Lessing's grasp of political themes is evident throughout The Grass Is Singing, particularly through her depiction of characters that represent various elements of farming in developing countries during the early 1900s. Although Charlie Slatter is portrayed as the successful farmer who ultimately gains control of the land, he fails to earn the readers' sympathy. In contrast, Dick Turner is portrayed as a tragic character who evokes empathy because he not only dreams of owning the land but also connects his self-worth to it. Both men, like all white farmers of their time and region, are limited by their oppressive exploitation of native workers.

Even though Dick Turner treats the natives relatively humanely, his wife's actions worsen the injustices. Unaccustomed to farm life and working with natives, Mary Turner enters her marriage only to realize her dislike for farming and the presence of the natives. Dick's inability to address his wife's treatment of the natives reflects both their marital problems and the ongoing perpetuation of injustice.

Lessing further highlights the social hierarchy within this farming community by illustrating how other farmers are invested in the Turners' increasing poverty. When Charlie encourages Dick to leave the farm, the narrator explains that Charlie:

was fighting to prevent another recruit from joining the growing army of poor whites, who appear so much more shocking to respectable white people (though not pitiful, as they are despised and hated for betraying white standards, rather than pitied) than all the millions of black people confined to slums or shrinking land reserves in their own country.

Because the Turners do not align with the group's values and priorities, their neighbors withhold support.

The novel frequently presents a fatalistic outlook, indicating that no matter one's ambitions or desires, people are eventually overwhelmed by societal expectations. Straying from these norms often leads to despair and personal collapse. The pressures of society can frequently induce mental breakdowns, as Marston muses, "What is madness but a refuge, a retreating from the world?"

Mary's late understanding that she has ended up in the same situation as her mother only amplifies the sense of hopelessness and alienation between them. As the gap in their marriage expands and they vie for control, Mary hides the shifting dynamics between herself and Moses, especially as the vague sexual tension grows stronger.

Throughout the story, Lessing skillfully incorporates imagery from T. S. Eliot's The Waste Land, which she references at the start of her book. This imagery becomes particularly noticeable in the concluding chapters as Mary becomes isolated from those around her and withdraws into her dreamscape. Despite the oppressive heat and the relentless noise of cicadas serving as constant reminders of nature's intrusion on her land, Mary's senses grow sharper as she experiences personal unraveling. Her dreams are dominated by vivid imagery, filling "her mind with green, wet branches, thick wet grassland thrusting bushes." Just as Mary is helpless to prevent the veld's grass and bush from encroaching on her home, Dick considers taking control by burning the grass on their last day at the farm as they prepare to leave. Ultimately, in a tragic turn, Mary recognizes her errors and accepts her inevitable downfall.