Kit Byrne cuts across Rittenhouse Square's six-acre park every morning as she walks to her job at Children's Hospital of Philadelphia.

For the last few months, she has looked for signs of progress on her way home. "It reminds me of a painting being created," said Byrne, of Fitler Square. "First the canvas is prepared, then the layers start to accumulate, and you can begin to see what the final idea will be."

In this case, the final idea is a landscape rejuvenation, the last phase of a $1.5 million restoration of the park that also included new irrigation, a fence and fountain renovation, new sidewalks, and the repair or replacement of more than 300 stone balusters.

On Monday, the chain-link fence encircling three garden beds flanking the central guardhouse will be removed like wrapping paper on a present, revealing the most extensive horticultural restoration since 1913, when famed architect Paul Philippe Cret transformed a scruffy square of dying trees and broken shrubbery - replete with a trash pit in one corner - into a beaux arts masterpiece.

The project didn't start as such, as Friends of Rittenhouse Square president Betsy Hummel described it. "The original impetus was to address overdue maintenance. We wanted to improve the lighting in the square, to restore the main fountain, and to conserve, and where necessary, replace, the stone balusters," she recalled.

But Hummel always knew that once the structural repairs were completed, the Friends would want to turn their attention, and by necessity, their prodigious fund-raising ability, to the landscape.

"There was nothing wrong with it; it was just tired," she said. "The beds were edged with grass that wouldn't grow; the plantings were over-mature and no longer thriving. It looked nice in the spring, but the rest of the year, it was pretty deplorable," especially in contrast to the recent improvements within the park.

So the Friends raised an additional $250,000 from residents and local businesses to finance a horticultural redo and yearlong maintenance contract.

Working with the Department of Parks and Recreation in late 2014, the Friends contracted with TEND, a landscape architecture firm with a focus on the relationship between design and maintenance, to come up with a plan. Staying loyal to Cret's original formal axial design, incorporating paths running diagonally and crossing at a central feature, the firm found inspiration in the watercolors of French artist Sonia Delaunay and also riffed on the square's namesake, David Rittenhouse, an astronomer who built the first U.S. telescope.

Although less pronounced than in earlier iterations, the final design uses vertical elements (representing stars) - "Dee Runk" boxwood and "Dragon Lady" hollies as punctuations - connected by diagonal lines of low shrubbery to mimic the outline of a constellation. Within a few years, the individual plants will grow together, forming a continuous trimmed hedge.

The park's heavy traffic - children on scooters, office workers on lunch breaks, political organizers, the homeless, and teenagers from across the city - would seem to demand a design and plantings selected foremost for indestructibility.

But from its conception, TEND envisioned the project as an ornamental garden, as opposed to an institutional landscape, with plantings of vines, perennials, flowering shrubs, spring bulbs, and even a rose garden, all maintained using organic methods.

Soil tests showed the fertility level was already quite high, so they brought in Mark Highland of Organic Mechanics.

After clearing the beds of the old plantings, broken irrigation pipes, tent stakes, and a recently interred cat roused from eternal rest, he recommended tilling in large amounts of biochar - pure carbon processed to act like a reservoir, holding water and nutrients for plants in times of drought or stress.

The project wasn't without challenges, and the first arose because of an industry-wide shortage of boxwood (the structural backbone of classical horticulture), the result of a devastating blight.

The shortage was exacerbated by Longwood Gardens' reserving 3,000 of the plants for its $90 million fountain project, now halfway complete.

Liz Haegele, owner of Fine Garden Creations, the firm installing and maintaining the Rittenhouse project, contacted growers across the East Coast before finally tracking down the necessary 250 plants outside Chicago and transporting them to Philadelphia via tractor-trailer.

But immediately after they were installed, a water main broke during a nearby sidewalk replacement, leaving her unable to irrigate the shallow-rooted (and irreplaceable) new plantings.

"It was very stressful," Haegele said. Several days later, the city was able to open a valve under the fountain that allowed her crew to hand-water the boxwood in the meantime.

With the completion of the new landscape, restoration work at Rittenhouse will conclude for now. "As far as big projects, we've touched on everything that needs to be done beyond ongoing maintenance," Hummel said with relief.

Philadelphia Parks and Recreation Commissioner Kathryn Ott Lovell said she couldn't be happier with the design.

"It's horticulturally complex without being fussy; it's modern, but it resonates with the historical character of the park."