Philadelphus (mock orange) trial 2025–2030

Objectives and purpose of the trial

The purpose of this trial is to assess a range of Philadelphus (mock orange) species and cultivars readily available to gardeners. Concentrating on low and medium growing shrubs, the RHS Trials team at RHS Wisley, Surrey, will compare, record and display the merits of new additions against established cultivars, as well as identify the correct nomenclature (naming) for the species and cultivars in the trial. Those that perform best will be awarded the RHS Award of Garden Merit (AGM). This trial is also part of a Euro-trial, with the same trial also being run in eight other countries in Europe to see how the plants fare in different climates. The findings will be shared across the sites at the end of the trial.

Delicate blossoms of Philadelphus ‘Manteau d’Hermine’ in bloom

Elegant Philadelphus ‘Snowbelle’ showcasing lush white flowers

Judges and criteria

Judging criteria

The following factors are all taken into consideration as part of the judging of the trial:

• Overall impact and habit
• Floliage quality and colour
• Flower scent

• Foliage colour and quality
• Health and vigour
• Resistance to pest and disease

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 at trials@rhs.org.uk.