Current RHS Plant Trials

Every year, the RHS conducts trials to see which plants deserve the RHS Award of Garden Merit (AGM). Here are the trials taking place this year and beyond, on show to garden visitors

Aerial view of trials field at Wisley

Awards of Garden Merit (AGM)  are normally assigned after a physical assessment, judged by a panel of experts made up of specialist growers and renowned horticulturists. Slower-growing plants, such as some trees and shrubs, are judged by an expert panel via Roundtable discussion. Every year around 30 trials are held at venues throughout the UK, including at RHS Gardens.

Trials Garden, RHS Garden Wisley

  • Apiaceae family: 2021–23
  • Dahlia: 2021–23
  • Fritillaria imperialis (crown imperial): 2021–22
  • Helleborus: 2021–24
  • Hyacinthus orientalis (hyacinth): 2021–22
  • Lathyrus odoratus (sweet pea): 2021–23
  • Narcissus, shorter-flowering: 2021–23
  • Oregano and marjoram: 2022–23
  • Rosa, red-flowered: 2021–24
  • Salvia, hardy: 2022–24
  • Tomatoes: 2022
  • Tulipa, early flowering: 2021–22

Trials at other RHS Gardens

  • Celeriac: 2022, RHS Garden Bridgewater, Salford (and celery trial) RHS Garden Rosemoor, Devon
  • Cornus sanguinea and C. sibirica: 2021–23, RHS Garden Hyde Hall, Essex
  • Dianthus, border carnation: 2021–24, Bridgewater
  • Garlic: 2022, Rosemoor / Bridgewater
  • Geum: 2019–22, RHS Garden Harlow Carr, North Yorkshire
  • Helenium: 2022–25, Bridgewater
  • Hydrangea paniculata: 2021–24, Bridgewater
  • Melons: 2022, Rosemoor / Bridgewater
  • Primula: 2021–23, Bridgewater
  • Spring cabbage: 2021–22, Bridgewater / Rosemoor
  • Veronica (hebe): 2021–24, Harlow Carr / Wisley

Off-site trials

  • Aeonium: 2022–24, Minack Theatre, Cornwall (also Wisley)
  • Chaenomeles: 2021–24, Witch Hazel Nursery, Kent
  • Erica, winter-flowering: 2015–23, Threave Garden & Estate, Dumfries & Galloway
  • Hemerocallis: 2018–23, Sissinghurst, Kent and Floors Castle, Kelso
  • Mahonia: 2021–25, Sir Harold Hillier Gardens, Hampshire
  • Spiraea: 2019–23, East Ruston Old Vicarage Garden, Norfolk

For more information search our RHS Plant Trials database.

Return to RHS plant trials main page

Trials results for gardeners

See also

Gardening with the RHS

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The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.