Elisa is caught in a world without the beauty she needs for fulfillment. Her husband focuses on the utilitarian worth of objects and efforts and doesn't know how to demonstrate the affection and emotional support that Elisa craves.
In the midst of htis unfulfilling situation, the source of pride and self-worth that Elisa can find for herself comes from her success in growing flowers in general and chrysanthemums in particular. Henry recognizes the exceptional size of the flowers but can't appreciate their aesthetic beauty or their importance to Elisa as an outlet for her yearning for attention.
"You've got a gift with things," Henry observed. "Some of those yellow chrysanthemums you had this year were ten inches across. I wish you'd work out in the orchard and raise some apples that big."
When the tinker comes, his description of his travels creates in Eliza a longing for the freedom to be able to come and go and find a different location that might be more fulfilling. She realizes she will never actually leave Henry, but the thought that her chrysanthemums might be appreciated and loved by someone in another location can serve as a substitute for the adventure she will never have.
I can put some in damp sand, and you can carry them right along with you. They'll take root in the pot if you keep them damp. And then she can transplant them.
The chrysanthemums symbolize hope for a better life - they always grow back, even after being cut off again and again.