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Stack 'Em High: Modular Living Walls
New Orleans Botanical Garden, City Park

CARBO Landscape Architecture, Baton Rouge
by David Olson & Editor, Steve Kelly


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The green wall has an L-shaped design, with the long leg of the L stretching 74', and the shorter leg 31', each with a portal. The larger portal (left) stands 10' by 10'. The smaller portal is 8.5' wide by 10' tall. The green wall extends over the portals, and at its highest point reaches up 12 feet. Plant selection for the wall focused on specimens that could handle heat and humidity, nonblooming plants like Mondo grass, Mexican heather and Silverdust Dusty Miller Maritima. Other selections were Compact Sprenger asparagus fern and Ruellia dwarf white. Ribbons of annuals (yellow lantana, foreground) sweep the groundplane.


The new Arrival Garden and Event Court at the New Orleans Botanical Garden in City Park features a 1,000 sq. ft. green wall. Construction began in May 2016, with products supplied by Ewing Irrigation and Landscape Supply. The green wall debuted September 30.

The green wall was built using the VGM Modular Living Wall System (Tournesol Siteworks). Recycled plastic planting modules attach to stainless steel hanging rails. Each module includes four hanging brackets and growing media, and is 19 inches wide by 22 inches tall.



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The green wall features 5,000 plants in 302 modules, with 16 plants per module. Each module includes four hanging brackets and growing media, and is 19 inches wide by 22 inches tall.


"This garden is only about 13 acres, so we don't have a lot of big floral displays like you see at other gardens. So, we thought instead of horizontal, let's go vertical," said garden director Paul Soniat.

City Park switched the garden's entrance to directly across from the Woldenberg / Goldring Great Lawn on Victory Avenue. The sculptural wall is the starting point for two new main pathways. The wall has a L-shaped design. The long leg of the L is 74', and the shorter leg 31'. Each leg along the walkway has a portal. The larger portal stands 10' x 10'; the smaller portal is 8.5' x 10' tall. The green wall expands over the portals, reaching up to 12' at its highest.



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As the garden was created during the WPA era, circa 1930s, many of the underground utilities were unmarked and required test diggings for the foundations. The green walls are freestanding. The mounting structures are 5" x 5" x 1/4 " galvanized steel posts. The height of the posts ranged from 5' to 17', installed at a 6' depth in the ground to withstand the next hurricane that blows by.


CARBO Landscape Architecture in Baton Rouge, La., designed the wall. "We wanted to provide a feature that made a statement and drew visitors through the Arrival Garden, and that's where idea for the portals and varying wall heights originated," said Zach Broussard, ASLA, a landscape architect and project manager at CARBO. "We wanted most of the wall to be tall enough so people couldn't see over it, but we also wanted visitors to get glimpses of the garden spaces beyond."

"We worked closely with the garden's horticulture staff to determine the most suitable plants for the climate and their maintenance capacity," said Broussard. The wall features 5,000 plants in 302 modules, with 16 plants per module. Plants include Mondo grass, Mexican heather, Silverdust Dusty Miller Maritima, Compact Sprenger asparagus fern and Ruellia dwarf white. "There's also annuals sweeping along the wall down to the ground and wrapping back up onto the wall," Broussard added.



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The modules were assembled with the soil medium inside fabric bags at the nursery, then laid under shade. Selected plants include regular Mondo grass, Silverdust Dusty Miller Maritima, and compact Sprenger asparagus fern. Luis Andrade, a specification manager with Ewing, explained the plants were given five to eight weeks to get established, so as not to shock the roots when they were installed on the structural supports.
Photo: Ewing


CARBO Landscape Architecture in Baton Rouge, La., designed the wall. "We wanted to provide a feature that made a statement and drew visitors through the Arrival Garden, and that's where idea for the portals and varying wall heights originated," said Zach Broussard, ASLA, a landscape architect and project manager at CARBO. "We wanted most of the wall to be tall enough so people couldn't see over it, but we also wanted visitors to get glimpses of the garden spaces beyond."

"We worked closely with the garden's horticulture staff to determine the most suitable plants for the climate and their maintenance capacity," said Broussard. The wall features 5,000 plants in 302 modules, with 16 plants per module. Plants include Mondo grass, Mexican heather, Silverdust Dusty Miller Maritima, Compact Sprenger asparagus fern and Ruellia dwarf white. "There's also annuals sweeping along the wall down to the ground and wrapping back up onto the wall," Broussard added.



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LED fixtures illuminate the green wall and entrance. Photo: Ewing


"With the VGM system, you'll need five to eight weeks to establish the plants, otherwise they go into shock when you install the wall," explained Luis Andrade, a Ewing specification manager. Constructing the wall took two days, with drip emitter spikes going in the modules as the crew built up the wall's columns.

What Healthy Watering Means for a Green Wall
Green walls require a balanced, consistent irrigation, care and attention beyond what a typical lawn requires.

"We consulted with colleagues who had built green walls. Their biggest warning was to make sure the irrigation designed worked correctly," Broussard said. "If you water every module the same amount of time, the water from the top migrates down and the bottom modules get too much water. If you reduce the irrigation time to mitigate that effect, the top modules don't get enough water."

The green wall is irrigated with 3/4 " blank drip tubing in six zones, with 1/4 " distribution tubing hooks onto 265 multi-outlet emitters to deliver water into the top of each module. Laid out end-to-end, the tubing would reach 750 feet. The system also has a rain sensor.



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Adjacent to the New Orleans Botanical Garden is an open area of 200-year-old, Spanish moss-laden live oaks. The park is purported to have more mature live oak trees than any place in the world. City Park has enchanted visitors since 1854. The rectangular shaped park, about half as large as New York City's Central Park, runs from Esplanade Avenue up to Robert E. Lee Boulevard, with Lake Pontchartrain lying nearby just to the north.


Designing to ensure the water goes to the proper place was just as important as designing for the proper volume of water. To keep visitors from getting dripped on as they walk under the portals, custom gutters were attached to the framing to direct overflow to the sides.

Two-sided Green Walls: Twice the Challenge
A typical green wall has an existing structure on which to mount its rails. City Park's green walls are freestanding and two sided. Rotolo installed 5" x 5" x 1/4 " galvanized steel posts ranging from 5' to 17' tall and buried to a six-foot depth, a necessary precaution for an area prone to hurricanes.

Construction required a long lead-time. "With the elevations in New Orleans being below sea level, it doesn't take long during excavation before you reach groundwater. We also got heavy rains in the afternoons, so excavating to six feet was a real challenge," Broussard added.

Once the wall's structural needs were met, the design focused on aesthetics.

"The green wall modules wrap around and over the portals. As you walk through, they cover the two sides of the threshold, and wrap around the back sides, so no matter which direction you're walking, you see a green wall," Broussard explained. "Since the wall is visible from both sides, we clad the back in perforated metal panels to hide the inner structure. And because the wall is not one constant height, we made sure the support posts were in the correct locations and heights so people don't see them where the wall steps down," Broussard added.

The floodwaters are long gone and City Park is reborn.

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Resurrection
In "Resurrection of a Garden" (www.landscapeonline.com/research/article-a.php?number=8689), by editor Stephen Kelly (LSMP April 2007 issue), John Hopper, then director of New Orleans City Park, described the damage to the park after Katrina made landfalls in southeast Louisiana as a category-3 storm on the morning of August 29, 2005. When the levees were broached, 90% percent of the park was under water (one to eight feet deep) for up to three weeks.

Saltwater entered the park and killed or damage most of the grass (including that of the three golf courses) and vegetation in the New Orleans Botanical Garden (NOBG). Pine trees snapped by the dozens; a thousand trees toppled, with hundreds more dead or dying.

Before the hurricane, City Park had 260 employees, but by Aug. 2006 all but 23 employees were laid off. Aided with a $1.1 million grant from the Azby Fund, the Botanical Garden was restored. This early 2006 photo shows horticulturist Melinda Taylor planting annuals in the garden. The NOBG reopened to the public on March 4, 2006, a little over six months after the flooding.



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LED fixtures illuminate the green wall and entrance. Photo: Ewing


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The Sydney and Walda Besthoff Sculpture Garden
The Sydney and Walda Besthoff Sculpture Garden in City Park occupies five acres adjacent to the New Orleans Museum of Art and across from the New Orleans Botanical Garden. A reconfigured lagoon bisects the site, which has a landscape of grass, mature pines, magnolias and live oaks. The Sculpture Garden includes 64 sculptures, most of them donated to by the Sydney and Walda Besthoff Foundation.



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Photos: Editor Steve Kelly


As seen in LASN magazine, January 2017.






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Last Updated 06-19-17