Birmingham Botanical Gardens has re-entered one of horticulture’s more unusual international contests, pitting its giant Victoria waterlily against entries from botanical gardens, zoos, parks and museums worldwide in the fourth edition of Denver Botanic Gardens’ annual Waterlily Weigh-Off.
The competition, organised by the Denver Botanic Gardens in Colorado, challenges participants to discover how much weight a single waterlily leaf can support before it sinks. Last year’s edition drew more than 40 participants from nine countries, with Florida’s Bok Tower Gardens claiming the heavyweight title after its leaf bore an impressive 83kg. This year’s categories cover Lightweight and Heavyweight Waterlilies, with an additional Fan Favourite category decided by public vote.
Birmingham Botanical Gardens is returning to the competition with a Victoria ‘Longwood Hybrid’, a cultivar renowned for its exceptional size and strength. The entry marks a step up from the garden’s 2025 submission — a Victoria cruziana whose leaf measured 135cm in diameter and supported 34.2kg. The winning heavyweight entry is set to be announced on 26 August 2026.
A history stretching back 170 years
While the Weigh-Off is a modern fixture, Birmingham Botanical Gardens’ connection to giant waterlilies is deeply rooted in Victorian horticulture. The gardens’ Tropical House — originally known as the Lily House — was constructed in 1852, its centrepiece a circular pool measuring 24 feet in diameter. The impetus for the building came from a Victoria giant lily gifted by Joseph Paxton, the celebrated head gardener to the Duke of Devonshire at Chatsworth and later the designer of the Crystal Palace.
The structure was rebuilt in 1904 with an improved pool and heating system, then reconstructed again in 1977 to its original design, at which point it was renamed the Tropical House and stocked with economically significant plants from equatorial regions — among them bananas, sugar cane, cacao, yams and vanilla, many of which remain in the glasshouse today. Further renovation in the early 1990s, funded partly through community fundraising, saw a new double-glazed roof installed, ventilation improved and the pool fully reconstructed.
To optimise conditions for the giant lily pads, the pond’s water temperature has been raised to 25 degrees Celsius and the water dyed black to prevent algae from competing with the plants for light.
Part of a wider restoration project
The return to the Weigh-Off coincides with Birmingham Botanical Gardens’ ongoing multi-million pound Growing Our Green Heritage Project, a major restoration of the site’s historic glasshouses. As part of that programme, the Tropical House will be restored to its original name of the Lily House — a fitting tribute to the Victorian legacy that first brought giant waterlilies to Birmingham.
Alberto Trinco, Senior Glasshouse Horticulturist at Birmingham Botanical Gardens, said: “Giant waterlilies have fascinated visitors here for generations, dating all the way back to the 1850s, so we’re excited to be taking part in the competition once more. Last year’s 34.2kg waterlily was a fantastic achievement, but this year we’re hoping our Victoria ‘Longwood Hybrid’ can grow bigger and stronger. The competition is a wonderful opportunity to showcase just how remarkable these plants are and to share some of the horticulture skills that go into growing them.”
Members of the public can follow the competition’s progress on the dedicated Instagram account @WaterlilyWeighOff, and track Birmingham Botanical Gardens’ entry via @bhambotanicalgardens. Further information about the gardens is available at birminghambotanicalgardens.org.uk.
