Why is Anya angry with Meredith's cleaning of the winter garden in the novel, Winter Garden?

For Anya, the winter garden is a symbol of the past. She spends a good deal of her time in the garden, even when the temperatures are below freezing. Meredith believes that she is doing her mother a favor when she cleans out the garden and plants new flower seeds. Instead, Anya is angry with her daughter. Meredith later realizes that the garden represents Anya’s relationship with Sasha and Leo, and that her act of cleaning out the things her mother had planted there was like the desecration of a grave.