Diascia (twinspur), annual bedding trial results 2024
Objectives and purpose of the trial
View of Diascia plants growing in trial beds at RHS Wisley
Beautiful Diascia plants in the trial beds during summer 2024
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:
- Habit
- Flower power
- Vigour
- Pest and disease resistance
Diascia, annual bedding – RHS Recommended: AGM winners
Diascia Darla Light Pink
twinspur [Darla Light Pink]
- 0.1–0.5 metres
- 0.1–0.5 metres
Diascia 'Aurora Dark Pink' (Towers of Flowers Series)
twinspur 'Aurora Dark Pink'
- 0.1–0.5 metres
- 0.1–0.5 metres
Diascia 'Diamond Light Pink'
twinspur 'Diamond Light Pink'
- 0.1–0.5 metres
- 0.1–0.5 metres
Diascia Darla Light Pink
twinspur [Darla Light Pink]
- 0.1–0.5 metres
- 0.1–0.5 metres
Diascia 'Aurora Dark Pink' (Towers of Flowers Series)
twinspur 'Aurora Dark Pink'
- 0.1–0.5 metres
- 0.1–0.5 metres
Diascia 'Diamond Light Pink'
twinspur 'Diamond Light Pink'
- 0.1–0.5 metres
- 0.1–0.5 metres
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A cold and wet spring hampered this trial. Only the toughest plants were chosen so the new RHS Recommeded: AGMs really have the wow-factor.
Why the RHS Recommended: AGM was awarded
New award winners with forum comments
Voted AG (not quite meeting the full RHS Recommended: AGM criteria) with forum comments
Forum judging Diascia trial at RHS Wisley in July 2024
Judging of Diascia trial at RHS Wisley in September 2024
RHS Recommended: AGMs rescinded
Plants and location
What was planted?
Where was it planted?
Young plug plants and seed-sown entries were carefully planted out in two dedicated trial beds in the Trials Garden at RHS Wisley, Surrey. Here are some considerations for planting out Diascia annual bedding plants:
- Diascias perform best in well-drained soil
- Plants tend to be pest and disease free, but might be damaged by slugs and snails when young
- Check the predicted final size of the Diascia. Some grow taller while others have a more trailing habit
- You can buy diascias as plug plants or small plants. Keep plants bought in the spring protected from frosts before planting them out
- Diascias grow well in the ground and in containers, providing long-lasting flowering displays
Cultivation
Planting process
The trial was then planted out across two beds in the Trials Garden in May 2024. Eight plants of each entry were planted out in rows, with 40cm between plants in a row, and 40cm between each row. The beds were covered with strulch (a straw based mulch), to act as a weed suppressor.
The plants were fed once a week, initially with a water-soluble fertiliser and then with a balanced seaweed feed. No deadheading was carried out during the flowering season, to assess which entries continued to flower over the summer.
Heavy spells of rain caused flower drop across the trial in September 2024, but all entries reflowered. At the end of the flowering season, as each entry went over, the plants were cut back to a dome. The plants were left over winter to assess which entries survived through to early 2025.
How plant health was managed
Challenges
Flower bleaching was found to affect the flowering display, mostly in the red and orange flowered selections, causing white patches to form on the flowers. With the softer flower colours, bleaching was less noticeable and sometimes even added to the overall display.
Weather
Spring 2024 saw high rainfall and low sunshine hours. This contributed to a slow start to flowering across the trial.
Who was involved?
Judges of the trial
The Diascia annual bedding judges included: Paul Hansord (Chair, former Manging Director of Thompson and Morgan), David Creese (Westminster Parks, RHS Tender Ornamental Expert Group member), David Ford (Trials Coordinator for RHS Tender Ornamental Expert Group), Yvonne Walker (Plant Retail, former Manging Director of Hayloft Plants), Christopher Young (RHS Wisley Garden Manager, Formal and Decorative display, and RHS Tender Ornamental Expert Group member), Graham Rice (Garden Writer) and Duncan McLean (RHS Senior Plant Buyer).
Suppliers to the trial
List of plants in the trial
View all the Diascia annuals trialled at RHS Wisley
Handy tools and information
- Full article - Filter RHS Recommended: AGM plants by colour, height and season
Find a plant online
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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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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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