For the newly-planted irises at Flat Branch Creek, late spring rains that soaked Columbia have been just what the horticulturist ordered. The runoff has been nourishing the young buds with their first taste of the silt and nutrients that they will thrive on in the coming summer.
The irises were planted for their ability to stabilize the creek bank and their role in filtering runoff, slowing the speed of flash flooding and reducing erosion.
City horticulturist Daniel Gibbons is eager to win the battle against invasive species that have infiltrated the banks in Flat Branch Park.
“Our goal is to get into the creek before the invasive species get in,” Gibbons said. “If we don’t get in here with native plants, then we will be facing a battle with the eradication of honeysuckle and Japanese knotweed.”
Gibbons was leading a group of Columbia Aquaculture Restoration Program volunteers. The city began the program in March, educating volunteers about storm water runoff, aquatic plants, insects and rain gardens. In return, the volunteers donate their time on aquatic restoration projects in city parks that go beyond routine maintenance.
Helping native species, such as the iris, become established in Flat Branch Creek is an initial step toward rehabilitating the creek ecosystem, which will include the planting of blue star and river oats, in addition to trees and shrubs.
On their first outing beyond the classroom, volunteers were put to work filling burlap bags with soil topped by an iris rhizome. Their counterparts, ankle-deep in the water, dug into the rocky bottom forming cradles in outcroppings, where they anchored the bags with stones to prevent them from being washed away.
“I feel like I’m stealing from Peter to pay Paul,” volunteer Cheryl Hardy said as she searched for nearby rocks to anchor an iris. “I bike this way to work every morning, and I like the idea of seeing the fruits of our labor. It makes you appreciate the backhoe.”
The CARP volunteers were joined by stormwater outreach educator Mona Menezes and city volunteer coordinator Leigh Nutter, who brought coffee and donuts to perk everyone up for the 8 a.m. start time.
“Irises are a great example of native plants that require fewer inputs,” Menezes said. “They thrive on neglect after getting established, requiring little to no maintenance. During the first one to two years, they grow root systems that break up the clay and aerate organic matter for soil, improving its overall quality.”
Irises can also thrive in rain gardens, which are low-lying areas where excess rainwater collects. Rain garden plants soak up the water and return the moisture to the air through transpiration.
“Part of the runoff management at Flat Branch includes a rain garden, which will catch contaminants from the parking lot and prevent them from entering the creek,” Menezes said. “The pollutants will be taken up by the plants and contained in the rain garden, instead of flowing downstream into more fragile ecosystems.”
Volunteers teamed up in bagging and planting crews had sown all but 70 irises after 2½ hours of work.
Rhea Rostine, a groundskeeper with the Parks Department, was appreciative of the volunteer efforts.
“They save us a couple of days of work,” Rostine said. “This would take us about 16 hours with a crew half the size of what we have out here today.”