Happy 100th birthday to Chelsea! Show promises 'greatest ever' display for centenary celebration (and one family has been there since the beginning) Last-minute preparations are underway as the world's most famous flower show opens this week Among exhibitors is family firm Blackmore and Langdon, who have displayed every year since the show began A party of royal guests headed by the Queen will be given a sneak preview of the Chelsea Flower Show tomorrow Other royals attending include the Duke of Edinburgh, the Prince of Wales and the Duchess of Cornwall Prince Harry will show his grandmother around the B&Q Sentebale Forget-me-not garden created by his charity Come rain or shine, the green-fingered Langdon family have exhibited their prize-winning blooms every year since Chelsea Flower Show began a century ago. Now in their fourth generation, the family-run firm Blackmore and Langdon will join the many other exhibitors at the historic show, which opens its doors on Tuesday and this year celebrates one hundred years of glorious gardens. A party of royal guests headed by the Queen will be given a sneak preview of the Chelsea Flower Show tomorrow, ahead of its public opening. Celebrities are also invited to see the results of months of hard work from gardening experts, showcasing their designs in the week-long extravaganza, which organisers promise will be the 'greatest ever'. Green fingers: Charles Langdon (right, sitting), pictured in 1910 with his family, co-founded the prize-winning firm Blackmore and Langdon, which has displayed at every Chelsea Flower Show for the last 100 years Royal appointment: Charles Langdon (left) with Queen Mary in 1939 War effort: Workers at the firm help harvest tomatoes during the Second World War To mark the centenary, many gardens draw inspiration from shows of yesteryear - with others looking firmly to the future, including one that reacts to messages sent on Twitter. The Langdon family, who have faithfully made the journey every year from Bristol to London to exhibit their prize-winning blooms, will again display their first-class begonias and delphiniums, which have picked up a haul of 70 gold medals over the decades. With many years of experience behind them, Blackmore and Langdon were even at the Royal International Horticultural Exhibition in 1912, the forerunner to the RHS Chelsea Flower Show. And with just days to go until the 100th show, the Langdon family are among those putting the finishing touches to their display ahead of the opening to RHS members on Tuesday and Wednesday, and the general public from Thursday to Saturday. The landmark year has also led to a favourite of many a garden, the ornamental gnome, being given special dispensation - ordinarily, the Chelsea Flower Show has a strict ban on gnomes 'and other brightly-coloured mythical creatures'. Royals attending tomorrow will include the Duke of Edinburgh, the Prince of Wales, the Duchess of Cornwall, the Duke of York and Princess Beatrice. Prince Harry will also be there to show his grandmother, patron of show organisers the Royal Horticultural Society, around a garden very close to his own heart. The B&Q Sentebale Forget-me-not garden has been created by his charity, which is showing at Chelsea for the first time. Award-winning: Workers unwrap the begonias for the Chelsea Flower Show, 1950 Long-time winners: Staff stand in the begonia field in Bath, 1950 Bloomin' lovely: Stephen Langdon with pristine begonias, 1960 Fourth generation: Si, Steve & Nick Langdon are now at the helm of this long-running family firm The company first launched in 1901, when James Blackmore and Charles Langdon met at Bath flower show while exhibiting their prize-winning begonias. As friendship turned into business, the two decided to create a family-run company, selling small bunches of cut flowers from a tiny courtyard in Bath. A florist department was later added to the nursery, expanding the business that thrived on making wreaths and wedding bouquets. The family have now shared their fascinating story with ancestry website, Genes Reunited. Rosemary Langdon, third generation to the family business, said the secret to their success can be put down to hard work and dedication. She said: 'I think one of the really important things in keeping a business going for so long is keeping our values in the right perspective. We are very aware that nothing is achieved without hard work and dedication. We value our staff for all their hard work and we appreciate our customers for their loyalty. Look up: A gardener hangs azaleas in a floral display from the ceiling ahead of the Chelsea Flower Show, which opens on Tuesday Purple field: Lavender is one of the many colourful specimens on display Books in bloom: A gardener puts the finishing touches to the Birmingham Library garden Precision cutting: A worker ensures the Birmingham Library garden is plant perfect In preparation: A gardener carefully unwraps one of the plants on display at this year's Chelsea Flower Show Best in show: A gardener places a flower on his display ahead of the Chelsea Flower Show opening on Tuesday Head of Genes Reunited, Rhoda Breakell, said: 'Small companies such as Blackmore and Langdon are a truly inspirational example of years of hard work and dedication. Maintaining a successful family business for over a century is a fantastic achievement and they should be extremely proud to be exhibiting 100 years on from when it all began. Although John and Rosemary Langdon are now officially retired, their three sons, Simon, Stephen and Nicholas maintain the company's exemplary standards and continue to run the business. Yellow beauties: A display of daffodils at the Chelsea Flower Show, which celebrates its 100th birthday this year Spring in bloom: A gardener prepares these fine daffodils for the historic show Coming up roses: A worker puts together an intricate floral display ahead of the Chelsea Flower Show Red-y for the show: A Japanese Maple Bonzi tree dating back to 1955 is among the vibrant plants on display Blooming bouquet: A worker carries a handful of daffodils to a display Pruning and preening: A gardener prepares a Satsuki azalea Bonzi tree dating back to 1965 Pretty petals: A gardener prepares a Auricula Stella North flower