According to Jem, what does the phrase "he bought cotton" mean in To Kill a Mockingbird?
As Scout explains, undoubtedly realizing her readers would have no idea what the term alludes to, it means doing nothing. It's a euphemism for saying that Mr. Radley, at least as far as the children know, didn't work for a living. The origin of the term is obscure. It's obviously a regional Southern phrase that alludes to cotton, an important cash crop in the South. Various web sites explain that it means that Mr. Radley—or anybody who didn't work—would have bought rather than labored to make their own cotton cloth. That would imply having the independent income to do such buying. It might also mean he said he spent his time speculating in the commodities (cotton) market, but really he did nothing, just as today we might say "he buys stock" or "he's working on his novel."
In any case, the important point is that it indicates the children can't "place" Mr. Radley easily in the social hierarchy of Maycomb. Without a known job, Mr. Radley has no fixed, identifiable place in the community.
Jem says that Mr. Radley “bought cotton” because he does nothing.
The Radleys are the mystery of the block. They are very reclusive people, and rarely interact with others. The children are fascinated with Boo Radley, who seems to be so reclusive he never leaves the house.
I never knew how old Mr. Radley made his living- Jem said he "bought cotton," a polite term for doing nothing… (ch 1)
Mr. Radley apparently just walks to town once a day to buy groceries and only stays out for a half an hour. The mystery of the Radleys is too much for Scout and Jem. They come up with a variety of stories about the family, especially Boo.