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Who knew the Chelsea flu existed?
The RHS Chelsea Flower Show is the most prestigious gardening event in the world. As the highlight of the horticultural calendar, RHS Chelsea, held in London, is the place to see cutting-edge garden design, breathtaking floral displays, and innovative garden products, with some 168,000 visitors attending each year.
Garden designer and 'king of Chelsea' Mark Gregory likens Chelsea to 'haute couture'; RHS ambassador, garden designer and plantsman Jamie Butterworth describes it as 'the World Cup of gardening'; and the king of giant vegetables, Medwyn Williams MBE, calls Chelsea the 'horticultural Olympic Games'.
The RHS Chelsea Flower Show 2025, sponsored by the Newt in Somerset, returns from 20th – 24th May. Organised by the Royal Horticultural Society, RHS Chelsea has been held in the grounds of the Royal Hospital Chelsea in south-west London every year since 1913, apart from gaps during the two World Wars. But what else is there to know? Read on for some fascinating facts...
It was known as the RHS Great Spring Show in 1862 after launching in a large tent at the now-vanished RHS garden in Kensington. Between 1888 and 1911 it was held in the Temple Gardens on the banks of the Thames before moving to its current site at Royal Hospital Chelsea in 1913.
It may be the most prestigious but it is not Britain's largest flower show – that accolade actually goes to the RHS Hampton Court Palace Garden Festival, previously named the RHS Hampton Court Palace Flower Show.
A rock garden was the first type of Show Garden to appear at Chelsea in the 1920s. Between the two world wars, rock gardens were probably the most popular feature of the show, drawing large crowds. In 1980, there were only eight Show Gardens at Chelsea. This had more than doubled by 1985.
(Pictured: Rock garden at the RHS Chelsea Flower Show, 1938)
Show Gardens at Chelsea are built from scratch in 19 days and dismantled in five days, and over 2,000 tonnes of earth is moved in preparation for the show. Taking centre stage along Main Avenue, the inspirational Show Gardens are created by some of the world’s best-known designers and skillful landscapers.
In 1919, the government demanded that the RHS pay an Entertainment Tax – but with resources already strained, it threatened Chelsea. However, this was waived once the RHS convinced the government of its educational benefit.
In 1927 there was a campaign to get the RHS to ban foreign exhibits from Chelsea Flower Show to reduce competition with British firms. The RHS refused, saying 'horticulture knows nothing of nationality'.
In 1932 the rain was so severe that a summerhouse display fell to pieces. And one year when it was very wet, an exhibitor named it 'The Chelsea Shower Flow'.
Television presenter James May made a garden entirely from plasticine for RHS Chelsea in 2009, consisting of two and a half tonnes of plasticine, in 24 colours, moulded into an English cottage-style garden with a twist. It failed to win any awards, but protest was averted when James was presented with an ‘RHS Gold Medal’ made of plasticine.
(Pictured: James May's Paradise in Plasticine Garden)
Mark Gregory's breathtaking Welcome to Yorkshire Garden was one of the biggest highlights of the Chelsea Flower Show in 2018, so it was no surprise when it went on to win the People's Choice Garden of the Decade award in 2020.
The garden was a realistic representation of the Yorkshire Dales, celebrating Yorkshire's natural materials, traditional crafts and artisan food production. Monty Don said of the garden at the time: 'In all the years I've been coming to Chelsea, I've never known a garden that has had such an immediate reaction.'
READ MORE: Mark Gregory's Welcome To Yorkshire Garden wins People's Choice Garden of the Decade
In the midst of the coronavirus pandemic, Chelsea Flower Show was cancelled in 2020 for the first time since the Second World War. In its place, the RHS website became host to the Virtual Chelsea Flower Show, sharing free, inspiring content online from the gardening world.
The aim was to 'share the joy of gardening' with the nation through collaborations with growers, designers, landscapers and trade stands. With the pandemic ongoing, a second virtual show took place the following year in May 2021.
READ MORE: Chelsea Flower Show 2020 virtual show
Another knock-on effect as a result of the Covid-19 pandemic, for the first time in its 108-year history, in 2021 the Chelsea Flower Show was held in the autumn. The change in season was significant, as garden designers and exhibitors had to adapt and embrace the new September date with late-flowering plants, ornamental grasses and edibles taking centre stage.
During RHS Chelsea 2023, the RBC Brewin Dolphin Garden was left permanently damaged after orange powder paint was thrown across the plants and hard landscaping by Just Stop Oil protesters. Three women were arrested on suspicion of criminal damage.
Mark Gregory returned to Chelsea Flower Show in 2023 with The Savills Garden, which included RHS Chelsea's first-ever working kitchen. Chef Sam Buckley foraged and cooked daily from the ‘plot to plate’ garden and prepared a three-course meal for eight Chelsea pensioners.
READ MORE: Inside the Savills Garden
In another first for Chelsea, 2023 marked the first ever wedding to be hosted on the showground. Garden designer Manoj Malde married his partner Clive on the feature garden he designed: the RHS and Eastern Eye Garden of Unity.
Manoj said: 'How on earth is anyone going to accuse the RHS of being elitist when they are going to have the first RHS Chelsea wedding between a gay Indian man and a gay Irish man?'
Apparently, garden designers face getting the Chelsea flu every year. Garden designer Nina Baxter once told The Guardian: 'It is difficult to concentrate with lorries continually going past, and when people are stone-cutting, you get covered in dust. But the worst thing is when the plane trees on Main Avenue dump their pollen. It's horrible: you get it in the back of your throat and in your eyes – they call it Chelsea flu. Everyone hopes for a big strong wind overnight so it takes it off the trees all in one go.'
But there was a benefit to RHS Chelsea taking place in September back in 2o21. Monty Don said in Daily Mail’s Weekend magazine: 'Incidentally, one of the unexpected benefits of the show moving to September is that there will be an awful lot less sneezing. Many people react to the pollen from the London planes and find themselves sneezing, wheezing and coughing more than normal.’
In 2016, Juliet Sargeant became the first Black designer to create a garden at the Chelsea Flower Show. The Modern Slavery Garden was also Chelsea's first social campaign garden – it was awarded a Gold Medal and won the People’s Choice Award. Juliet returned to Chelsea in 2022 with the multi-layered New Blue Peter Garden, where she was awarded a Silver-Gilt.
READ MORE: Chelsea Flower Show designer Juliet Sargeant on why showmanship matters
Streptocarpus 'Harlequin Blue' (2010's Plant of the Year) was announced as Chelsea Flower Show's Plant of the Decade in 2020. It's the first separately bi-coloured Streptocarpus, with yellow on the outer petals, contrasting with the blue upper petals.
READ MORE: Chelsea Flower Show's Plant of the Decade winner revealed
The Chelsea Flower Show celebrated its 100th birthday in May 2013, and to mark the occasion, the Chelsea Plant of the Year became the Chelsea Plant of the Centenary – with Geranium 'Rozanne' (introduced by Blooms of Bressingham) winning the title.
The late Queen Elizabeth II had been the RHS' Royal Patron since 1952 and was a regular visitor to the Chelsea Flower Show with her parents as a child. But her first official visit as Queen was in 1955 – she attended RHS Chelsea more than 50 times during her 70-year reign. Her last appearance was at RHS Chelsea in 2022 where she was given a tour of the floral installations to mark her Platinum Jubilee.
READ MORE: King Charles III announced as new RHS patron ahead of Chelsea Flower Show
Every garden is judged by a panel of seven people. Not only is the judging process a lengthy one – up to 25 hours – but becoming a judge has also been described as a 'long, rigorous selection process, based on their level of experience and area of knowledge'.
READ MORE: How to win Gold at the Chelsea Flower Show: the judging process explained
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