An H-E-B grocery store that opened near uptown Houston in 2015 features more than just produce. The building’s west side includes a pair of green walls with 24,000 plants—one of the largest in the area.
Designed and installed by McDugald-Steele, a landscape architectural, construction and management firm headquartered in Houston and Austin, the green walls stand 14 feet tall and stretch 250 feet. Irrigation products for the project were supplied by Ewing Irrigation and Landscape Supply, according to Luis Andrade, an account manager for Ewing.
Testing for moisture management
When H-E-B decided to build the new store, William Triplett, the senior vice president of strategic design, chose to include a vertical garden to make the property stand out in an urban landscape.
Daryl McCann, design department manager at McDugald-Steele, helped lead the project. He was concerned about the green walls’ moisture levels—a green wall can dry out quickly, and overwatering can easily create fungus problems—based on his past experience designing more than 24 green walls, and requested assistance from Ewing.
“When Daryl asked me how Ewing can help, I asked him to build a small test green wall at his office, and install a Baseline irrigation controller and soil moisture sensors,” Andrade said.
The firm built two small vertical gardens with a variety of grasses for testing in Houston and at H-E-B’s headquarters in San Antonio, using Baseline’s BaseStation 1000 smart irrigation controller.
Selecting the right plants
The green walls were to be built on the property’s west wall, which would keep them in shade in the mornings, and increase sun exposure in the afternoons—especially in summer. Given the site location and the weather in Houston, not just any plants could do.
“When we started, H-E-B wanted very low maintenance plants,” McCann said. “There is no such thing as ‘no maintenance plants,’ but we can minimize it as much as possible by using hardy plants.”
“So we did a lot of research—we talked to a local horticulturalist and tapped all the experience in our office—to come up with a list of about 50 plants.”
The firm narrowed down the list to 20. The results of the test pilot project at the San Antonio site helped the firm identify and choose six plants known for their hardiness and durability: flax lilies, rosemary, society garlic, Mexican sedum and juniper.
Installing the right irrigation
When construction began, the firm installed a vertical irrigation system with a BaseStation 3200 controller and soil moisture sensors. This allows McCann to remotely control the green wall’s irrigation, and monitor and adjust water usage.
The green wall has three zones, and because it’s vertical, the water from the top zone irrigates the other zones. To keep the plants from drying out too much, the H-E-B green wall is watered for one minute, every half hour, six hours a day.
The irrigation system includes about 3,000 pressure-compensating drip emitters, and a fertigation system with an underground tank and pump that delivers fertilizer through the irrigation, according to Andrade.
“Each zone contains a moisture sensor, so we receive indications when issues like low flow conditions or power failures occur,” McCann said. “I can monitor it from my desk.”
McCann designed the green wall with fabric for its growing medium, so “plants and the soil they’re growing in are stuffed in small pockets in the fabric,” he said.
The plants’ roots then grow out of their soil and into the fabric, and the fabric becomes the growing medium. With a thin layer of soil and an abundance of oxygen, the risk of fungus is reduced, according to McCann.
A monument to careful design and hard work
McCann inspects the irrigation system from his computer at least once a week to ensure optimal performance.
“Caring for a living wall is not a casual thing,” McCann said. “We did it for H-E-B because they really had a passion for it and wanted the project to be successful.”
Today, the 24,000 plants on display for passersby to enjoy are also a monument to careful design and hard work.