2020

Aralia 'Sun King'

2019

Stachys 'Hummelo'

2018                                       

Allium 'Millenium'

2017

Asclepias Tuberosa 'Butterfly Weed'

2016

Anemone x hybrida 'Honorine Jober'

2015

Geranium x cantabrigiense 'Biokovo'

2014

Panicum virgatum 'Northwind'

2013

Polygonatum odoratum 'Variegatum'

2012

Brunnera macrophylla 'Jack Frost'

2011

Amsonia hubrichtii

2010

Baptisia australis

2009

Hakonechloa macra 'Aureola'

2008

Geranium 'Rozanne'

2007

Nepeta 'Walker's Low'

2006

Dianthus gratianoplitanus 'Feuerhexe'

2005

Helleborus x hybridus

2004

Athyrium niponicum 'Pictum'

2003

Leucanthemum 'Becky'

2002

Phlox 'David'

2001

Calamagrostis x acutiflora 'Karl Foerster'

2000

Scabiosa columbaria 'Butterfly Blue'

1999

Rudbeckia fulgida var. sullivantii 'Goldsturm'

1998

Echinacea purpurea 'Magnus'

1997

Salvia 'May Night'

1996

Penstemon digitalis 'Husker Red'

1995

Perovskia atriplicifolia

1994

Astilbe 'Sprite'

1993

Veronica 'Sunny Border Blue'

1992

Coreopsis verticillata 'Moonbeam'

1991

Heuchera micrantha 'Palace Purple'

1990

Phlox stolonifera