Phalaenopsis (moth orchid), windowsill trial results 2024–2025
Objectives and purpose of the trial
Moth orchid plants creating a colourful display on a windowsill
Moth orchid enjoying the windowsill light in a home setting
What is an RHS Recommended: Award of Garden Merit?
The RHS Recommended: Award of Garden Merit helps gardeners choose plants that are reliable and perform well in real gardens. Plants that receive the RHS Recommended: AGM have been thoroughly tested and shown to be:
- Easy to grow and reliable in normal garden conditions
- Readily available to buy in garden centres or online
- Healthy, robust plants with strong growth and appearance
- True to type, maintaining consistent shape, colour and form
- Reasonably resistant to common pests and diseases
Judging criteria
The following factors were 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
Moth orchids – RHS Recommended: AGM winners
Phalaenopsis New Life
moth orchid [Pisco]
- 0.5–1 metres
- 0.1–0.5 metres
Phalaenopsis Anthura Denver ('Phaldancip'PBR)
- 0.5–1 metres
- 0.1–0.5 metres
Phalaenopsis Anthura Puebla ('Phalfufly'PBR)
- 0.1–0.5 metres
- 0.1–0.5 metres
Phalaenopsis New Life
moth orchid [Pisco]
- 0.5–1 metres
- 0.1–0.5 metres
Phalaenopsis Anthura Denver ('Phaldancip'PBR)
- 0.5–1 metres
- 0.1–0.5 metres
Phalaenopsis Anthura Puebla ('Phalfufly'PBR)
- 0.1–0.5 metres
- 0.1–0.5 metres
I’ve had my Phalaenopsis for 21 years, so if you keep them happy, they can live a long life.
Why the RHS Recommended: AGM was awarded
The trial launched at the RHS Urban Show, Manchester
Display of the Phalaenopsis trial in The Orchid House at RHS Wisley
RHS Recommended: AGMs rescinded
Plants and location
What was planted?
Where was it planted?
As well as being grown in volunteers’ homes on windowsills in a range of rooms and aspects, sets of orchids were trialled at RHS Wisley, Surrey, and RHS Bridgewater, Greater Manchester. Plants were kept in The Orchid House and back offices to provide comparative data. 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
- Position your moth orchid in bright light. An east or west-facing windowsill is ideal. Keep your plant out of direct sun, as this can scorch the leaves
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 early 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 in mid-late April 2024 to take home and care for over a 13-month period. 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. Moth orchids 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. They do reasonably well in temperatures down to 10–12°C, but 15°C is better
- Water once weekly throughout the growing season
- Feed lightly but regularly using a specific orchid fertiliser
How plant health was managed
Challenges
Moth orchids are generally untroubled by pests and diseases and only occasionally attract mealybugs. The volunteers and RHS Trials team checked 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.
Location and heating
During the trial, moth orchids were kept on windowsills in a range of rooms and aspects. Although Phalaenopsis hybrids are generally tolerant plants, the trial highlighted conditions they do not cope with well. One participant, whose home was unheated, lost her plant. Moth orchids prefer warm, stable conditions and are sensitive to cold drafts, but they should also be protected from strong, direct sunshine on south-facing windowsills. Several participants noted that temperature fluctuations caused buds to drop. Once they’ve been watered, the roots turn green and healthy and then go silvery again when the plant needs water.
How to grow moth orchids
Explore all the information you need to know to grow and care for moth orchids at home
Discoveries
April 2025 | Unusual growths
Some of the volunteers noticed plantlets growing from nodes on the flowering stem of their orchids (known as keiki). These baby plants can simply be detached once they’ve grown several roots, then potted up in orchid compost to give you new plants for free. The RHS experts advised that keiki are sometimes produced when moth orchids have been stressed, so the volunteers who had noticed keiki were also able to check on the conditions their orchids were growing in.
December 2024 | Winter care
During the winter part of the trial, the volunteers fed back on how the temperatures in their homes were changing. The RHS experts advised not to leave orchids on the outside of curtains when closing them in the evening in the winter as they might get too cold. In winter, moth orchids do reasonably well in temperatures down to 10–12°C but 15°C is better.
Who Was Involved?
Judges of the trial
Suppliers to the trial
List of plants in the trial
Handy tools and information
- Full article - Filter RHS Recommended: AGM plants by colour, height and season
Find a plant online
Filter RHS Recommended: AGM plants by colour, height and season - Full article - Explore advice and helpful tips from our resident experts
Gardening advice
Explore advice and helpful tips from our resident experts - Full article - Check how hardy plants are using the RHS hardiness ratings system
Hardiness ratings
Check how hardy plants are using the RHS hardiness ratings system - Full article - A trusted gardening app packed with expert know‑how
RHS Grow app
A trusted gardening app packed with expert know‑how
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 RHS is the UK’s gardening charity, helping people and plants to grow - nurturing a healthier, happier world, one person and one plant at a time.