A 2-year-old botanical garden nestled off the beaten track on Pine Mountain Road in Kennesaw is gaining attention from horticulture groups and the public.

The 16 acre Smith-Gilbert Gardens has more than 3,000 plants, including the state’s only public bonsai collection. The former private estate has evolved into a place for gardening classes and family outings, and is a popular wedding site.

The American Rose Society has put the property on its must-see list of private and public gardens in the United States. The Southeastern American Conifer Society recently gave a $1,500 grant recognizing Smith-Gilbert’s conifer collection.

The garden has 97 varieties of roses, 86 conifer species, 1,000 annuals and 30 pieces of contemporary sculpture purchased by the former owners. Executive Director Doug Davis said 150 volunteers do the lion’s share of upkeep.

Rodney Clemmons, a bonsai master who takes care of the garden’s 60 dwarf trees, said Smith-Gilbert has the potential to become one of the outstanding bonsai collections in the country. Clemmons also leads a monthly bonsai study group that includes Cobb Superior Court Senior Judge Michael Stoddard.

“I hope people will support this place and what it offers,” Stoddard said. “The gardens are a hidden gem in the forest.”

On a recent muggy afternoon the judge led a Kennesaw family through the bonsai garden.

Jennifer and Bernard Nolan brought their three young sons on their first trip, which included a picnic and a lesson on bonsai trees.

Bernard Nolan said he’d seen the Smith-Gilbert sign many times but had no idea how extensive and well thought out the property was.

“I’d much rather have us walk around wide open spaces than in a mall,” Nolan said. “This is good for the boys.”

The city of Kennesaw bought the property from Dr. Bob Gilbert in 2005 for $2 million with funds from a $12 million parks and recreation bond.

Smith-Gilbert has a $267,000 annual budget, with 20 percent coming from donors.

Gilbert and Richard Smith started cultivating the property in 1970. They surrounded their 1880s home, which now houses the property’s offices and library, with a series of woodland and meadow gardens.

They also added a habitat for birds, a rock garden and a Japanese tea house overlooking a koi pond and waterfall.

After Smith died in 2002, Gilbert worried the property would be subdivided and the gardens bulldozed if he sold to an individual.

He decided to offer the property to Kennesaw to preserve it.

Although Gilbert moved to North Carolina two years ago, he visits his former home once a month for bonsai study group meetings.

“I’m impressed with the way the place is maintained,” Gilbert said. “There is enthusiasm from the public and it all seems to be working.”

Davis said the garden is essentially how it was developed by the former owners.

What’s new are rose and camellia gardens, and there are plans to build an event facility with parking access.

A carriage house on the property is used for receptions and meetings.

The gardens are not formal or intimidating, the director said. The goal is to offer a natural setting where the public will feel comfortable.

“We want to keep the spirit of the gardens intact,” Davis said. “This is also a great place to sit and read a book, to be serene.”