Tribecan Marta Kuhn has had a children’s book brewing in the back of her mind for 15 years, even before she had kids — and when her second child was born, it finally bubbled to the surface. She just self-published “Schmoopie the Apple Lover,” a book for children 2 to 6 about a curious little square character from Planet Square Rock who discovers the magic of how things grow. (She will be at Laughing Man all week selling copies through June 5 and it’s on Amazon.)

The Schmoopies story — and this is one of more to come — is designed to teach kids about nature through playful discovery — apples lets the kids learn about seeds, soil, plants and the interconnected systems that support them.

“I was a full-time mom but I would sit there nursing thinking the whole time about this idea,” Marta said. “What is this world? What’s the message? How would people connect to it? What would it look like? It stayed with me for a long time.

“It’s teaching but not in a preachy way. It has to be about storytelling and experience.”

Marta worked at Estée Lauder for 10 years, starting in PR and ending up in the creative department, so she spent her time in story ideation and social media campaigns and ran the company’s online magazine. She loved it, she said, and after her first child, Karlie, she went back to work, but she soon realized she wanted to do something for herself.

She is producing and promoting the books entirely herself — the first run was 3000 copies.

“I thought there was a space for these kind of stories,” she said. “And once I had a kid, I thought this was the time — now or never.”

Marta, as she explains it, was an immigrant three times over. She was born in Russia and lived there until she was 6, when the family moved to Israel. They then moved to Romania for a before coming to the US — to Brooklyn — when Marta was 18. She never looked back — though she speaks to her children in Russian. (Her husband, Marcus, speaks to the kids in German. The couple’s second child, Leonie, is 1.)

She moved to Tribeca a decade ago, and uses Washington Market Park and Duane Park to develop ways to talk to kids about nature. “We call it treasure hunting,” she said. “It’s creating a world where kids discover the little things — which are in a way the biggest things.”

The next book will be about corals, then there’s one in the pipeline about the rain forest and after that, bees.

“At the center of it all, it’s really about care,” Marta said. “This one starts simple with apples but there’s a bigger lesson behind it. It’s a gentle gateway into talking about the power of nature.”