The petition, started by her son, has gathered more than 190 signatures.
Katharine, a retired teacher who has lived in the area since the 1960s, said the garden gave her a reason to go outside.
“This space is important to me because I love gardening and it gives me plenty to do. I need an occupation in my retirement,” she said.
“People come up and talk to me while I’m doing it, so it gives me a bit of a social life as well.”
She said she had never seen anti-social behaviour at the site and disputed that the pots obstructed the pavement. She uses a walking frame and said she was able to pass them freely.
Her neighbour Holly Bell-Stevens said the corner would lose its character if the pots went.
“We have this quiet oasis within the City of Westminster, and removing the pots means it would just become another concrete corner,” she said.
“My children learned how to ride their bikes in this corner. We walk our dogs here. It cultivates a community and it touches everyone.”