The third chapter begins by introducing Martha Sowerby, Mary's new maidservant. Martha, however, hardly thinks of herself as a servant, as rapidly becomes clear: she expects Mary to dress and feed herself, and is not at all deferential. Mary becomes irritated in comparing Martha's liberal manner with that of her servants in India, whom she treated as less than human. The typical Yorkshire bluntness of both Martha and the gardener Ben Weatherstaff begin to alter Mary for the better in this chapter.

Both Mary and Martha here evince extreme racism, made the more disturbing by its casualness and by the novel's implicit endorsement of it: Martha remarks that Mary's awfulness may be because she is from India, where there are "a lot of blacks instead of respectable white people." Mary, in her fury at being assumed to be black, shouts, "Natives are not people." A painfully obvious symbol of this racism can be found in the replacement of the black clothes Mary arrived from India in by white ones, as well as by her attendant statement that she "hates black things"; the reader is given to understand that Mary's life in England will be everywhere marked by whiteness rather than despised blackness.

Misselthwaite Manor, however, has its own form of "native": all the servants speak Yorkshire dialect, which marks them as different from the inhabitants of the manor, and which Mary can barely understand. Martha's impoverished Yorkshire family is presented as being in almost uncanny harmony with the land: the hungry children are said to eat moor grass, as though they themselves were wild animals. The poor—particularly Dickon, Martha's wondrous brother—are depicted throughout the book as being more natural, unspoiled, and simple than the residents of the manor, and provides one of the novel's central oppositions. This, of course, is hardly unique to The Secret Garden. The poor, so frequently barred from education, are then hypocritically celebrated by the wealthy for their refreshing lack of "civilization."

It is now winter in England, which means nothing is growing upon the moor. The landscape mirrors Mary's state of well-being throughout the novel: at this point, she is still miserable and friendless, and so the moor itself remains bleak and barren. The secret garden, first mentioned in this chapter, is also implicitly aligned with Mary: it has been locked for ten years, and Mary is precisely ten years old. It remains locked here because Mary herself is still closed off from all human congress and friendship.

Mary is also aligned with the robin redbreast in this chapter: like her, he began life as an orphan; he lives in the secret garden, as she would like to; like her, he began to seek out friendship when he realized he was lonely. The friendliness of the little bird both helps Mary recognize that she is lonely and to assuage that loneliness. This is significant in that Mary is awakened by a wild creature, a distinctive part of the English countryside; the robin is explicitly described as being "not at all like birds in India." The landscape (of which the robin and Dickon Sowerby are a part) is here foreshadowed as the agent of Mary's eventual transformation.