Steve and Pauline Danielson were vacationing in Hawaii when they first saw the Fern Grotto, a naturally formed lava cave dripping in ferns and encircled by lush tropical plants. The tourist attraction was made famous in the Elvis Presley movie “Blue Hawaii.” The Danielsons were awestruck.

Steve promised Pauline that he would bring a taste of Hawaii to their Maplewood yard by building his own version of the Kauai grotto when they got home.

Today the Danielsons’ secret hidden “grotto” seduces visitors with the sound of water cascading down to colorful river rock below.

Massive banana trees, water cannas and showy taro give the setting a tropical jungle vibe.

“I dry-stacked slate to create a concave-like shape to make it feel like a grotto,” said Steve, who dug and built the 6-foot-tall structure himself.

The Danielsons’ gardenscapes are one of 11 sites highlighting koi ponds, waterfalls, streams and even a waterwheel on this year’s Minnesota Water Garden Society tour, July 28-29.

Novice and experienced gardeners can get tips from “pond-ers” on choosing plants, and building and maintaining different sizes and styles of water features.

Steve will share his expertise on everything from constructing his 3,000-gallon backyard pond to low-maintenance pondless waterfalls, which he installed in his grotto.

His yard is also packed with examples of how to design and plant a naturalistic landscape that mimics nature.

“I mix contrasting textures, different sizes and colors of hardy perennials, trees and shrubs with the water plants to give it a natural feel,” he said.

Have a tiny yard or just a patio? Find out how easy it is to plant a container water garden — one that never has to be watered.

The Danielsons placed a homemade bubbler in a large planter filled with water canna, blue flag iris, golden club and parrot’s feather.

“We don’t want people to copy us,” said Pauline, “but be inspired by what we’ve done and make their own version.”

The creative DIY couple have been plotting, planting and tending their lush eye- and ear-soothing gardens for more than two decades. Their gardens range from shady woodland beds to picturesque ponds and streams.

“We bought a house with a blank slate — so I could start fresh and create my own style,” said Steve. That style is more about composition, form and texture than it is about color. “A garden should look good even when it’s not in bloom.”

The soothing sound of water also drove the placement and choice of plantings around several of their multitiered water features.

Two mini-waterfalls flow into a stream, which cascades down to the main backyard pond. “You don’t see the first waterfall, but you can hear it,” said Steve. “It creates mystery and intrigue,” added Pauline, as she fed goldfish darting among the waterlilies. They use an aerator to keep the pond from freezing so the two dozen fish can live there all winter.

Water irises and petunias sprout from the surface, and brooklime creeps across a waterfall. A mugo pine and exotic water lotus add an Asian flair to the serene oasis.

The Danielsons have also installed nightlights — from low-voltage tulip-shaped lights lining pathways to candlelights dangling from trees — to illuminate the gardens after dark. “Nightscape” viewing is the Pond and Garden tour’s newest attraction.

“It takes on a different look and feel, and creates a romantic mood,” said Steve.

But water gardening is still the couple’s true passion. After all their hard work, they’re rewarded with the tranquil sound of flowing water from every room in their house.

“It’s moving all the time, like a nice breeze across ornamental grasses,” said Steve.

@LyUnderwood