They have been part of American horticulture — and culture — for nearly 150 years, yet Japanese gardens remain a mystery for many people.

That doesn’t have to be the case. According to Tim Gruner, the garden curator/head of horticulture at Anderson Japanese Gardens in Rockford, Ill., you start with the intent of a Japanese garden: evoking a feeling.

"A Japanese garden seeks to create the emotional response to nature in any space," said Gruner, who oversees one of the country’s pre-eminent examples of the aesthetic. "So the feeling you get standing in a place of great natural beauty, the positive emotions and reactions to that (the question is), how can you create that kind of emotional response to nature in your backyard?"

For some, a garden means a patch of zinnias here, some marigolds there, a couple of rose bushes and a little groundcover. All well and good and pleasing to the eye. The Japanese garden follows the dictates of nature.

That was one of the purposes of the first Japanese gardens in the U.S. They were introduced to the public here in 1876, at the Centennial International Exhibition in Philadelphia. America was becoming more urbanized, and there was a desire to bring nature to people in cities. And the cities liked the gardens for what they projected.

"Industrial cities wanted Japanese gardens as a kind of sign of cultural attainment," says Kendall Brown, president of the board of directors of the North American Japanese Garden Association.

Even today, Japanese gardens are constructed around guidelines and ideas that date back more than a thousand years.

"The Japanese garden is based on natural patterns, rock formations, the way plants grow naturally, the way water moves naturally through a stream valley. The shape of the land," Gruner explained.

"A Western garden — and this is a gross generalization — is often symmetrical, geometrical, versus the asymmetrical Japanese garden. Think of classic gardens like Versailles, totally fabricated patterns laid out on a grand scale across an obviously human-controlled environment. A Japanese garden is asymmetrical, natural-plant oriented; some areas evoke the essence of a forest or stream valley or wetland, some evoke the feeling of rolling hills."

David Slawson, a noted garden designer and scholar whose 1987 book "Secret Teachings in the Art of Japanese Gardens" is considered a classic, explored the topic in his 2012 DVD, "Evoking Native Landscape Using Japanese Garden Principles."

"One of the striking differences between Japanese gardens and most Western gardens," he says, "is the Japanese use of plants to evoke their habitat in nature versus the Western use of plants purely for their decorative qualities."

HOW DO you know if a Japanese garden is for you? Gruner says to do your research. In addition to the works of Slawson, a good source is Sukiya Living magazine, which publishes six times a year and focuses on Japanese gardens and architecture. It can be ordered at www.rothteien.com, a website that also features sample articles and information on workshops and tours. Also, the North American Japanese Garden Association (www.najga.org) is working hard to promote the building and care of gardens.

Gruner and Slawson also suggest exploring other gardens and nature to see what moves you.

"I encourage people to visit nice examples (of Japanese gardens)," Gruner said. "Visit great natural spaces and try to figure out what kind of scenes mean the most to you and make you feel something. If you have a space that allows it, create a space that evokes the parts of the natural world you really connect with."

Slawson takes his students on field trips.

"Usually I have each person sit by themselves. Find something they respond to. Do a sketch," Slawson said. "That’s one of the best ways to get in touch. Photography is great, but that mechanism is putting us at a distance. So much of this is about opening ourselves up to the experience. … Instead of putting our imprints on things, it’s all about allowing nature to speak."

The basics in building a garden are rocks, water and plants. The latter is no problem; they’re available everywhere.

And so are experts who can help build water features. But should that be impossible, there’s always the dry landscape, where stones and pebbles are installed in patterns to create the visual energy of moving water. The Anderson Gardens website notes secondary elements, which include pagodas, stone lanterns, water basins, arbors and bridges.

Careful setting of plants can also create an illusion. In his DVD, for example, Slawson shows how he varies the sizes of plants to change perspectives.

Light-colored plants and large plants are in the front, dark and smaller ones are in the distance, he says. The result is a sense of depth.

There is, no doubt, a lot of planning and physical work involved.

Gruner said that "people who are driven and interested in exploring and who have a strong back can do it on their own."

But there are pros out there, such as Slawson, who can work magic.

He had a client who had a 6-by-10-foot plate-glass window installed instead of a fireplace so he could look at the garden, which Slawson likens to a work of art.

"Look at a landscape painting … that is the effect you want to create," he said. "You want a whole experience. … You want not to feel like human interaction or ideas were involved, but that it came together naturally without human forces."