My bookshelves are filled with guides to gardening. There’s a book about container gardens, another about topiary, a few on kitchen gardens and one on family gardening, whatever that is.

Roses, perennials, native plants — I have books on every topic. But “Mister Owita’s Guide to Gardening” stands apart because rather than share how-to tips (there aren’t any), the author shares spiritual lessons with readers.

Carol Wall wrote “Mister Owita’s Guide to Gardening: How I Learned the Unexpected Joy of a Green Thumb and an Open Heart” before she died from complications of breast cancer in December 2014.

Her husband, Dick Wall, promised his wife that he would carry her legacy forward, and he has been touring for the past six months to promote the book.

“The book is more than anything a book about living,” Dick Wall said. “Carol’s experience with Giles (Owita) helped her rediscover optimism when she was battling breast cancer. He would say, ‘Everyday brings something good,’ and it’s a philosophy that Carol took to heart.

“She knew what the prognosis was, but she remained determined to live fully.”

Carol Wall was a self-confessed garden curmudgeon with an aversion to flowers when she first met Owita, from Kenya, whom she hired largely out of embarrassment about the appearance of her front yard.

For their initial meeting, she made a list of chores for Owita to perform, determined to rid her yard of azaleas and establish a sense of order.

She quickly learned that Owita had his own plans, which included keeping the azaleas and planting bulbs that would burst forth in the spring as a wonderful surprise.

In the course of the developing friendship and landscape, Wall found herself letting go of her preconceived ideas about gardens — and people — and embracing the openness and optimism that Owita brought to her life.

Even after Owita dies toward the end of the book, Wall carries on by deepening her friendship with his wife, Bienta.

“Somewhere in the book, Carol says that she and I belonged to a club that no one wanted to join — a club of people who knew serious illness and loss. But since I have been on the road with the book, I’ve learned that it’s actually a pretty big club,” Dick Wall said.

“Readers ask me, ‘Isn’t it hard to talk about it?’ But when you have a personal loss, it doesn’t mean your life is going to be terrible. It just means it’s going to be a whole lot different.”

In tribute to Carol Wall, the couple’s youngest son, a filmmaker, joined his father on the book tour for a few weeks, shooting film in preparation for a documentary.

Dick Wall has continued his wife’s friendship with Owita’s widow, who has accompanied him at several book signings that were held close to the family’s Virginia home.

And the “garden of Eden” that Owita transformed from what Carol Wall called “a wasteland” is still thriving, filled with “good looking flowers,” according to Dick Wall.

In a short video on Carol Wall’s website, the author talks about her life-altering friendship with Owita and describes the spiritual journey they undertook together. She crystallizes the essence of the book when she says, “What do you do when the script you wrote for your life doesn’t work out? How do you graciously slip into Plan B? It was Giles who traveled 7,000 miles to teach me that the ground in winter … holds a thousand lovely secrets.”