using computer waste heat to grow leafy vegetables.

František Hába from the flower farm Loukykvět explained how they have been organically gardening in Mšecke Žehrovice for six years and have succeeded in growing annuals and perennials for cutting.