Kew Unveils New Glasshouses

Two cutting-edge glasshouses, one permanent and one temporary, have been built as part of Kew’s ambitious project to renovate Kew’s iconic Palm House and Waterlily House.

While neither is open to visitors, the Propagation and Decant Glasshouses have been designed for the cultivation of tropical plants during the upcoming renovation of the Palm House and Waterlily House. Each uses advanced systems to control the temperature, humidity and light management in a more sustainable way. The Propagation Glasshouse is new a permanent structure, constructed behind the scenes close to Kew’s Tropical Nursery. The design is 5.50m in height to the eaves, enabling the safe movement of larger palms, cycads and other plants.

A temporary Decant Glasshouse has been built behind the Palm House using similar specifications but to a greater height. A temporary Decant Glasshouse has been built behind the Palm House using similar specifications but to a greater height to accommodate taller specimens. Together, these structures will house some of the world’s rarest and most threatened plants.

Cutting-edge technology and sustainable solutions

Advanced technology is at the heart of these new glasshouses, paving the way for the cutting-edge engineering that is fundamental to the Palm House renovation plans. The Propagation Glasshouse features the latest model of Elixa Heliospectra LED grow lights, which ensure optimal light levels year-round for tropical plants. In the UK, where tropical plants can suffer from either too much light during the summer or insufficient light during the winter months, these grow lights help maintain consistent ‘day-lengths’. This prevents plants from going into dormancy during the wrong season, promoting healthier growth and better resilience. The impact of this lighting system is already being seen in the Tropical Nursery, for example the rare Brighamia insignis (Hawaiian Palm, Alula), which is particularly sensitive to light levels, is thriving in response to these lights which replicate the natural light conditions it would experience in its native Hawaiian environment.

Alongside the new lighting system, the Propagation Glasshouse is also powered entirely by air source heat pumps. This is a more sustainable solution that reduces the carbon footprint of the glasshouse whilst regulating internal temperatures to 18°C–22°C. A glazed aluminium roof system featuring motorised ventilation and shade screening enables complete temperature control.

Sustainable water management

Water conservation is another major focus of the new glasshouses, as part of a wider sustainable irrigation strategy for Kew launched in spring 2024. The Propagation Glasshouse is connected to an existing rainwater harvesting tank, which is currently being renovated, so it can supply irrigation to the whole of Kew’s Tropical Nursery. The Decant Glasshouse features a 40,000-litre rainwater capture tank that will sit above the ground to store and filter water, using a coarse filter to sieve and remove debris and any coarse contaminants. These systems ensure that water used in the glasshouses is collected, filtered, and reused, reducing the reliance on potable water and lowering the environmental impact of the glasshouses.

Kew’s Palm House renovation project

The completion of the Propagation Glasshouse and Decant Glasshouse marks a significant milestone in Kew’s ongoing efforts to improve the sustainable management of energy-intensive buildings and builds upon Kew’s wider sustainability strategy with a target to become Climate Positive by 2030.

Richard Barley, Director of Gardens at RBG Kew, says: “We are proud and excited to announce the completion of these new facilities, which not only support the conservation of some of the world’s rarest and most endangered plants but also reinforce Kew’s legacy as a leader in horticultural innovation. These glasshouses mark the start of a project which builds upon Kew’s long history of pioneering horticultural excellence and will ensure Kew remains at the forefront of global plant conservation, while also setting a new standard for sustainability in botanical garden management.”

Preparations for the movement of plants from the Palm House have been in progress for some time, with pruning, cuttings, re-potting, and air-layering already taking place. Some smaller plants will be moved into the Decant House from autumn 2024, with a larger scale movement scheduled from spring 2025.