RHS plant health principles

We have set six principles to guide plant health practice across the Society

There has been an increase in the rate at which harmful plant pests and diseases have become established in the UK. Diseases such as ash dieback and those caused by Phytophthora, and pests such as box tree moth and horse chestnut leaf miner are causing significant changes to our landscape and horticultural practices.

The risk of new plant pests and diseases being introduced is associated with the long-term trend of increasing volume and speed of movement of traded plants, and other material, imported from an expanding variety of sources. These risks were considered by the Government’s Tree Health and Plant Biosecurity Expert Taskforce which recommended actions to mitigate them and the Government’s approach to plant biosecurity is set out in Protecting Plant Health: A Plant Biosecurity Strategy for Great Britain

As a result of these increased plant health risks, we have revised our approach to plant health. We have written a statement and action points for industry and policymakers on biosecurity and Brexit and have implemented the following six principles which guide plant health practice across the Society. 

Our six principles

  1. Provide guidance on plant health issues to protect the sustainability of gardens and horticulture in the UK.
  2. Assess plant health risks prior to undertaking activities that are likely to have phytosanitary implications and identify what mitigations are required. 
  3. Adopt practices across RHS activities that minimise plant health risk, whilst balancing that risk with horticultural benefit.
  4. Prioritise and undertake research to generate the knowledge necessary to manage plant health risks to UK horticulture. 
  5. Communicate and exchange knowledge to enable informed decisions to be made to manage plant health risks to UK horticulture.
  6. Work collaboratively, internally through the RHS Plant Health Working Group and with external organisations to contribute to the management of plant health risks to the UK and to help develop the skills necessary to manage such risks.

To implement these principles we will make a number of changes to our horticultural, retail and shows activities.

The changes will be a process of continuous improvement with some practices already implemented, some being adopted within a matter of months (e.g. providing advice to non-members on exotic pests and diseases) and others being implemented over a longer period (e.g. holding imported trees in isolation prior to use in RHS Shows).

Changes we will make


  • Provide advice to the public (in addition to members) on how to report a new pest or disease affecting horticultural plants.


  • Wherever possible, continue to use UK-grown planting material.
  • Use least-risk plant material (e.g. certified seed) which is appropriate to the horticultural application.
  • Further develop plant reception capability in RHS Gardens to meet increased challenges.
  • Hold, in isolation, all imported semi-mature trees for at least 12 months prior to planting.
  • Develop a list of RHS-approved suppliers that meet specified plant health criteria.
  • Intensify surveillance for plant pests and diseases in RHS Gardens.


  • Ban plants that are particularly susceptible to diseases caused by the bacterium Xylella, from being exhibited at RHS Shows (unless UK sourced and grown).
  • Incorporate evaluation of plant health risk into judging criteria for gardens at RHS Shows; provide training for RHS judges and technical support during judging.
  • Request the Government's Animal and Plant Health Agency to inspect plants at principal RHS Shows.
  • Hold, in isolation, all imported semi-mature trees for at least 12 months prior to use in RHS Shows. 
  • Review and implement plant health policies for RHS Shows, including revision of plant health guidance, training exhibitors and staff, review of proposed planting lists, undertaking site inspections etc. 


  • Wherever possible, continue to use UK-grown planting material for RHS Retail.
  • Develop a list of RHS-approved suppliers that meet specified plant health criteria. 
  • Train staff in RHS Plant Centres in the detection of pests and diseases.
  • Intensify surveillance for pests and diseases in RHS Plant Centres.

Learn how to reduce plant health risks in your garden.

Pests and diseases

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.