Rain gardens reduce storm water runoff in urban areas.
By Alison Graef
Landscape and gardening experts and community members installed a rain garden in front of Sinkin Eco Centro during a workshop hosted by the San Antonio River Authority and the center April 29.
Academic program specialist Jess Mayes used a tractor scoop to pre-dig a one-foot deep, 20-by-10-foot wide hole in front of Eco Centro by the sidewalk on East Locust Street.
The lowered garden will slow down and partially absorb overflow from the center’s 27,000-gallon rain catchment cistern.
This is meant to lessen the amount of water that flows from the property into the streets and storm drains during heavy rains.
“Today I would hope that people would learn a little more about rain gardens and how they mitigate flooding, a little bit more about the technical aspect of it — depth, sizing, things like that. These are the questions we get a lot,” Mayes said.
Volunteers leveled the hole and removed large rocks and then dug out smaller holes with shovels and a pickaxe to plant the one-gallon plants.
Each plant was thoroughly watered after it was planted and, finally, was surrounded with a layer of mulch.
Emily Hawthorn, local resident and certified Texas Master Naturalist, came to the workshop to learn how to install a rain garden on her own property.
“The most useful thing was actually putting plants in the ground and being told the right way to do it,” Hawthorn said. “I’ve done it all my life but not necessarily the right way. … This was a really good chance to not only learn the science behind it but actually put my hands in the dirt.”
Lee Marlowe, sustainable landscape ecologist at San Antonio River Authority, helped lead the workshop.
“It’s going to serve as a nice demonstration garden that people can go and see,” Marlowe said.
Eco Centro Coordinator Julie Cornelius said five plant species were chosen for the garden — Gregg’s Mistflower, Lindheimer’s Muhly, Frogfruit, Wooly Stemodia and Mealy Blue Sage.
The plants are all native and do well in full sun, Marlowe said.
Marlowe said two of the plants are also Monarch nectar plants, so they will attract and cater to the Monarch population.
Rain gardens are meant to hold back storm water during heavy rains in urban areas, Marlowe said.
Because of the vast amount of impervious paved areas in cities, storm runoff does not have a chance to be naturally absorbed into the ground and flows quickly, increasing the chance for localized flooding.
Additionally the water picks up pollutants and carries them into storm drains and, ultimately, into the river.
“Rain gardens generally don’t hold water for long periods of time,” Marlowe said. “They are only meant to slow the water down and just hold it back a little bit instead of sending it directly into the storm drain.”
Rain gardens not only hold back water, they also allow for some of the water to be absorbed naturally into the ground.
The soil, mulch and plants serve as a natural filter for pollutants as it is being absorbed or flowing through.
“It mimics the natural process of cleaning the storm water,” Marlowe said. “And so you prevent all of that pollution from going into the river. Even if the water does make it to the river, it’s making it through the ground where it has already been filtered.”
Jake Aalfs, landscape architect from the San Antonio River Authority, said residents are encouraged to install rain gardens on their properties as a part of the group effort to naturally slow and absorb storm water.
“What we have is plants in the bottom that are going to be inundated with water, so those plants have to be able to withstand ‘wet feet,’” Aalfs said. “And then we have plants on the sides and on the top that are going to have less water to them.”
Information on how to install a residential rain garden and what plants to use can be found at www.sara-tx.org/lid-sustainability/how-to-build-a-rain-garden.
To learn more about upcoming events at Sinkin Eco Centro, visit the center’s Facebook page at facebook.com/ecocentro1 or email Mayes at firstname.lastname@example.org.