Aubrieta, Arabis and Aurinia trial 2024–2026

This trial features 72 distinct cultivar selections of Aubrieta, Arabis and Aurinia, all sourced, submitted, or donated by breeders and growers from across the UK.

The cultivars under evaluation display the following characteristics:

• Aubrieta – Renowned for forming vibrant carpets of colour in late spring and early summer. Most garden cultivars are believed to originate from Aubrieta deltoidea, a naturally variable species that includes both lilac and red-flowered forms
• Arabis – A versatile genus encompassing herbaceous, annual, and perennial plants. It produces long-lasting spring blooms in white, pink, or purple, and typically grows to around 15cm in height. Arabis is a popular choice for alpine and rockery gardens, as well as for container planting
• Aurinia – Formerly classified as Alyssum, this evergreen perennial reaches approximately 20cm tall. It forms a low mound of grey-green foliage, topped with abundant clusters of small, bright yellow flowers

Botanically, alpine plants originate from regions above the tree line – either on mountain ranges around the world or in the lowlands of Arctic and Antarctic zones. In horticultural use, however, the term ‘alpine’ refers more broadly to hardy plants suited to container cultivation, rock gardens, or cascading from wall crevices, where they can replicate their natural habitats on mountain slopes.

Throughout the trial, records will be kept of key growth stages, including the emergence of the first leaves and the onset of flowering. Each entry will be photographed to document overall habit and detailed floral characteristics. Group photographs will also be taken to assess uniformity within each cultivar.

The Aubrieta, Arabis, and Aurinia trial entries arrived at RHS Hyde Hall from a selection of suppliers and were planted out between March 2024 and April 2025, with the bulk of the entries set into the open ground of the Dry Garden trial bed in May 2024. The last date for planting replacements and new entries was April 2025.

Spring 2024 to spring 2025 was treated as an establishment year. This reflected both the short seasonal window available for sourcing these types of plants, and the added complication that many of the plants are misnamed in the trade, making the hunt for entries especially challenging.

Each cultivar was planted in groups of three, set out in a triangular arrangement with 50–60 cm spacing to promote healthy growth and adequate airflow. Following planting, the trial bed was carefully top-dressed with a fine layer of grit – enhancing drainage while lending the display a clean, refined appearance.

Throughout the initial establishment period, the plants were regularly watered until their roots were well anchored. Inevitably, a small number of entries and individual plants failed during this phase and were replaced to maintain trial integrity. No additional entries or plantings have been introduced since April 2025.

Before the trial began, a soil analysis confirmed that the allocated trial bed was in ideal condition and well-suited to support plant growth. To further enhance the planting environment, a fine layer of grit was applied around each trial entry, shielding the crowns, encouraging robust health, and helping to deter slug activity over the course of the trial.

Potential challenges

Three key alpine and rockery species are being observed during this trial, each with specific challenges that will be closely monitored:

• Aubrieta: May be affected by aphids and flea beetles and is susceptible to white blister
• Arabis: Vulnerable to Arabis midge and flea beetles. May be impacted by downy mildew, white blister, and virus infections
• Aurinia: May attract aphids, however is generally considered disease-free

All plants will be observed regularly for signs of stress or infestation, with any issues addressed promptly to ensure the integrity and success of the trial.