The Award of Garden Merit, or AGM, is an award made to garden plants by the British Royal Horticultural Society after a period of assessment by the appropriate committees of the Society. Awards are made annually after plant trials (which may last for one or more years, depending on the type of plant being trialled) at RHS Garden, Wisley and other RHS gardens, or after observation of plants in specialist collections, and are intended to judge the plants' performance for conditions in the UK. Trial reports are made available as booklets and on the RHS website. The awards are reviewed periodically in case plants have become unavailable or have been superseded by more recent, superior cultivars.
To qualify for an AGM, a plant
The AGM symbol represents a cup-shaped trophy with handles. It should be cited together with a hardiness rating as follows:
For plants requiring heated glass, further guidance is given as follows:
Minimum temperature
Since 1989, France has had similar awards called the Mérites de Courson, but these are drawn from a limited number of plants submitted by nurserymen to juries at the twice-yearly Journées des Plantes de Courson and the prizes are based solely on the opinions of the jury members as to the plants' likely performance in French gardens, not on extensive trials.