Chalk it up to the city's crackdown on graffiti.

A 6-year-old child's chalk sketches on her family's stoop brought her bemused parents a graffiti-removal notice that threatened a $300 fine, the family and Sanitation Department officials said.

"My mom got a ticket for graffiti, and it wasn't even graffiti," first-grader Natalie Shea said. "It was art, very nice art."

But a neighbor apparently didn't see it that way and called the city's 311 complaint line about the blue flower drawn earlier this month on the stoop of Natalie's home in Park Slope, a Brooklyn neighborhood known for being family-friendly.

The notice that arrived Oct. 5 — giving the family 45 days to clean up the "graffiti" — was a form letter sent in response to all such complaints, city Sanitation Department spokeswoman Kathy Dawkins said.

"If people call and complain, we have to follow it up," she said, but noted that the agency "does not consider a child's chalk drawing to be graffiti."

Nor does City Councilman Peter Vallone, who spearheaded a 2005 city law that requires property owners to get rid of graffiti.

"It was never the intent of my law to capture chalk drawings on the sidewalk," he said.

Natalie's mother, Jen Pepperman, said she would wash off the girl's doodles more promptly in future. As for the offending flower, it was erased Thursday by a heavy rain.