As the designer for horticultural therapy charity Thrive this year, she has focused on a "masculine" palette of purples, browns and lime greens. The entry, called The Unexpected Gardener, is designed for a mature but stylish male gardener.
It chimes with Thrive's focus on using gardening to help transform people's lives, explains Thompson, as well as her own personal experiences. "My dad is in his 70s now and he is finding it a bit harder to get around, but it doesn't mean his garden must be all about that," she says.
Thompson's involvement with Thrive stemmed from a meeting with one of the charity's trustees, garden designer Andrew Fisher Tomlin, during last year's Chelsea Flower Show, where she had created a garden for children's charity Demelza.
"On the last day of the show I was feeling a bit depressed, seeing this baby you have conceived and created being ripped apart," she remembers. "I had a bit of a wander around and went to chat to Andrew (Fisher Tomlin) and he started telling me about Thrive."
As the spark of an idea for a Chelsea garden began to develop, Thompson went to visit one of the charity's sites in Reading. "I didn't know what to expect, but the thing that got me was seeing people pruning and cutting hedges who were blind," she explains. "That is a job I shirk and think I can't do. It was a real leveller."
The multi-lingual designer appears to be magnetically drawn towards career challenges, a feature that has its roots in her university days, when she learned to speak Italian in two weeks in order to bag a degree place.
Although Thompson turned to garden design after a career in teaching, she likens the profession to drama, which she taught for many years. "Garden design is like putting on a creative show - it ties in with the stage management of drama," she explains.
Born of Italian descent, Thompson's earliest memories feature holidays spent in the Mediterranean hills. "I was taken by the Italian gardens," she recalls. "There aren't many flowers, but it's the villas, the architecture and the strong lines."
Thompson cannot restrain herself from including at least one beautifully intricate element in her Thrive garden. The ambitious installation is a stone and acrylic water design, containing hundreds of elaborate layers. Hoping to score innovation points, she acknowledges that the design has never before been used at Chelsea.
"I decide that I want to do something and then do it. That's the story of my life," she proclaims. Thompson adds that the key to garden success is team work and building strong relationships with her contractor, who this year will be Richard Penfold of New Ground Landscapes.
Nevertheless, she reveals her strong personality and ability to dictate affairs can pain those working alongside her. "Last year one gardener locked me in the van," she laughs.
With trees sourced from Hillier Nurseries and plants from Roger Platts, Thompson has gathered a well-renowned team around her. She has chosen two multi-stem four-metre Prunus serrula trees as focal points for her garden, but she admits that there was a hiccup when she realised her plot was facing the opposite way to her original design, which "means switching everything around".
An Iris 'Jamie Roo', grown by Brian Hersey and not shown at Chelsea before, will appear in the garden along with plants from Iris of Sissinghurst. Jekka McVicar is growing herbs, while other plants are being grown by Thrive's clients at its Battersea site, a stone's throw from the Chelsea site.
The garden will be dismantled and rebuilt for Thrive after the show, at which point Thompson will be well into the creation of a garden for another client. She is working on a garden at the Peter De Haan Charitable Trust that will also be used by the National Youth Theatre and London Wildlife Trust.
But, like many garden designers, her own plot leaves something to be desired. "My own garden is absolutely tiny and a bit of a wreck," she admits. "I would seriously love to have the Chelsea garden at my house, although the children would hate it because there is nowhere to kick a ball."
As the last few weeks before Chelsea ebb away, Thompson waves away any feelings of pressure, instead focusing on the relentless health and safety forms. The tension of producing a Chelsea garden appears to suit Thompson's personality though, and she reveals: "Walking into the build last year, I felt I had found my tribe."
1985-89: Studied Italian and French at UCL
1989: Worked for FIAT and Jasper Conran menswear
1990: Started PhD in early Italian cinema at University of Cambridge
1991-92: Completed post graduate certificate in education
1992-99: Primary school teacher
2000-03: Full-time mother
2003: Studied at English Gardening School
2004: Set up design practice
2009: Demelza garden at RHS Chelsea Flower Show
2010: Thrive garden at RHS Chelsea Flower Show