Lee and Jerry Shannon have evolved as gardeners as dramatically as their landscape has been transformed by their efforts. More than 40 years ago, the couple inherited some back-yard perennial beds and weren't quite sure what was a weed and what was a coneflower.

But their eagerness to learn and a deep love for growing helped them transform their two-thirds of an acre in St. Paul into a sumptuous setting worthy of countless garden tours and even a brief starring role on a 1990s HGTV show.

The Shannons' mission to keep gardening interesting for themselves, year after year, led to the creation of a formal English garden, rock gardens featuring hardy cactuses and alpine plants and even a before-its-time rooftop garden.

But what sets the Shannons apart from average gardeners is their tireless hunt for trees, shrubs and perennials that aren't typically cultivated in Minnesota landscapes.

"I'm not that interested in plants that are a dime a dozen," said Jerry. "I want what no one else has."

Most visitors to their glorious, ever-changing gardens would never notice that they include such hard-to-find specimens as a Finnish hybrid rhododendron and a bladdernut shrub.

But it's clear, even to a casual observer, that the garden belongs to someone with an expert eye for design and a thorough knowledge of plants.

"I call it a collector's garden," said Jerry. "We collect plants like people collect antiques and stamps."

Garden greenhorns

When the Shannons bought their house in 1967, their garden experience was limited to growing vegetables. Lee had helped her family tend the beds on their Wisconsin hobby farm, while Jerry and his dad had cultivated a Victory Garden in St. Paul during World War II. "We grew up with the philosophy that if you couldn't eat it, you didn't grow it," said Jerry.

That ideal would soon change. "First we had to learn how to identify the flowers," said Lee, referring to the previous owner's hodgepodge of plantings.

The couple quickly started networking with experienced gardeners by joining local clubs, such as the Garden Club of Ramsey County, the Minnesota Horticultural Society and the Men's Garden Club. (They remain active members of many gardening organizations.) And as educators for the St. Paul public schools, both had summers off to devote to their newfound hobby.

Over time, they expanded and widened their original perennial gardens, which now boast a seasonal succession of flowers from bulbs in early April to witch hazel in late November.

"When the Adonis blooms in April, we know the frost is out of the ground and it's time to get the mulch off the beds," said Jerry. And time to work from sunup to sundown until mid-June.

"We don't need to belong to a gym," said Jerry. "The garden is our health club."

Each growing season, they change up their plant combinations. For example, they replaced what Lee called a "boring ribbon of pink begonias" with tropical piggyback plant and colorful ornamental peppers. "We don't grow them to eat, just for their interest," said Lee.

Winter discoveries

After the Shannons put their gardens to bed, they focus their energy on garden research. Not via computer -- they don't own one. Instead, they relish poring through the books and journals at the University of Minnesota Landscape Arboretum Library throughout the winter.

"I like to look up gardens from around the world and see what's growing in Zone 4 to find plants that would be winter-hardy here," said Jerry.

That's how he found the Finnish hybrid rhododendron developed at the University of Helsinki, which he bought from a private grower because it was unavailable at Minnesota nurseries.

"The pink flowers are bigger than what you typically see in Minnesota, and it stays green all winter long," he said.

Many of the plants they've discovered through research aren't available at local nurseries, so they've joined five plant societies from around the world to participate in seed exchanges.

They were able to grow an Amur maackia from China and a climbing purple monkshood, using seeds from their global network. "When I asked for the monkshood at local nurseries, they just rolled their eyes," said Lee.

New land

The Shannons' desire to try new varieties led to overplanted gardens, they admit. So in the 1980s, they jumped on the opportunity to buy more land adjoining their property, and hired a landscape designer to shape the new beds and install a cement walking path.

Then the Shannons were able to re-create what they had admired during their travels in England and the East Coast: a formal garden of tidy boxwood hedges.

"It all started from two boxwood rooted cuttings from Dr. Leon Snyder, the first director of the Minnesota Landscape Arboretum," said Jerry. For splashes of color, they planted shrub roses and hybrid teas in the center of the trimmed boxwood.

With the added land, they also created four rock gardens of hardy native cactus and diminutive alpine plants, which are Lee's current passion. She's even planted dwarf iris, yellow poppies and dianthus among rocks she's collected inside 25 Styrofoam troughs, which are displayed in the front and back yards. "They're so cute and so much fun," she said.

After four decades, the Shannons are done digging and expanding the beds, but they'll continue trying unique new plants in place of expired ones.

Lee will grow varieties of dwarf alpine plants from seed this winter, and Jerry plans to plant a different variety of Finnish hybrid rhododendron this spring.

"We feel our garden is healing for the body and soul," said Jerry. "We get our exercise, we have visual beauty and we eat the vegetables all winter long."

Lynn Underwood • 612-673-7619