The show, now in its sixth year, celebrates these beautiful blooms within the elegant Chiswick House Conservatory, a 300ft glasshouse designed by Samuel Ware in 1813 for the 6th Duke of Devonshire.
The camellia collection at the west London estate is a national treasure and believed to be the oldest collection under glass in the Western world.
For the second year running the show remains free to the public. Chiswick House and Garden's Trust director, Clare O'Brien, said: "We made admission free to the show last year as we wanted as many people as possible to come and enjoy the unique collection of camellias and learn about their fascinating history.
"It was a resounding success with over 16,000 visitors – a record attendance, and over four times bigger than previous years. We were delighted that so many people recognised the importance of our work and gave a voluntary donation towards us keeping high standards of maintenance in the Grade I listed park. Chiswick House and Gardens are enjoyed by many thousands of people, not to mention their dogs, all year for free."
All Chiswick's plants are from the Camellia japonica species. The original collection was ordered by William Lindsay, the 6th Duke's Head Gardener, from Alfred Chandler's Vauxhall nursery. The number and name of all the varieties were not detailed but visitors' descriptions include references to varieties of C. japonica such as 'Alba Plena', 'Welbankiana', 'Lady Granton', 'Lady Hume's Blush', 'Woodsii', 'Beali' (now 'Beali Rosea'), 'Nobilissima', 'Imbricata', 'Chandleri' and 'Elegans'.
Today's conservatory collection of 33 different varieties includes many of the earliest varieties introduced to Britain. Using stem girth as an approximate guide it is probable that the Camellias identified as C. japonica 'Variegata', 'Imbricata', 'Chandleri', 'Alba Plena', 'Pompone', 'Aitonia', 'Corallina', 'Rubra Plena' and 'Rubra' are all from the original 1828 planting.
Also from the original group is the unique Middlemist's Red, brought to Britain from China in 1804 by Londoner John Middlemist, a nurseryman from Shepherds Bush. It is one of only two in the world known to exist – the other being on the other side of the globe in Waitangi in New Zealand.
The Chiswick House Camellia Collection had been in danger of being lost as the conservatory fell into ruin in the last years of the 20th century, but members of the International Camellia Society stepped in to tend them, ensuring their survival prior to the major restoration of Chiswick House Gardens, completed in June 2010.
Over the last eight years the trust has initiated a propagation programme to ensure the future of these rare specimens. Keen gardeners can buy heritage varieties from the original collection at a pop-up shop at the show.
Last year the shop sold 250 plants propagated from 16 heritage varieties in the rare Chiswick House Camellia collection to ensure the plants' future.
This year there will be another chance to buy Chiswick House's heritage varieties and some specially selected spring flowers. The pop up shop will also be selling Camellia cards and other Camellia inspired merchandise, and the cafe will be serving a seasonal menu.
The trust will also be organising schools workshops during the show, track the camellias' original journey from China.