Walker using the idea of gardens in this essay?

Read In Search of Our Mothers’ Gardens

http://www.soulsvilleseniorenglish.com/uploads/3/9/1/2/39129857/walker-in_search_of_our_mothers_gardens.pdf

And answer question

.Walker titles her essay “In Search of Our Mothers’ Gardens, not of “My Mother’s Garden.” What does her mother have in common with all the mothers she writes about? Clearly, not all of these generations of mothers kept gardens. In what sense is Walker using the idea of gardens in this essay?