The Queen and Duke of Edinburgh will be among the first people to get a glimpse of the exhibits at this year's Chelsea Flower Show when they tour the event in private.
The world's most famous flower show, which has been held in the grounds of the Royal Chelsea Hospital since 1913, will be open to the public from tomorrow but special guests including the royal couple will get a sneak peak later today.
Visitors are expected to flock in their thousands to see displays of plants, flowers and furniture for ideas on how to decorate their gardens.
Recent wet weather has failed to dampen the spirits of the hundreds of exhibitors who come back every year to showcase a mix of traditional, contemporary and sometimes wacky designs.
The entrance to the central London site is expected to be dominated by show regular Diarmuid Gavin's 24-metre tall pyramid-shaped design.
The Westland Magical Garden is made up of scaffolding constructed over eight levels, all covered in greenery but with different themes.
The award-winning designer said: "I am interested in structure, in planting and in how people use their gardens.
"I'm also concerned about the lack of space for people to garden or care for the environment at a time when there is pressure for more and more housing on our crowded island.
"So instead of having just one patch of garden, I thought why not have seven gardens one on top of each other."
Bellboys will take people up the levels in lifts, with the option of a stainless steel tube to slide back down.
Dublin-raised Gavin said the inspiration behind it was the Albert Bridge, which is close to the site.
Other eye-catching exhibits include an installation featuring dozens of green perspex rods to create a cage-like display with orchids, ferns and tulips growing inside.
Its designer, Tony Smith, said the structure, which is six metres long, three metres wide and two metres tall, was designed to represent two of the seven deadly sins.
Smith, based in Haywards Heath, West Sussex, said: "I was thinking of the phrase 'green with envy', and then thought about how people can get quite envious about other people's gardens, which leads to desire.
"Tulips, ferns and orchids are all plants which have been highly collectable at different times, so I've used white ones to show that it's no fault of their own, while the grass and lights inside are green and red, the colours of desire and envy."
He said the making of his elaborate creation had not been hampered by the rain, but more by the dusty conditions at the site, which led to some of the perspex being damaged.
London artist Tony Heywood said his own colourful creation was an abstract representation of Dorset's Jurassic coast.
It features giant impressions of marine life and algae made out of compressed foam and is covered with 350,000 resin coloured jewels, all applied by hand.
The exhibit offers something for all the senses, with a soundscape, LED screen and perfume which is sprayed on visitors intermittently.
Heywood, who spent a year making the installation with Alison Condie, said: "It looks very different to other gardens but was designed to reflect how we increasingly see nature in a more artificial way, through film and TV rather than in real life.
"We've tried to make everything exaggerated and cartoon-like, like the music which is a recording of sounds from the Dorset coast mixed with music from computer games.
"Everything you see and hear is half real, half artificial."
Smith and Heywood's exhibits are part of the show's Fresh area, a category introduced this year for innovative design and new ideas and concepts.
Deputy show manager Sarah Easter said she was impressed with the originality of some of this year's exhibitors.
She said: "They're always pushing the boundaries in terms of what's possible in the time. What they create in the timescale is incredible.
"We've seen a big trend in topiary at the show, which wasn't very expected. It's quite a traditional planting form which has made a comeback. We've an F1 car made of topiary."
She said the build-up to the five-day show had been the wettest for 100 years but should only make the plants look better.
"It's been very cold and very wet, it's been absolutely incredible. The rain has been very welcome, the show will look beautiful and lush.
"Last year it was so hot and dry we barely had any grass, this year it's going to look beautiful."
But she said the rain had led to muddy conditions at the site, meaning the show's team have been scraping off top layers of soil to give exhibitors a fresh surface to work on, while they have been pumping out puddles in exhibits.
Easter said many of the plants used every year were weather-dependent.
She added: "In terms of plants we have quite a lot of substitutions, designers all have back-up plants if they're not going to be ready in time for the show.
"Quite a lot of times, the gardeners will substitute their plants."