The Award of Garden Merit, or AGM, is an award made to garden plants by the 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 The awards are reviewed periodically in case plants have become unavailable or have been superseded by more recent, superior cultivars. The Royal Horticultural Society was founded in 1804 as the London Horticultural Society, and gained its present name in a Royal Charter granted in 1861 by Prince Albert. ... Wisley, England is a small village in Surrey, between Cobham and Ripley. ... This Osteospermum Pink Whirls is a successful cultivar. ...

To qualify for an AGM, a plant

• must be available
• must be of outstanding excellence for garden decoration or use
• must be of good constitution
• must not require highly specialist growing conditions or care
• must not be particularly susceptible to any pest or disease
• must not be subject to an unreasonable degree of reversion.

The AGM symbol represents a cup-shaped trophy with handles. It should be cited together with a hardiness rating as follows: Some trophies seen in the London Irish clubhouse at Sunbury in 2002. ... Hardiness of plants is a term used to describe their ability to survive adverse growing conditions. ...

• H1 Requires heated glass
• H2 Requires unheated glass
• H3 Hardy outside in some regions or particular situations or which, while usually grown outside in summer, needs frost-free protection in winter (e.g. dahlias)
• H4 Hardy throughout the British Isles
• H1-2 Intermediate between H1 and H2
• H2-3 Intermediate between H2 and H3
• H3-4 Intermediate between H3 and H4
• H1+3 Requiring heated glass; may be grown outside in summer

For plants requiring heated glass, further guidance is given as follows:

Minimum temperature

• 15°C Hot glasshouse
• 10°C Warm glasshouse
• 2°C Cool glasshouse

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.

References

• RHS Plant Finder 2005-2006, Dorling Kindersley (2005) ISBN 1-405307366

External links

• The Royal Horticultural Society's website - Search facility for AGM plants
• RHS AGM Plant Awards
• RHS Plant Committees