Hemerocallis trial results 2020–2023
Objectives and purpose of the trial
Hemerocallis trial in the Walled Garden at Floors Castle July 2021
Rows of colourful Hemerocallis at Floors Castle August 2023
What is an RHS Award of Garden Merit?
The RHS Award of Garden Merit (AGM) is intended to help gardeners choose plants that are likely to perform well, and is only awarded to plants that are:
- Excellent for ordinary use in appropriate conditions
- Available
- Good constitution
- Essentially stable in form and colour
- Reasonably resistant to pests and diseases
Judging criteria
The following factors were all taken into consideration as part of the judging of the trial:
- Complete plant: Garden value and beauty; vigour and good rate of growth, hardiness and resistance to pest and disease
- Foliage: Clean, healthy, appealing, in proportion to scapes and flowers
- Scape: Height and strength, in relation to flowers and foliage; branching and bud count
- Flower: Substance and weather resistance and colour(s) and pattern
- Distinctiveness: In flower, performance, season of bloom, scent, rebloom, unusual beauty, other special plant features
Hemerocallis AGM winners
Hemerocallis 'Dan Mahony'
daylily 'Dan Mahony'
- 0.5–1 metres
- 0.1–0.5 metres
Hemerocallis 'Marion Vaughn'
daylily 'Marion Vaughn'
- 0.5–1 metres
- 0.1–0.5 metres
Hemerocallis citrina
long yellow daylily
- 1–1.5 metres
- 0.5–1 metres
Hemerocallis 'Dan Mahony'
daylily 'Dan Mahony'
- 0.5–1 metres
- 0.1–0.5 metres
Hemerocallis 'Marion Vaughn'
daylily 'Marion Vaughn'
- 0.5–1 metres
- 0.1–0.5 metres
Hemerocallis citrina
long yellow daylily
- 1–1.5 metres
- 0.5–1 metres
Hemerocallis are tough and easy to grow. They will grow on most soils, are low maintenance, and don’t need staking. Who has time for staking these days?
Why the AGM was awarded
Early look at Hemerocallis trial in new trial area at Sissinghurst
Close up of Hemerocallis citrina on display as part of the trial
AGMs rescinded
Plants and location
What was planted?
Where it was planted?
This was a dual trial at two RHS Partner Garden sites – the Walled Garden at Floors Castle Walled Garden, Kelso, Scotland, with the kind permissions of the Duke and Duchess of Roxburghe and at the National Trust (NT) Sissinghurst Castle Garden, Kent. The trial was planted out in October 2018. Here are some considerations for planting out the Hemerocallis:
- Hemerocallis prefer well-drained, fertile soil but are adaptable and can tolerate poorer soils
- Plants prefer some moisture in spring and summer but dislike waterlogged soil
- Hemerocallis perform best in full sun but can also thrive in partial shade
- Richer-colored varieties may become bleached in scorching sun. Also avoid heavy shade as it leads to straggly growth and poor flowering
- Hemerocallis are fully hardy and do not require winter protection
- Most Hemerocallis are deciduous, losing their leaves in autumn, though some evergreen types retain their leaves year-round
Cultivation
Planting process
The Floors Castle Garden site used a bed prepared within the Walled garden, with each cultivar displayed using a triangle-grouping format along the west wall. Of the 52 entries displayed, five cultivars were only supplied and grown here.
Sissinghurst Castle Garden created a new enclosed trial area alongside their Vegetable garden where the same triangle grouping was used. Of the 69 entries displayed, only 13 cultivars were supplied and grown here.
How plant health was managed
Weather
During the Hemerocallis trial, plants looking to gain the RHS Award of Garden Merit (AGM) experienced extremes of weather in the flowering season including heatwave temperatures and torrential rain, and performed well without protection or special care in both Scotland and Sussex.
Challenges
To prevent the transfer of the Hemerocallis gall midge, which overwinters in the soil and can significantly reduce flowering displays, all plant entries were supplied with the soil completely removed. As an ongoing measure, the team looked out for key symptoms including distorted flowers and buds that failed to open.
How to grow Hemerocallis (daylilies)
Explore all the information you need to know to grow and care for Hemerocallis in your garden.
Who was involved?
Judges of the trial
The Hemerocallis judges included: Jim Marshall (Chair, Sissinghurst and RHS Herbaceous Expert Group member), Gavin McNaughton (Chair, Floors, Macplants Nursery and RHS Alpine and Rock Garden Expert Group member), Sarah Cook (RHS Herbaceous Expert Group member), Andrew Simmons (Retired Head Gardener of Floors Castle), Kirsty Wilson (Head of Gardens, Balmoral Castle), Dr Paula Dyason (Strictly Daylilies Nursery), David Moorsom (Specialist grower), Jim Gardiner (RHS Vice President), Paul Harris (Brookfield Plants), Lady Rosemary Fitzgerald (Beggars Roost Plants), Bob Brown (Cotswold Garden Flowers) and Andrew McSeveney (RHS Plant Trial Officer).
Suppliers to the trial
- A La Carte Daylilies
- Aulden Farm Garden
- Beggars Roost Plants
- Cotswold Garden Flowers
- Golden Acre Park – National Reference Collection, Leeds
- Howard Nurseries
- Macplants
- Strictly Daylilies
List of plants in the trial
Handy tools and information
- Full article - Filter for AGM plants and refine by colour, height and season of interest
Find an AGM plant online
Filter for AGM plants and refine by colour, height and season of interest - 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
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RHS Grow app
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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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