The Teddington Gardener

Glasshouses at Kew

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Historical information

The Princess of Wales Conservatory was commissioned in 1982 to replace a group of 26 smaller buildings that were falling into disrepair. It was named after Princess Augusta, founder of Kew, and opened in 1987 by Diana, Princess of Wales. It is the most complex conservatory at Kew, containing ten computer-controlled climatic zones under one roof.

The two main climate zones are the ‘dry tropics’, representing the world’s warm, arid areas, and the ‘wet tropics’, housing moisture loving plants from ecosystems such as rainforests and mangrove swamps. The eight remaining microclimates include a seasonally dry zone containing desert and savanna plants, plus sections for carnivorous plants, ferns and orchids.

Whereas the Palm and Temperate Houses make grand statements with their designs, the low-lying, angular ‘glazed hill’ of the Princess of Wales house is less obtrusive. The conservatory was designed by architect Gordon Wilson to be energy-efficient and easy to maintain and was built partly underground.

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The southern end is heated more by the sun than the northern end, so this is where visitors find towering spikes of echiums and silver agaves from dry tropical regions such as the arid Canary Islands. The central area contains an elevated aquaria, complete with waterlily pond and the dangling roots of mangroves, plus displays of orchids and carnivorous plants. At the northern end are species from the moist tropics, including banana, pineapple, pepper and ginger.

Things to look out for

The pond within the aquaria section contains the Asian form of the giant waterlily Euryale ferox. This plant has huge leaves that can span two metres and are strong enough to take the weight of baby without sinking. On the lower level, there are viewing windows so visitors can see the pond from a fish’s eye view. Close by are separate tanks containing a rhombeus piranha, poison-dart tree frogs and baby water dragons. These displays demonstrate how plants and animals interact in their natural tropical rainforest habitats.

Towards the northern end of the glasshouse, are some familiar houseplants originating from the wet tropics. These include the African violet (Saintpaulia) and Swiss cheese plant (Monstera deliciosa). Once a year, the Princess of Wales glasshouse hosts a festival celebrating the beauty of tropical orchids. Kew’s orchid collection numbers some 1500 species, and staff working its micropropagation laboratory are becoming adept at bringing rare species back from the brink of extinction.

Behind the scenes

Keeping the Princess of Wales Conservatory’s plants in good shape requires much hard graft behind the scenes. The team clean out the pools in Spring, develop outdoor displays such as the Mediterranean Garden in Summer, top up the glasshouse’s soil and replant beds in Autumn, and prune plants throughout the winter.

The Davies Alpine House

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Historical information

There has been an Alpine House at Kew since 1887. The first house was built to a traditional design with brick foundations, wooden sides and a low-pitched glass roof. Potted plants stood on wooden platforms either side of a central path. This house was demolished and rebuilt to a longer wider design in 1939. A third Alpine House replaced it in 1981. With glass sides and roof, this was constructed using the state-of-the-art technology of the time. Its built-in systems were designed to control temperature, ventilation and moisture levels, while its pyramid shape reflected the mountain landscapes from which its inhabitants came.

Meeting the needs of alpine plants

In the wild, alpines spend the winter dormant. They remain dry and protected from extreme temperatures and the desiccating effect of cold winds by a blanket of snow. Spring arrives rapidly, with melting snow providing moisture for growth and exposing the plants to intense light. The short growing season means plants have to flower and set seed quickly. The Davies Alpine House was designed to create the cool, dry and windy conditions that alpine plants favour, without using energy-intensive air-conditioning and wind pumps. Its architects employed traditional practices and the latest technology to achieve this.

Although the glasshouse is only 16 metres (50 feet) long, its roof reaches ten metres (33 feet) high. This creates a stack effect that draws in cool air through permanent openings on either side and releases warm air through vents in the roof. Meanwhile, a fan blows air through a concrete labyrinth beneath the ground. The air cools on its convoluted journey and is released into the glasshouse through steel pipes. The panes of glass are 12mm thick and have a low iron content which allows over 90 per cent of light through. Meanwhile, fan-like shades on the east and west sides of the glasshouse protect plants from the most intense heat of the summer sun.

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Behind the scenes

Kew’s Alpine House team has built up a large collection of plants over time. Ranging from cushion plants from high-mountain environments to colourful bulbs from the Mediterranean, these are nurtured in the Alpine Nursery by four permanent staff and a trainee. Only when plants come into bloom and are looking their best do they go on display in the Alpine House. All the plants are grown in pots, enabling staff to provide the soil and watering regime that best suits each species.

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During hot summers in the old Alpine House the temperatures often exceeded 40°C. However, in the new glasshouse the temperatures generally remain below 32°C. According to Alpine House Keeper Richard Wilford, the plants used to look straggly from the reduced light after a two-week stint on display in the old Alpine House. Now, they thrive in the more favourable conditions and return to the Alpine Nursery looking as healthy as when they left.

Things to look out for

Throughout the year, the Davies Alpine House displays a wide range of campanulas, dianthus, small ferns, helichrysum, small lavenders, primulas, saxifrage, thymes, tulips and verbascums along with lesser-known species. One of the glasshouse’s rarest occupants is the Chilean Blue Crocus, Tecophilaea cyanocrocus. It has scented cobalt blue flowers with a white centre. Described in 1862, it was only known to grow in the range of hills surrounding Santiago, at about 3,000m. The plant was regarded as extinct in the wild from the 1950s onwards – due to unsustainable collecting by bulb dealers, overgrazing by cattle and localised habitat change – but was rediscovered in 2001 on private land south of Santiago.

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Text borrowed from the Kew website… my own pictures.

http://www.kew.org/visit-kew-gardens/index.htm

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