“Anyone who thinks they’re too small to make a difference has never met the honey bee.” We’re buzzing to share that Sidara at 150 Holborn has joined the Camden BeeLine! 🐝

In association with London Clean Air, Think and Do Camden, and the London Borough of Camden, the Camden BeeLine is a community project increasing green space across Camden by creating a connected pollinator pathway of trees, plants, and rewilded space. With a particular focus on improving biodiversity, air quality, and wellbeing, this takes in schools and businesses growing on any space they can, from window sills to playing fields. And roof gardens. ✋

The Roof Garden at 150 Holborn

In July 2018, Sidara’s Landscape team was appointed to review the design of the 8th floor Roof Garden. This space has been transformed into an intensive green roof, primarily designed as an amenity space, accessible for recreational use by staff and visitors.

Benefits of Living Roofs:

Living roofs offer numerous advantages, including:

• • Enhancing biodiversity

• • Reducing the risk of flooding

• • Improving a building’s thermal performance

• • Lowering energy costs

• • Mitigating the urban heat island effect

• • Enhancing the city’s aesthetic appeal

Project Overview.:

Located in the London borough of Camden, the site was previously occupied by a nine-story mixed-use building at the junction of Holborn, Gray’s Inn Road, and Brooke Street. This building was demolished and replaced with a contemporary, sustainable mixed-use development in 2023. The plans for this site included upgrading the public realm, protecting the existing canopy trees, and supplementing the amenity space with an 8th-floor roof terrace and gardens. This elevated location offers commanding views of the city skyline.

Design Vision:

The vision for the roof terrace garden is to be an amenity space that provides a variety of functions. It offers intimate breakout spaces for informal staff meetings and presentations, creating an environment conducive to collaboration and communication. Additionally, it serves as a setting for fine dining and relaxation, allowing staff and visitors to enjoy meals and unwind in a pleasant atmosphere. The dynamic and inspiring environment is ideal for design workshops and staff events, fostering creativity and team building. Furthermore, the garden acts as a hub for outdoor presentations to existing and potential clients, showcasing the versatility and appeal of the space.

Sustainability Strategy:

The design implements a watering strategy that works in harmony with the rainwater catchment system and blue roof. To minimize irrigation requirements, a sustainable soft landscape palette using native and adaptive plants has been developed. Additionally, wind and drought-tolerant plants were selected, as no irrigation system was installed to meet LEED sustainability requirements

Peat-free compost:

In line with LEED sustainability goals, the compost selected for this project is peat-free. Peat is partially decayed organic matter that forms in waterlogged, anaerobic conditions. It is commonly found in wetlands such as bogs, from which it is extracted, causing the release of carbon dioxide (CO₂). Due to extensive peat extraction, these habitats are endangered in the UK.

Peat is a popular compost ingredient because of its excellent water retention, aeration, and drainage properties, as well as its acidity, which is valuable for cultivating ericaceous (acid-loving) plants. Sustainable alternatives include wood fiber, which has similar moisture retention properties, and composted bark, a byproduct of the timber industry which offers structure and aeration.

Blue roof and rainwater catchment:

A blue roof system is designed to manage rainwater by temporarily storing it on the rooftop, typically through various drainage layers and a waterproof membrane. This approach helps mitigate urban flooding by slowing down the rate at which rainwater is released into drainage systems, thereby reducing the burden on municipal infrastructure. The existing rooftop garden at 150 Holborn utilises a blue roof system alongside a rainwater catchment system. This setup collects rainwater and directs it into an attenuation tank. Recycled grey water is then used to flush toilets.

Plans for the future

Biodiverse and climate resilient planting:

The rooftop garden at 150 Holborn showcases a mix of native and adapted species to enhance biodiversity and attract wildlife. Prairie plants and Mediterranean species, both wind and drought-tolerant, could be added in the future with a view to adapting the scheme to a changing climate. Strategies to attract wildlife and create habitats for bees and birds, such as bug hotels and nest boxes, could also be implemented to improve biodiversity.

Engagement with the space:

The garden will establish affiliations with horticultural organisations and host workshops and events to actively engage users. Activities will include getting involved in planting and harvesting vegetables in a vegetable garden, creating bouquets and dried flowers from a cut flower garden, and improving the space’s inclusivity with additional seating areas. These enhancements will encourage communal dining and interaction, addressing staff observations that the current layout does not invite group gatherings.

Interactive information:

The garden will engage visitors and employees using interactive labels and interpretation panels. The labels will include QR codes linked to the RHS website for detailed information on key plants. These features will provide information about the plants and their ecological benefits, creating an educational and interactive experience. By fostering a deeper connection with the garden, these elements will enhance appreciation and understanding of the natural environment.

Existing plants:

Crataegus ‘Prunifolia Splendens’
Ornamental foliage that turns red in the autumn. Important food source for birds, which feed on the red winter berries. The flowers provide nectar for pollinators during the spring, making a valuable ecological addition to the garden.

Lavandula angustifolia
Mediterranean plant, drought-tolerant and highly scented. Key pollinator plant, particularly loved by bees. It is very versatile. It can be used to make perfumes and essential oils and has medicinal and therapeutical properties, for example to relieve anxiety. It has also cultural relevance, as the Romans used it for cooking, in their baths and to scent the air.

Verbscum ‘Gainsborough’
Mullein plants are architectural and add structure and height to herbaceous planting schemes. They attract wildlife and can withstand poor soil and dry conditions. They have been historically referred to as ‘torch plants’ because their dried stalks were dipped in fat or wax and used as torches.

Sesleria autumnalis
Attractive grass with vibrant bright-green foliage during the summer, turning golden yellow in the autumn. Low maintenance plant, drought and disease tolerant. Native to southern Europe, it typically grows in meadows.

Brachyglottis greyi
Well-adapted to dry climates, this plant has silvery foliage due to tiny hairs covering the leaf surface. These hairs help prevent excessive water loss through respiration, which occurs more rapidly in hot climates. As a coastal plant, it is also well-suited to withstand windy conditions. reducing the burden on municipal infrastructure. The existing rooftop garden at 150 Holborn utilises a blue roof system alongside a rainwater catchment system. This setup collects rainwater and directs it into an attenuation tank. Recycled grey water is then used to flush toilets.

Discover more, and how you too can get involved with the Camden BeeLine, here.