Phlox ‘Queen Paola’, Pycnanthemum flexuosum ‘Carte Blanche’ and Perovskia atriplifolia ‘Prime Time’ reign supreme at ISU Summer Days in Angers

Phlox ‘Koningin Paola’.

The Trial Commission of the International Hardy Plant Union (ISU) has announced the winners of this year’s ISU Awards, recognising excellence in plant performance, growth habits, colours, bee friendliness, and overall aesthetic beauty.

A panel of expert judges convened at the recently held ISU Summer Days in Angers and presented the coveted ISU awards to Phlox ‘Queen Paola’ and Pycnanthemum flexuosum ‘Carte Blanche’ (JS CARTE BLANCHE) – both submitted by Jan Spruyt-Van der Jeugd – and Perovskia atriplifolia ‘Prime Time’ submitted by Planttipp BV. The latter also submitted Euphorbia ‘KMMM024’ (MINERS MERLOT), which scooped up the ISU People’s Choice Award.

A total of 29 perennial novelties battled it out for the highest honour.

Jonas Bengtsson, president of the ISU Trial Commission, explained that all varieties had been extensively trialled for 18 months in the gardens of the Institut Agro Rennes Angers.

Bernd Hertle, Weihenstephan-Triesdorf University of Applied Sciences and chairman of the Perennial Plant Sighting Working Group of the Association of German Perennial Gardeners (BdS), shared the results of the jury.

ISU trialing is an European affair with a wide range of perennial plants being tested across 18 locations in Germany, Austria, Switzerland and the Czech Republic. These European trials give valuable insights into how plants perform under different climatic conditions.

Jo Bogaerts from Belgium said he would be happy if the trials could also be run in  Belgium. Ronald Houtman announced the future opening of a 4 ha trial garden in Boskoop, where green professionals can see, for example, side by side comparison of different Baptisia varieties.

The garden will be funded by membership fees and the city of Alphen aan den Rijn, among other sources. Paul Goderham updated the ISU Summer Days attendees about the trials in England, which are organised by the Royal Horticultural Society (RHS).

Winners of the ISU Awards 2024

Phlox `Koningin Paola´ submitted by Jan Spruyt-Van der Jeugd

Phlox ‘Koningin Paola’.

Phlox `Koningin Paola´ changes colour throughout the season, starting in pale pink and turning into dark purple. The variety stands 60cm tall with sturdy stems above which rise firm and compact flowers. Its flowering time is between June and August. This Phlox thrives in normal, not-too-dry soil and in a sunny spot.

Perovskia atriplifolia `Prime Time´ submitted by Plantipp BV

Perovskia atriplicifolia Prime Time.

This is an early-season blooming Russian sage featuring large, dense, lavender-purple coloured flowers that nicely contrast with grey-green aromatic foliage. Flowers retain their colour through October.  The plant’s dense, upright growth habit, sturdy 90cm stems, and free flowering character make it unique. Ideally, ‘Prime Time’ thrives in full sun, when placed in semi shade the soil must be well drained.

Euphorbia `KMMM024´ (MINERS MERLOT) submitted by Plantipp BV

Euphorbia Miner’s Merlot, Miners Merlot.

This vigorously growing Euphorbia has strong upright stems, dark green foliage, and early shoots and stems in burgundy red. The colour is even more intense in colder climates. In early spring, bright lime-yellow flowers rise above the dark foliage.

Winner of the ISU People’Choice Award 2024

Pycnanthemum flexuosum `Carte Blanche´(JS CARTE BLANCHE) – submitted by Jan Spruyt-Van der Jeugd

Pycnanthemum flexuosum `Carte Blanche´.

Pycnanthemum flexuosum, a perennial reminiscent of Monarda and Mentha and originating from the USA, is not a mainstream perennial but is becoming increasingly popular with gardeners and landscapers. The plant is also known as mountain mint and has a compact 40cm tall growth habit. It produces masses of white flowers between July and September. The plant thrives in full sun and not too humid soil.