The garden was designed by charity volunteer Esra Parr, a Gold medal winner at RHS Hampton Court Palace Flower Show. She said her aim was for the garden to be a place of calm where people can remember their loved ones.
"The design is an abstract of the circular symbol for The Flower of Life, and the plants and colours have been chosen according to their meaning in various cultures. Some have an appropriate common name others have a meaningful variety name."
Missing Children's Day, on May 25, aims to raise awareness of the 140,000 children who go missing in the UK every year. Charity Missing People unveiled the commemorative flower garden at the London property.
The charity’s Missing People Choir, made up of people who have missing loved ones, alongside staff and supporters of the charity, performed at the opening.
Choir member Sarah Godwin from Godalming, Surrey, whose son Quentin has been missing since May 1992, said: "When you have a missing child it is so hard to find any moments of peace, or places where you can honour and think about them. The Find Every Child garden is a wonderful way to provide families like mine with a place to remember, while raising awareness of how and why the issue of missing children is so big".
Director of Chiswick House & Gardens Trust Clare O’Brien added: "We hope the missing people garden will be a place of refuge and solace for families and we welcome this beautiful addition to our Grade 1 listed landscape."