Stuart Reynolds forgot he had agreed to look after his grandchildren and drank nine pints of lager before his son-in-law collected him and drove him to Manton, Worksop, on June 26.
Prosecutor Daniel Pietryka said: “There was a disagreement because they said he was in drink. He was given some of his clothing in a laundry basket and he set fire to it.
“In police interview, he said he was sick of carrying the clothes around. He said he was sorry for what he had done.”
The court heard his grandchild’s toy scooter was melted in the blaze, and £100 of damage was caused to a glass door.
Reynolds, who was unrepresented, said: “On the day in question I had completely forgotten I was supposed to be babysitting.
“My daughter realised immediately that I had had a drink and she exploded quite furiously.”
When she threw a laundry basket of his clothes and some of his shoes at him, Reynolds put them into a “neat pile in the middle of the garden and set fire to them.”
He told the court that although he was working, he was also homeless.
He spent some time at his partner’s house, would get a bed and breakfast when he could afford it, and “sleeps rough once or twice a week” he said.
Reynolds, 55, admitted arson and criminal damage, when he appeared at Mansfield Magistrates Court, on Wednesday.
District judge Jonathan Taaffe said: “The risk to life and limb to your nearest and dearest means that this passes the custody threshold.”
He handed Reynolds a 16 week prison sentence, suspended for two years, and ordered him to pay £100 compensation, £85 court costs, and a £115 government surcharge.
“It doesn’t take a rocket scientist to know there’s a drink problem here,” he told Reynolds.
“It strikes me that drink is ruining your life and you having a meaningful relationship with your family and grandchildren.”