Ipheion (spring starflower) trial 2025–2026

Objectives and purpose of the trial

The purpose of this trial is to assess new and established Ipheion (spring starflower) varieties, focussing on Ipheion uniflorum selections. Ipheion is a spring-flowering bulb, with pastel-coloured, star-shaped flowers with strap-like green leaves appearing before the flowers, usually in winter. As Ipheion is less well known than other spring flowering bulbs, this is a great opportunity to showcase them at RHS Wisley, Surrey. As a relatively small trial, grown in containers, the RHS Trials team will have the opportunity to see the different varieties side-by-side, and those that perform best will be awarded the RHS Award of Garden Merit (AGM).
Ipheion plants in various stages of growth at RHS Wisley
Delicate purple Ipheion blooms emerging in early March 2025

Plants and location

What was planted?

The trial features 15 distinct Ipheion varieties, showcasing a broad representation of those currently on the market. These selections were thoughtfully sourced from breeders and growers across the UK and the Netherlands, chosen specifically for their potential in performance evaluation.

Photographs will be taken of each entry showing its habit and a close-up of the flower. The RHS Trials team will record when the first leaves emerge together with the flowering dates. The RHS Herbarium team may take a specimen from each entry to add to the collection.

Where was it planted?

This small trial features Ipheion bulbs grown in containers within the RHS Wisley Trials Garden, ready to deliver a vibrant burst of spring colour. Here are some considerations for planting out Ipheion:

  • Ipheion are hardy and can be planted in the ground, or containers, in a sunny, free-draining site which doesn’t dry out
  • They are perennials and will come back year after year
  • Ipheion have sweetly scented star-shaped flowers in late winter and spring with blue, white or pink flowers

  • Ipheion can be grown to add colour among dormant plants or around / under shrubs
  • Ipheion are early sources of pollen and nectar for pollinators

Ipheion facts

The narrow, strap-shaped leaves of Ipheion emerge before the flowers and, if bruised, smell of onion.

Judges and criteria

Judges of the trial

The trial assessment forum comprises 10 invited experts, with backgrounds in horticultural media, bulb breeding and supply, plant trials and garden management and design and members of the RHS Alpine and Rock Garden Expert Group. The trial forum will meet to assess the plants in April 2025, and after this initial assessment, the bulbs will need to establish for another year and be reviewed again spring in 2026.

The 2025–2026 Ipheion forum includes: John Amand (Chair, Director, Jacques Amand International and RHS Bulb Expert Group), Camilla Bassett-Smith (Television presenter, writer and RHS Bulb Expert Group), Ray Drew (Alpine Garden Society and RHS Alpine and Rock Garden Expert Group), Adele Dyer (Researcher at Which?, Which Trials), John Gibson (Bulb expert), Alex Hankey (Garden Manager, RHS Wisley), Jim McGregor (Alpine Garden Society and RHS Alpine and Rock Garden Expert Group), Kit Strange (Bulb specialist, RHS Alpine and Rock Garden Expert Group), Caroline Walter (Garden designer) and Richard Wilford (Royal Botanic Gardens, Kew and RHS Bulb Expert Group).

Judging criteria

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

  • Impact, balance of flower to foliage
  • Leaf quality

  • Flowering performance
  • Health and vigour

Ipheion trial plants brightening pots in early spring 2025 
Ipheion ‘Alberto Castillo’ with crisp white flowers in April 2025

Cultivation

Planting process

The Ipheion bulbs and young plants arrived at RHS Wisley in October 2024 and were planted out in mid-November 2024. The aim was to plant 100 bulbs per entry where possible, using terracotta containers (37 cm in diameter) filled with a mix of peat-free compost, loam, and grit. Each container was finished with a top dressing of grit.

Bulbs were spaced 2–5 cm apart and planted 5–10 cm deep, arranged in a spiral pattern from the centre outward. The number of bulbs planted for each trial entry was recorded. Due to limited availability, fewer bulbs were used for some entries, and in some cases, young plants were substituted. The pots were left outdoors over the winter of 2024 to ensure natural exposure to seasonal weather conditions.

How we’re managing plant health

Ipheion generally enjoy good resilience, with few issues related to disease. While they can occasionally attract slugs and snails, their overall health remains strong with minimal intervention.

Although Ipheion is not typically favoured by deer or rodents, some grazing was observed on a few leaves. To ensure continued protection and healthy growth, a fence was installed around the pots as a precaution.

It will be interesting to see how these delicate, pastel-coloured, star-shaped flowers perform and compare this spring.

Tricia Beer, Trials Project Leader
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Plant portrait of Ipheion uniflorum ‘Froyle Mill’
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Ipheion trial pots standing strong after a dose of winter in January 2025
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Fresh green foliage sprouts from trial pots, safely enclosed by fencing, at RHS Wisley in February 2025
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Plant portrait of Ipheion uniflorum ‘Froyle Mill’
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Ipheion trial pots standing strong after a dose of winter in January 2025
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Fresh green foliage sprouts from trial pots, safely enclosed by fencing, at RHS Wisley in February 2025
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Did you know?

To create a softer, more natural look, Ipheion can be planted beneath the dappled shade of a spreading tree.

Suppliers to the trial

List of plants in the trial

View all of the Ipheion on trial at RHS Wisley
  • Ipheion ‘Alberto Castillo’
  • Ipheion ‘Alice’
  • Ipheion ‘Dusky Pink’
  • Ipheion ‘Jessie’
  • Ipheion ‘Rolf Fiedler’
  • Ipheion ‘Tessa’
  • Ipheion uniflorum
  • Ipheion uniflorum f. album (syn. ‘White Star’)
  • Ipheion uniflorum ‘Charlotte Bishop’
  • Ipheion uniflorum ‘Froyle Mill’
  • Ipheion uniflorum ‘Hoo House’
  • Ipheion uniflorum ‘Miss Hannah’
  • Ipheion uniflorum ‘Rigel’
  • Ipheion uniflorum ‘Wisley Blue’
  • Ipheion uniflorum subsp. tandiliense
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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].

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