For just one day, the public has the opportunity to stroll two gated waterfront properties owned by the rich and famous in the Florida Keys to see spectacular landscapes.

The Upper Keys Garden Walk on Feb. 24 features the home of filmmaker Jon Landau of Avatar and Titanic fame. His five-acre, oceanfront estate along Millionaire’s Row in Islamorada is as lush as the scenery in the blockbuster Avatar. The rectangle-shaped property is filled with about 500 plant and tree species from 50 countries, including silver palms from Madagascar and zombie palms from Haiti.

On March 3, the Marathon Garden Club House & Garden Tour will showcase an isolated, 12-acre property on Long Point Key called Sunset Point. It boasts one of the largest single-family homea in the Keys — 13,000 square feet.

The new owners of the property at mile marker 56 off U.S. 1 — purchased from the Stanley Switlik family, who made their fortune in parachutes — wish to remain anonymous. But they are allowing people to walk around the deck of their infinity pool with swim-up bar and meander along the spacious grounds that are surrounded on three sides by the Gulf of Mexico and include a tidal saltwater pond filled with tarpon, snapper and barracudas.

The common denominator — D’Asign Source.

Both luxurious landscapes were designed, built and planted by the Marathon-based and family-owned company, founded 50 years ago as Ornamental Cement Products by the late Italian-born Palmerino D’Ascanio.

His three sons — Tony, Franco and Amedeo — now run the business, and over the decades they’ve learned a lot about what works and doesn’t work in the Florida Keys. It’s the only place in the continental United States that has a Zone 11 rating for plant hardiness by the U.S. Department of Agriculture. In Zone 11, temperatures rarely fall below 40 degrees F.

“We can grow a vast majority of tropical plants that you can’t grow anywhere else in the continental U.S.,” said Franco D’Ascanio, president of D’Asign Source. “For instance, I have a few plants in our yard that won’t survive in Homestead.”

But temperature is only one part of the equation. Vegetation in the Keys, depending upon where on a property it is placed, may also need to survive extreme sun, high winds and salt. Occasional hurricane-strength storms also are a consideration.

“In the beginning, we used the dozen plants that most everybody else did here,” said D’Ascanio, whose company mostly subcontracted landscaping until the 1980s. “But once we started taking an interest in it, we started learning about the finer things and quality plants. And most importantly, we learned a lot about growing the right plants in the right place.”

The company founded Palmerino Palms, a nursery for growing rare and exotic palms, in 1996 after the death of the family patriarch. Today, the nursery is called D’Asign Source Botanicals and covers 20 acres in Loxahatchee.

Franco D’Ascanio’s own home on Key Colony Beach also has become a testing ground for different species.

“We grow about 1,000 species, but the database on species we have grown and tried is about 10,000 — it’s not just information we have gleaned from books,” he said.