Phalaenopsis (windowsill) trial 2024–2025

Objectives and purpose of the trial

This is a new trial format where volunteers are being asked to look after a Phalaenopsis (moth orchid) plant at home and send feedback that will help inform the RHS Orchid Committee on which plants are doing well. Those that perform best will be awarded the RHS Award of Garden Merit (AGM). 
Moth orchid plants create a colourful display on a windowsill
Moth orchid enjoying the windowsill light in a home setting

Plants and location

What was planted?

Twenty varieties of Phalaenopsis are being trialled with several plants of each variety. The orchid plants were given to 150 volunteers in April 2024 to look after at home, with each volunteer having one plant. When given out, the orchids were at a growth stage that is similar to those that could be bought in shops, with the flower spikes partly in bud and partly open.

Where is it planted?

Along with the home setting provided by volunteers, full sets of orchid plants are being trialled in The Orchid House and back office at RHS Wisley, Surrey and RHS Bridgewater, Greater Manchester, for data recording and comparison. Here are some considerations for growing moth orchids:

  • Moth orchids have been widely bred to produce many free-flowering and easy-to-grow hybrids
  • Grow in very loose, airy compost, mainly made of composted bark

  • Keeping the roots in good condition, not too wet or too dry, is the key to success with moth orchids

Phalaenopsis facts

These tropical orchids produce exotic displays of showy blooms that last for several months. The flowers come in a range of colours, most often white, pink or purple, but also shades of yellow, peach and burgundy. The petals may be veined, patterned or blotched with a combination of these colours. The tall, arching flower stems can be produced at any time of year and sprout from a clump of long, leathery, evergreen leaves.

Judges and criteria

Judges of the trial

This type of trial doesn’t have the usual judging panel assigned to it as the performance is based on information gathered from volunteers looking after the orchids for the RHS Orchid Expert Group to review. The information is being captured via short quarterly online surveys. Findings and expert tips are being shared with everyone by optional video calls, and the RHS Trials team hope to share the final results in early 2026.

Judging criteria

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

  • Healthy leaves
  • Strong and long-lasting flower spikes that branch evenly
  • Lots of flowers, evenly arranged  

  • Good size flowers with stable colour
  • Ease of re-flowering and quality of new flower spikes

Trial launch at the RHS Urban Show, Manchester
Display of the Phalaenopsis trial in The Orchid House at RHS Wisley

Cultivation

Planting process

The moth orchids were supplied by Double H Nurseries who grow the plants on over time, starting from smaller plug plants. When they were delivered to the RHS in April 2024, they were at a similar stage to shop bought plants with the larger plants in 12cm pots and the smaller ones in 9cm pots.   

Once the orchids were at a stage to begin the trial, an orchid was given to each volunteer to take home and care for. The RHS Trials team provided the volunteers with a grower’s guide to help look after the orchid with the following suggestions: 

  • Keep the orchid in the transparent plastic pot it arrived in. Phalaenopsis only need repotting every two years or so, to refresh the bark compost
  • Position the orchid in bright light. An east or west-facing windowsill is ideal. Keep it out of direct sun, as this can scorch the leaves
  • Moth orchids prefer consistently warm conditions all year round, 19–30°C during the day and 16–19°C at night
  • Water once weekly throughout the growing season
  • Feed lightly but regularly using a specific orchid fertiliser

How we’re managing plant health

Moth orchids are generally untroubled by pests and diseases and only occasionally attract mealybugs. The volunteers and RHS Trials team are checking plants regularly for white fluffy wax around the leaf bases and other hiding places, as the earlier it is spotted, the easier it will be to avoid them spreading. Picking off the bugs is the only way to control them.

It has been great to have so much interest in the trial so far and we are really keen to see the feedback information. Hopefully it is a way we could trial other houseplants in the future.

Rosalyn Marshall, Trials Project Manager
8 / 8
Display of orchids in The Orchid House at RHS Wisley
1 / 8
Young orchid plants at Double H Nurseries before delivery to RHS
2 / 8
Orchids monitored and stored in the Propagation facility
8 / 8
Display of orchids in The Orchid House at RHS Wisley
1 / 8
Young orchid plants at Double H Nurseries before delivery to RHS
2 / 8
Orchids monitored and stored in the Propagation facility
prev
next
How to grow moth orchids

Explore all the information you need to know to grow and care for moth orchids at home

How to grow moth orchids

Suppliers to the trial

List of plants in the trial

View all the moth orchids on trial at RHS Wisley, RHS Bridgewater and at home
  • Phalaenopsis ‘Birdie’
  • Phalaenopsis Anthura Denver (‘Phaldancip’)
  • Phalaenopsis Anthura Dover (‘Phalcomwel’)
  • Phalaenopsis ‘Electric Vibes’
  • Phalaenopsis Anthura Folkestone (‘Phalgondal’) 
  • Phalaenopsis ‘Honeybee’
  • Phalaenopsis Anthura La Paz (‘Phalgalyi’)
  • Phalaenopsis Anthura Linz (‘Phalfytyo’)
  • Phalaenopsis Anthura Milwaukee (‘Phalgaqxyk’)
  • Phalaenopsis Anthura Modena (‘Phalhoch’)
  • Phalaenopsis New Life (‘B9020’)
  • Phalaenopsis ‘Perceval’
  • Phalaenopsis Anthura Puebla (‘Phalfufly’)
  • Phalaenopsis Puppy (‘Mi00121’)
  • Phalaenopsis ‘Safe Haven’
  • Phalaenopsis Anthura Salta (‘Phalfauf’)
  • Phalaenopsis Anthura Santos (‘Phalcrazoh’)
  • Phalaenopsis ‘Sunny Shore’
  • Phalaenopsis ‘Violet Queen’
  • Phalaenopsis Anthura Zurich (‘Phalguoch’)
RHS Award of Garden Merit logo
Buy AGM plants at RHSplants.co.uk

Choose from hundreds of specially-selected plants, bulbs, seeds and gardening products in our online shop.

Shop now

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 at [email protected].

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.