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 that are 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, Surrey

  • Narcissus (shorter types): 2022–2023
  • Helleborus: 2022–2024
  • Dahlia: 2023–2024
  • Oregano and marjoram: 2022–2023
  • Rosa (red-flowered): 2022–2024
  • Lathyrus (sweet peas): 2022–2023
  • Veronica (hebe): 2022–2024, RHS Garden Wisley, Surrey / RHS Garden Harlow Carr, North Yorkshire
  • Salvia (hardy): 2022–2024
  • Tulipa (early flowering): 2023
  • Fritillaria: 2023
  • Baptisia: 2023–2025
  • Delphinium (seed strains): 2023–2025
  • Aeonium 2023–2025, RHS Garden Wisley, Surrey / Minack Theatre, Cornwall

Trials at other RHS Gardens

  • Chilli: 2023, RHS Garden Rosemoor, Devon (behind the scenes at RHS Garden Bridgewater, Salford and RHS Garden Wisley, Surrey)
  • Primula: 2022–2023, RHS Garden Bridgewater, Salford
  • Helenium: 2023–2025, RHS Garden Bridgewater, Salford
  • Hydrangea paniculata: 2022–2024, RHS Garden Bridgewater, Salford
  • Gooseberries: 2023–2026, RHS Garden Bridgewater, Salford
  • Garlic: 2023, RHS Garden Bridgewater, Salford / RHS Garden Rosemoor, Devon
  • Climbing French beans: 2023, RHS Garden Bridgewater, Salford / RHS Garden Rosemoor, Devon
  • Spinach: 2023, RHS Garden Bridgewater, Salford / RHS Garden Rosemoor, Devon

Off-site trials

  • Chaenomeles: 2022–2025, Witch Hazel Nursery, Kent (open days only)
  • Hemerocallis: 2021–2023, Sissinghurst, Kent / Floors Castle, Kelso
  • Filipendula: 2023–2025, Royal Botanic Garden Edinburgh
  • Mahonia: 2023–2025, Sir Harold Hillier Gardens, Hampshire (behind the scenes)
  • Tillandsia: 2023–2025, Walton Hall and Gardens, Warrington

For more information on our trials please email [email protected].

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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.