In 1759 botanists began rummaging around the world for specimens to plant in the 3-hectare Royal Botanic Gardens at Kew. They never stopped collecting, and the gardens, which have bloomed to 121 hectares, provide the most comprehensive botanical collection on earth (including the world's largest collection of orchids). A Unesco World Heritage Site, the gardens can easily devour a day's exploration; for those pressed for time, the Kew Explorer hop-on/hop-off road train takes in the main sights.
Don't worry if you don't know your golden slipper orchid from your fengoky or your quiver tree from your alang-alang; a visit to Kew is a journey of discovery for everyone. Highlights include the enormous early Victorian Palm House, a hothouse of metal and curved sheets of glass; the impressive Princess of Wales Conservatory; the red-brick, 1631 Kew Palace, formerly King George III's country retreat; the celebrated Chinese Pagoda designed by William Chambers in 1762; the Temperate House, the world's largest ornamental glasshouse; and the very enjoyable Rhizotron & Xstrata Treetop Walkway, where you can survey the tree canopy from 18m up in the air. A lattice fashioned from thousands of pieces of aluminium illuminated with hundreds of LED lights, the 17m-high Hive mimics activity within a real beehive. Opened in 2016, the 320m-long Great Broad Walk Borders is the longest double herbaceous border in the UK. The idyllic, thatched Queen Charlotte’s Cottage in the southwest of the gardens was popular with ‘mad’ George III and his wife; the beautiful carpets of bluebells around here are a draw in spring. Several long vistas (Cedar Vista, Syon Vista and Pagoda Vista) are channelled by trees from vantage points within Kew Gardens.
Check the website for a full list of activities at Kew, including free one-hour walking tours (daily), photography walks, theatre performances, outside cinema as well as a host of seasonal events and things to do.
Kew Gardens is easily reached by tube, but you might prefer to take a cruise on a riverboat from the Westminster Passenger Services Association, which runs several daily boats from April to October, departing from Westminster Pier.