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24 Feb 2023

Over 100 participants from 16 nations on the 15th ISU Winterdays

Varied programme with top-class speakers


From 10 to 12 February 2023, more than 100 participants from 16 nations (Germany, the Netherlands, Belgium, Switzerland, Italy, Denmark, Sweden, Great Britain, Ireland, USA, Czech Republic, Hungary, Poland, Turkey, Lesotho and South Korea) met for the 15th Winterdays of the International Perennial Union (ISU) at the Bildungsstätte Gartenbau in Grünberg. Once again, Gerben Tjeerdsma from Sweden had organised a varied programme with top-class speakers.

The first speaker was Julia Cordsen from England, who reported on perennials in Kashmir, Buthan and Arunchal Pradesh, with fantastic pictures of Meconopsis in their natural habitats. Peter Korn from Sweden showed new projects and experiences with cultivation, culture and planting in sand and mineral substrates, which have great future potential in view of prolonged dry and hot periods or heavy rainfall events, not only in public and private green spaces, but also as roof and vertical greening. Afterwards, Yasemin Konuralp from Antalya in Turkey presented the impressive landscape of the Taurus Mountains and its rich geophyte flora.

The first lecture on the second day was eagerly awaited. Liesbeth Kap from the Ministry of Agriculture in The Hague, the Netherlands, presented the work and approach of the EU Commission in assessing and listing potentially invasive species. In view of the possible listing of Cortaderia selloana (pampas grass) and a resulting ban on trade, transport and distribution, the topic is highly topical. Pampas grass is one of the most important perennials in the garden and plant trade, with a trade volume of around 200 million euros per year (retail prices), as Aad Vollebregt, President of the ISU, explained. In the following discussion, which was unusually factual for the topic, alternatives for an EU-wide trade ban in the event of a listing were discussed, as the species has not yet shown any significant invasive potential - unlike Cortaderia jubata, which has already been listed since 2019. The necessity and possibilities of an early involvement of all stakeholders in the evaluation of the EU Commission were discussed, but also the personal responsibility of producers and nurseries to proactively and regularly inform themselves about the species under discussion in the Commission in order to be able to submit comments in time and to be able to weigh up economic risks. Another point of discussion was the different ways in which the regulation is implemented in the EU member states. While transitional periods of two years apply to farms in Italy and one year in the Netherlands to sell off existing stocks, in Germany plants and seeds must be destroyed or withdrawn from circulation immediately after coming into force. An unequal treatment, which Georg Uebelhart, Jelitto Staudensamen GmbH, rightly criticised. In the further discussion, fundamental aspects of neophytes and neozoa were also discussed, such as why species are listed EU-wide that only cause problems in narrowly defined microhabitats or on islands, to what extent one can still speak of "alien species" in a globalised world, or that, as Norbert Kühn from the Technical University of Berlin noted, in view of an impending loss of 40 to 60% of species in Europe due to climate change, we will be dependent on "exotic" species to preserve biodiversity. The participants agreed that, in view of higher temperatures and longer growing seasons, new species must be checked for potential invasive behaviour before they are introduced into the trade, and are aware of the personal responsibility of the industry, but also of private gardeners. Experience with some species that have been cultivated for years shows that their growth and spreading behaviour can change. The years of knowledge and experience of producers, growers, gardeners and users help in the assessments of the invasion potential and are indispensable for an objective evaluation.

After the excursion into politics, the tour continued to Lesotho. Bokang Ntloko, curator of the botanical garden in Maseru, presented the vegetation zones and the extremely rich flora of this country surrounded by South Africa. This was followed by a lecture by Ulf Nordfjell, landscape architect from Stockholm, Sweden, who presented various gardens and parks he has planned. An insight into the diversity of North American grasses and sedges was the subject of the presentation by Shannon Currey from Itzel Plants in the USA. Many North American species are also cultivated in Europe and have great potential as ground cover, lawn substitutes or for special applications such as slope greening or infiltration areas. Thomas Høvsgaard Vejs from SLA in Copenhagen presented forward-looking planning and greening projects for urban plant uses.

A tradition of the conference is the "Cuttings from your notebooks". On the second evening, participants had the opportunity to give short presentations about projects, special plants or interesting activities. Benedek Palotai, this year's recipient of the ISU Scholarship, kicked things off. Bettina Jaugstetter and Folko Kullmann presented the international symposium Dynamic Vision - Designing and Maintaining Naturalistic Plant Communities - which will be organised by the Gesellschaft der Staudenfreunde in cooperation with Bettina Jaugstetter and Anna Lena Hahn from 24 to 25 August 2023 in Mannheim. Linda Zimmermann, Michael Dreisvogt and Folko Kullmann, founding members of the sponsoring association Excellent Young Gardeners reported on the project to promote young gardeners, the current scholarship holders and alumni present introduced themselves. Thanks to the support of the Society for the Promotion of Garden Culture, this year's three Excellent Young Gardeners scholarship holders were able to attend the ISU conference. Annie Guilfoyle presented current Garden Masterclass projects and ISU President Aad Vollebregt this year's summer field trip to Romania. In October 2023, there will be a new format for exchange with the ISU Future Days in Prague, as ISU Vice President Tomasz Michalik and Committee member Jana Holzbecherova reported.

On Sunday, the two lectures by Norbert Kühn on the flora of the Appenines in Umbria and the plants of north-eastern Turkey and Anatolia by Yasemin Konuralp formed the conclusion of an all-round successful conference.

In 2008 Georg Uebelhart, Jelitto Staudensamen GmbH and member of the International Perennial Plant Union, initiated the first international meeting of perennial plant experts. Today, the ISU Winterdays are one of the most important networking events for producers, landscape architects and representatives of institutions who want to exchange information about perennials and other plants in landscape, nature and urban use.

The 16th International Perennial Plant Conference will take place in Grünberg from 16 to 18 February 2024.


The moderator of the ISU Winterdays and five of the international speakers.
The moderator and five of the international speakers: Peter Korn (Sweden); moderator Gerben Tjeerdsma (Sweden); Shannon Currey (USA); Julia Corden (Great Britain) , Bokang Ntloko (Lesotho) , Yasemin Konuralp (Turkey). (Foto: Folko Kullmann)
The more than 100 participants from 16 nations of the 15th ISU-Winderdays in Grünberg.
The more than 100 participants from 16 nations of the 15th ISU-Winderdays in Grünberg. (Foto: Matthias Hub)
After the break caused by Corona, the participants enjoyed being able to listen, learn and discuss again in the fully occupied lecture hall of the Bildungsstätte Gartenbau.
After the break caused by Corona, the participants enjoyed being able to listen, learn and discuss again in the fully occupied lecture hall of the Bildungsstätte Gartenbau. (Foto: Matthias Hub)

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