Audrey Cotton from Greenford, London, was presented with her moth orchid, which was bred in the Netherlands, at Wyevale's centre in Osterley.
She was nominated by close friend Sheila Slamaker for her fundraising efforts for local charities.
Garden centre manager Sarah Webb said: "Phalaenopsis 'Audrey Cotton' will be sold all over Europe.
"The judges chose Audrey's entry because of her commitment to the community and her dedication to helping others. Audrey has tirelessly raised funds for Ealing Hospital, Guide Dogs for the Blind and Meadow House Hospice in Ealing, London. We think she's a bit of a local hero."
Cotton is still a keen and active gardener. She has 12 grandchildren, 15 great-grandchildren and three great-great-grandchildren.
She said: "I am thrilled to have my very own orchid - it's beautiful."