• AGM plants

    AGM plants have been through a rigorous trial and assessment programme. They are:

    • Excellent for ordinary use in appropriate conditions
    • Available to buy
    • Of good constitution
    • Essentially stable in form & colour
    • Reasonably resistant to pests & diseases
Zantedeschia 'Captain Lovely'

RHS Plant Trials provide the opportunity for multiple varieties of the same plant to be grown together, side-by-side, so they can be compared. They are assessed by an expert RHS forum panel who use the trial results to inform their decision to grant plants the RHS Award of Garden Merit (AGM) status. 

The plants are normally grown from seed and vegetative material submitted by nurseries, individuals and breeders. Visitors to RHS Garden Wisley are welcome to view them on the Trials Field. Off-site trials are also held at gardens and nurseries across the UK. Download the RHS Plant Trials programme for 2017-19, which includes many ornamental and edible crops.

Iris 'Lark Rise' AGMTrials results

You can download Plant Trials Reports and see details of current and past trials from the RHS Trials Database.

We also produce Grower guides which contain more information and interpretation to help gardeners make the most of the results of our trials.


Aeonium balsamiferumRHS Horticultural plant name database

Trials also provide an important spur for RHS research into cultivated plants and their names. Use this database to search a large index of garden plant names.

View the RHS Horticultural plant name database


RHS Herbarium

Trials are an important source of material for the RHS Herbarium located at Wisley, which comprises many separate collections. The primary focus of the collections is to maintain and to acquire reference material of plants in cultivation.

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