RHS Plant Trials and Awards

Each year, RHS Plant Trials are undertaken with different plant groups to identify the best plants for your home and garden, with those performing exceptionally well receiving the RHS Award of Garden Merit (AGM)

What is an RHS Plant Trial?

View over the Trials Garden at RHS Garden Wisley

RHS Plant Trials allow for multiple selections of the same plant to be grown side by side for comparison. The best may receive a prestigious RHS Award of Garden Merit (AGM). The plants may be grown from seed or vegetative material, and are submitted by nurseries, individuals and breeders.

We trial a wide range of ornamental and edible garden plants and houseplants, including existing cultivars and species of plants, and brand-new introductions, to test their health, performance and weather resistance. This is to help home gardeners pick the best plants that have all-round value.

The trials are assessed by a judging panel made up of experts in that group of plants, who use the trial results to inform their decision to grant plants the RHS Award of Garden Merit (AGM) status. Each assessment is then ratified by the relevant RHS Plant Committee.

Visitors to RHS Wisley can view ongoing plant trials in the Trials Garden. Trials can also be seen in the dedicated beds at RHS Hyde Hall, RHS Rosemoor and in The Old Frameyard at RHS Bridgewater. Individual trials are regularly held at RHS Harlow Carr and sometimes take place at other gardens and nurseries across the UK.

The Forum judging the RHS Plant Trial of Origanum

“Each plant trial gives us the opportunity to shine a light on a plant group, showcase its diversity, and gather results to share with growers and gardeners.”

Rosalyn Marshall, Trials Project Manager

What is the RHS Award of Garden Merit?

The RHS Award of Garden Merit (AGM) is intended to help gardeners choose plants that are likely to perform, and is only awarded to plants that are:

  • Excellent for ordinary use in appropriate conditions
  • Available
  • Of good constitution
  • Essentially stable in form and colour
  • Reasonably resistant to pests and diseases

RHS awards can also be given by Roundtable assessment. An award is given when a forum of horticultural experts meets to debate the characteristics and performance of plants that the RHS is unable to trial in one of the RHS Gardens or another location.

To ensure consistent standards are maintained, the AGM is subject to regular review to make sure that every plant still merits its place on the list. Since 2013, reviews have been conducted by each RHS Plant Committee on a rolling basis.

Trials and planting ideas

Downloadable AGM lists

Using the AGM logo

The RHS Award of Garden Merit (AGM) logo is a registered trademark that is used throughout the horticultural trade, including nurseries, garden centres, online plant and seed suppliers, as well as publications. To use the logo for commercial use, please register your details with us and read the terms of use.

Find out more >
RHS Award of Garden Merit logo

Handy tools and information

Get in touch

For more information on our RHS Plant Trials or to access older trial reports, please get in touch with our team via email.

Get involved

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.