9 January 2019

Secrets of the Palm House revealed

Palm House Supervisor, Will Spoelstra, reveals little-known secrets of Kew’s world-famous glasshouse, from nesting robins to our extraordinary tropical plants.

By Katie Avis-Riordan

View of the Palm House at sunset

Behind the glass

Built between 1844 and 1848, the breathtaking Palm House is still at the heart of Kew Gardens, offering a hot and humid environment for our tropical plants to thrive.

But what are the little-known facts about this magnificent Victorian glasshouse? The Palm House team of botanical horticulturists reveal all…

The Palm House secrets

1. Ever noticed that the Palm House looks like the upturned hull of a ship? That’s because the architects borrowed techniques from the ship building industry as no one had ever built a glasshouse of this size before.

2. The Palm House used to be completely green. The first curator of Kew, John Smith, thought green glass panels would provide extra shade for the plants. But this actually caused many problems for plant growth, especially with the industrial pollution from the 1890s, and was later recognised as a mistake.

Women gardeners at Kew Gardens, 1915

3. Originally constructed by engineer Richard Turner to Decimus Burton’s design, the Palm House has undergone two renovations in its time, one between 1955 and 1957 and the second between 1984 and 1988. The latter saw the Grade I listed building completely dismantled, restored and rebuilt.

4. We have robins and wrens nesting in our Palm House, enjoying the warmth of the tropical climate inside. Keep your eyes peeled for them on your next visit.

5. But birds aren’t the only surprising creatures found inside the glass and iron structure. A female Chinese water dragon called Techno lives near the papaya.

Techno the Chinese water dragon in Palm House
Techno the Chinese water dragon in Palm House

6. Our team is currently made up of two permanent members of staff with additional temporary students or apprentices. When the glasshouse first opened in 1848 there were six permanent staff members.

We are now also responsible for the Waterlily House and the surrounding beds, hedge and lawn outside the Palm House.

7. To cope with the heat and humidity inside this rainforest climate glasshouse, our team must stay well hydrated by drinking lots of water. The conditions are difficult at first, especially during the summer months, but we get used it. In the winter it is a pleasure to have such a warm glasshouse to work in.

8. One of the perks of the job is we get to eat the bananas and other tropical fruit produced in the house.

9. There are 16,000 panes of toughened glass, some of which are curved and very expensive. The panes are cleaned inside and out by professional glass cleaners every other year. We can clean the inside lower panes ourselves when required, which we do two to three times a year.

Exterior view of the Palm House in bright sunlight
Palm House, RBG Kew / Thom Hudson

10. The external ladders on the building are used for cleaning the glass, gutters and general maintenance by trained external contractors.

11. The floor is power-washed four times a year.

12. We have the oldest potted plant in the world here, the Encephalartos altensteinii, since 1775. We also have two very old Dioon spinulosum, one male and one female, and a Brownea X crawfordii, all since 1889.

13. Many rare and threatened species grow in the Palm House including several palms endemic to tropical islands, such as Ravenea moorei, from Comoros, of which there are very few left in their natural habitat. Another critically endangered, very beautiful palm here is the Pelagadoxa henryana.

14. Currently our tallest Palm House plant is the Cuban royal palm (Roystonea regia) but some of the giant bamboo shoots often grow taller than this before being cut back.

Interior of the Palm House
The Palm House ©RBG Kew

15. Recently we had to fell our oil palms which had reached the roof and broken through one of the glass panes.

16. Important scientific work takes place in the Palm House, including DNA research and finding new medicines. Recently, there has been a study of water retention in palms with relation to climate change. Our banana collections are key to the studies of wild crop related projects, including the hairy pink banana.

17. The Palm House is heated by a gas boiler situated in Kew's Shaft Yard, which circulates hot water through pipes around the house and underneath the paths. The temperature is maintained to a minimum of 18C. There is no maximum but we open the vents when it gets above 28C for the benefit of visitor and staff wellbeing.

18. We also have a misting unit designed to keep the relative humidity above 75%. Apart from the vents everything is controlled by our computer downstairs. On top of this we manually water every day.

Palm House trees

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