Marilynn K. Yee/The New York Times

While interning two years ago at Brooklyn Botanic Garden, Karen Orlando would often gaze longingly from the roof of her apartment building in Prospect Heights to a lot below on Sterling Place.

The three-quarter-acre site where a parking garage had once stood had degenerated into an empty, dirt-filled tract.

“It was starting to fill up with garbage,” Ms. Orlando recalled, although in her mind’s eye she could envision it transformed into an urban meadow awash in radiant native blooms and fragrant perennials.

Ms. Orlando had recently read a book called “The 50 Mile Bouquet: Seasonal, Local and Sustainable Flowers,” which compares the movement to encourage consumers to buy locally produced food with another emerging trend to buy locally grown flowers.

She also became inspired by a database, 596 Acres, which provides a map of vacant lots in Brooklyn and encourages people to organize and turn the lots into community gardens, composting sites and parks.

So after her internship ended, Ms. Orlando teamed up with another former Brooklyn Botanic Garden intern, Susan Steinbrock, who designs gardens, to establish Brooklyn Grown, a flower retail business.

But instead of taking on the prodigious and expensive challenge of establishing a large flower farm, they decided to plant wherever they could — in vacant lots, in backyards and just about anywhere they could find unused soil.

“We planted lots of seeds last year in people’s backyards,” said Ms. Steinbrock, who on a recent Wednesday was pushing hundreds of plugs of prairie plants, including yarrow and butterfly weed, into the earth behind Blue Sky Bakery in Park Slope.

“Wow, this is rich stuff here,” she added, talking about the thick layer of black compost blanketing the strip of land, which was made from the bakery’s leftover coffee grounds, banana and carrot peels, and similar discarded food items.

“I think it’s fantastic that she’s turning these spaces that are underutilized into green spaces,” said Erik Goetze, the owner of the bakery.

The two women say that most people they approach do not mind if they plant flowers in unused parts of their backyards.

The lot on Sterling Place, Ms. Orlando and Ms. Steinbrock learned, was a stalled construction site whose owner was in prison for mortgage fraud.

They assumed that he would not be building on the lot anytime soon, so they decided to incorporate it into their flower-growing plan without asking permission. “I figured we would go in and use the space temporarily,” Ms. Orlando said.

Last fall, they planted about 800 tulip and daffodil bulbs on the lot. “It was hard to dig in there,” Ms. Orlando said. “We chose bulbs because we thought they’d do well in rocky terrain.”

They also sowed organic fertilizer into the nutrient-deprived earth. “When I would call it soil,” Ms. Steinbrock said, her partner “would correct me: ‘This isn’t soil; this is dirt.’”

In the spring they moved in some drought-resistant plants, like lilies and forget-me-nots, and transplanted hundreds of anemones (flowers from the buttercup family) from Ms. Orlando’s community garden plot at Floyd Bennett Field. In February, as a result of the unseasonably warm weather, daffodils and grape hyacinths were already sprouting from the ground.

The women turned the flowers they were growing into bouquets and began selling them to friends and establishments like Coffee Bites in Prospect Heights. They also began forming a business plan to forge a relationship with a community agriculture group, which delivers locally grown food to subscribers, to include flowers in its offerings.

By April, they were excited to see the Sterling Place lot ablaze with wild Turkish tulips and sweet bell-like flowers called fritillaria. But more recently, when Ms. Orlando arrived to water the flowers, she was chagrined to encounter a “Keep Out” sign and a heavy lock on a fence surrounding the lot.

“We knew it would be a risk,” said Ms. Steinbrock, peering wistfully through the glinting chain-link fence at some pink, blooming sea thrift she had sowed but would never reap.

While it won’t stop them from forging ahead with Brooklyn Grown, Ms. Orlando did lament the plight of her carefully cultivated flowers.

“It will kill me to watch the mugwort and garbage swallow up the plants we have in there,” she wrote on her Web site, flippetyfloppety.blogspot.com, “but that just may be the reality we are headed for.”