One way in which setting is related to theme in "The Garden Party."

Katherine Mansfield closely ties setting to theme in “The Garden Party” as she highlights the sharp contrast between the upper and lower classes.
Mansfield describes the elaborate party plans for an afternoon of extravagance. The family speaks of trivial things such as hats, sandwiches, and songs as their servants prepare for the arrival of the guests. Everything is in overabundance, and clearly the Sheridans can afford to overspend, as evidenced by the lavish decorations. They give no thought to the significance of money but just spread it around without care. For instance, Mrs. Sheridan purchases a surplus of lilies to decorate the garden. She carelessly remarks, “for once in my life I shall have enough canna lilies. The garden party will be a good excuse.” There is no actual need for that many flowers, but she purchased them simply because she wanted them and she had the means to do so.
Mrs. Sheridan and Jose sum up the upper-class mentality toward the lower class. As she sits in her bedroom surrounded by expensive items, Mrs. Sheridan reacts nonchalantly to the accident once she confirms it does not involve anyone she knows. Her first reaction to hearing of a man’s death is, “Not in the garden?” When Laura replies no, her mother is relieved and continues looking at her hat. Human life is unimportant to her, unless it directly affects someone she cares about—someone in her class. When Laura, horrified at the tragedy, tries to call off the party, Jose tells her “Nobody expects us to” stop the party. Mansfield clearly depicts how the upper class is unfeeling toward the lower class.
Laura is the go-between of the two worlds, the conscience. Only she is affected by the tragedy, and only she suggests they bring food to the widow and children. Therefore, only she can actually make that journey—the others are too uninterested to bother.
The depiction of the widow’s house is a shocking opposite of Laura’s house. This is a real home, where people care for one another and real emotions show. The cottages in this neighborhood are described as an “eyesore, and they had no right to be in that neighbourhood at all.” In fact, the narrator describes the smoke coming from chimneys as “poverty-stricken.” Here, people speak “revolting language,” but their emotions are more genuine than those in Laura’s neighborhood. Laura is immediately welcomed into the “wretched little low kitchen” to pay her respects. She is quickly ushered into the bedroom by Em’s sister, who “fondly” shows her the body who “looks a picture.” The young man is described as peaceful; although he has died, he is surrounded by the ones he loves. This poverty-stricken environment is a true home, in sharp contrast to the feigned caring of the wealthy household.