After 42 years of gardening a difficult 1.3-acre parcel in Bedford — a seasonal creek cuts it in half and the adjoining Mianus River regularly floods large portions of her backyard garden — Cheryl Thomsen has learned what works and what she shouldn’t even think about growing.
Instead of using beds brimming with colorful annuals and perennials, Thomsen has chosen to work with stone and a simple palette of greens.

“Between the muskrats and the water, I’ve gone with a few old standbys,” she says, including astilbes, catmint, hostas, pachysandra, boxwood, rhododendron, spruce, hemlock, arborvitae and birch and maple trees.

A rhododendron in bloom:

“I have a lot of different textures going on,” she says. “The interest comes from conifers and broad-leafed evergreens.”

On Saturday, Thomsen will open her garden to the public as part of “Rhapsody in Bloom,” the annual Girl Scouts garden tour. Seven other private gardens in northern Westchester will be open that day from 10 a.m. to 4 p.m. along with Bylane Farm, the home of the Bedford Audubon Society.

Here’s a video by Tania Savayan, with Cheryl and Ann Marie Imbriale, special-events manager for Girl Scouts Heart of the Hudson:

Behind the scenes, with Tania:

Tickets for the self-guided tour cost $40, or $65 with lunch. All proceeds go to Scouting programs run by Girl Scouts Heart of the Hudson, which serves 31,000 girls and 15,000 adult volunteers in Westchester, Putnam, Rockland, Orange, Sullivan, Ulster and Dutchess counties. Its central office is in Pleasantville. New this year is a courtesy child-care option for tourgoers with children ages 4 and above; preregistration is required.

Attendance will be limited and tickets will be sold on a first come, first served basis, Imbriale says. In the past, attendance has been as high as 400, and she hopes for a turnout of 250 to 300 this year.

“Traditionally, we raise about $20,000 every year, in that range,” she says. “What’s amazing about Cheryl’s garden is that she did all the work herself.”

That includes building fences, moving the driveway, mowing the lawn with a tractor, laying stone pathways, crisply edging all of the meandering beds, filling in swampland and hand-pruning nearly all of the shrubs. She hires a helper to work with the big stones and maintain the huge yew and hemlock hedges.

She keeps plants in her urns for two years, then puts them in the ground.

Thomsen is one of those great natural gardeners with an innate sense of scale, design and color.

She’s completely self-taught and quite passionate about gardening. Long before Google and the Internet, she found herself devouring every garden book she could get her hands on.

“This is my classroom right here,” she says, standing on the stone patio of her 1920s clapboard house, one arm sweeping out to a verdant sea of green. “I know the plant material, I know the diseases they get, I know what works and what doesn’t.”

An old chicken coop:

She took one continuing-education class at the New York Botanical Garden a few years ago and realized she knew all this stuff already. “The teacher had me teach the last class,” she says with a laugh.

Four years ago, she decided to launch her own landscape design business. Called Gardentales, it’s been a great success — lots of clients and word-of-mouth referrals that keep her busy most of the year. She also runs a dog-grooming business — that may explain her talent with gardening shears.

Have you ever seen better clipped boxwoods??

For her own garden, Thomsen has chosen no-fuss plants that can take a good bit of abuse.

She created beds of easy-care pachysandra with cuttings from her mother’s garden. “I would bring up bags of it, then be on my knees for days and days.”

“For the back of the property, I had to choose plant material that could sit under water for days at a time,” she says.

She built this deer fence, then got a friend to help her raise it and install it. That’s the Mianus in the background.

Her heavy reliance on evergreens adds four-season interest, serenity and a lush fullness. “In the winter — guess what? — the garden looks just like this, except for the grass.”

The view from her back porch:

Tourgoers will find a different sort of garden than they may be used to, one that relies heavily on structure, texture, stone and every shade of green you can imagine.

“Minimal use of flowers is the key to my garden,” she says. “People can see that an ‘all green’ garden can be as good as a flower garden.”

In recent years, her garden has been part of the Garden Conservancy’s Open Days Program and she says she’s happy to open it for the Girl Scouts.

“My daughter was a Girl Scout and I was a Girl Scout leader for many years,” Thomsen says. “It’s a cause that’s near and dear to my heart.”

Cheryl at age 3:

If you go

What: “Rhapsody in Bloom,” annual Girl Scouts garden tour

When: 10 a.m. to 4 p.m. Saturday, rain or shine

Where: Nine gardens in northern Westchester

Tickets: $40; $65 ticket includes plated lunch at noon, one seating only, at the Hammond Museum and Japanese Stroll Garden, 28 Deveau Road, North Salem; reservations required.

Information: Contact Ann Marie Imbriale at 914-747-3080, Ext. 239 or aimbriale@girlscoutshh.org or visit girlscoutshh.org.

Also: Two gardens on the tour will be open later this summer as part of the Garden Conservancy’s Open Days Program. Phillis Warden’s Bedford Hills garden will be open on July 19 and Dick Button will open his North Salem garden on Sept. 13. For more information, call 888-842-2442 or visit gardenconservancy.org/opendays.