He claims it is because the tree is sick.
Nathan Radley tells Jem and Scout that he filled the knot-hole with cement because the tree was dying and he didn't want it to fall on someone. However, it is later revealed that he filled it to prevent gifts being left for the children by Boo Radley.
Mr. Radley puts cement in the knothole to prevent any further communication or interaction between Boo Radley and the children. This action is driven by his desire to isolate Boo Radley from the outside world.
Nathan Radley tells the children he sealed the knothole with cement in order to prevent Boo Radley from communicating with them or giving them gifts. He likely did this to further isolate Boo and maintain control over his actions.
Nathan Radley knows Boo has been leaving gifts there for the children so fills the hole in with cement. When the children enquire as to why he's doing this, he lies and says that the tree was dying and this would save it.
Scout says that the Radley place had ceased to terrify her because she has learned to see things from Boo Radley's perspective, and she now understands that he is not a malevolent figure. Through her experiences and growing maturity, Scout has gained empathy and compassion for Boo, which has helped her overcome her fear of the unknown.
Jem and Dill hatch a plan to leave a note for Boo in the Radley's window, using a fishing line. The note will ask him to come out sometimes and tell them what he's doing inside, and that they won't hurt him and will buy him ice cream. Dill says he wants Boo to come out and sit with them for a while, as it might make the man feel better.
nathan sykes' fave colour is pink!! it says on their website :)
Mr. Nathan Radley knows about the intruders in his garden because he is vigilant and likely noticed the disturbance. Miss Stephanie knows about the intruders because she is an active member of the neighborhood and probably heard about it through gossip or conversation with others.
He doesn't want Atticus to return the blanket because he realizes that Boo cares about them and he is trying to be nice. Boo also hasn't been seen in a while and people seeing him could upset him.
Jem says that Boo Radley must not be at home because he's never seen him before. The irony is that Boo Radley has been watching over Jem and Scout all along, and cares for them even though they are not aware of his presence.
Scout means that Mr. Radley made a financial investment in cotton, which was a common crop grown in the Southern United States during that time period. She is referring to Mr. Radley's involvement in the agricultural industry.
Atticus says this because Jem and Scout trespassed and disrupted the peace at the Radley Place, which is a serious offense. He believes that they should respect others' property and privacy, regardless of their curiosity about Boo Radley.