Flood-damaged gardens still digging out
It will take years, funds for Mercer to regain beauty
Nature doesn’t respect gardens any more than homes and roads when it rains fury.
During the Tax Day floods that claimed nine peoples’ lives and damaged more than 6,700 Houstonarea residences last month, parks along the overflowing bayous suffered, too. The raging water scraped banks clean in some areas, then piled them higher in others, evidence of the ageold dance between erosion and silt.
Mercer Botanic Gardens, a horticultural treasure that hugs Cypress Creek in northwest Harris County, was especially hard hit. Although the visitors center and front half of the 20-acre botanic gardens reopen to the public on Wednesday, director Darrin Duling said it will
take years for the landscape to return to its former glory.
For three days, as much as 7 feet of rushing floodwaters inundated the county-owned park, which holds the region’s largest collection of native and cultivated plants. The flood swept through Mercer’s original cottage, carried away blooming annuals, stripped bark from trees, fried the public address system and damaged electrical and irrigation systems.
Sections of the high creek bank collapsed, crumpling large trees and overlook trails in a justcompleted area called the Creekside Ramble. When the water finally subsided, a landscape of sandy silt with dunes as deep as five feet was left behind.
The Creekside Ramble looks oddly beached. For weeks now, park staffers have been shoving the khaki-colored silt around with backhoes that look like toys in a desert. Identification tags poke up from the sand next to young plants that have shriveled and died. Instead of the scent of honeysuckle and magnolia, the putrid smell of decaying plant material lingers.
Duling said he doesn’t know how many of Mercer’s more than 10,000 species of plants will still be alive by the end of this year.
“Root rot takes a while to set in,” he said.
Nor did he want to guess how much it will cost to restore the park. Mercer covers 300 acres total and includes a heavily wooded area on the west side of Aldine-Westfield Road, where picnic grounds have reopened but primitive trails that washed away in the flood remain closed. Duling is still assessing the damage. The county has applied for FEMA funding, and insurance may cover some of the repairs.
It’s a devastating setback for the 42-year-old park, which gets about 250,000 visitors a year. Although Mercer has an annual operating budget of about $1.5 million and a staff of 33, it depends on an army of volunteers that is only now evolving into a major fundraising organization.
Volunteer coordinator Suzzanne Chapman, a Mercer staffer for more than 20 years, said April’s flooding was the worst she’s seen — worse than Tropical Storm Allison in 2001 and Hurricane Ike in 2008, when a tornado felled trees.
Showplace for flowers, trees
The Creekside Ramble was supposed to be a showplace for camellias and more than 100 varieties of small, graceful Japanese maples. Donated to Mercer by a specialty nursery, the maples had been carefully tended and brought to maturity by staffers during more than a decade.
Even if money were no object, Duling said, “You can’t just go buy trees that size.”
The ramble, which replaced a forest decimated by the 2011 drought, also featured winding trails that allowed visitors to peer across the steep banks of Cypress Creek. Mercer’s Japanese tea house also took in a deep carpet of silt. It overlooks Storey Lake, which likely will have to be pumped out.
The erosion-silt dance is happening at other parks, too.
During last year’s Memorial Day flood, water rushing through Buffalo Bayou, Houston’s central waterway, shaved off a large hill at Memorial Park’s Hogg Bird Sanctuary. Much of that soil likely landed in Buffalo Bayou Park just downstream, which gained a beach of silt near Shepherd Drive that buried newly-planted vegetation.
The April 18 floods brought another load of silt.
Buffalo Bayou Partnership president Anne Olsen said new plants in the area haven’t had time to get established before they’re washed away or smothered. April’s floods also brought more significant erosion than Olsen has seen before, washing out ground from several stretches of trails and sending trees into the bayou east of downtown.
And Buffalo Bayou is still high. As much as 3,500 cubic feet a day of retained floodwater is still being released from the Addicks and Barker reservoirs — nearly twice the normal amount. That flow has kept Buffalo Bayou rushing for more than a month.
For millennia, the land has reinvented itself during floods, bringing new, fertile soil to low areas. Problems occur when humans try to harness bayous and build things in the floodplain, said John Jacob, director of the Texas Coastal Watershed Program. “In Houston, we have a problem recognizing that rivers are active.”
Like much of the development around it, Mercer sits in the 100year flood plain.
While the county has expanded the park significantly since 1984 and kept the western twothirds natural, the botanic garden wasn’t designed as a flood retention zone like so many of the region’s newer parks.
Seeing gardens’ potential
Mercer was established in 1974, after Humble residents Thelma and Charles Mercer persuaded Harris County to buy their home and the 14.5-acre garden they had tended since the late 1940s. It has always focused on plant collections and research. Thousands of home gardeners attend Mercer Society’s lectures and plant sales to learn about varieties that will flourish in the Gulf Coast region.
Duling’s predecessor, Linda Gay, helped introduce more than a dozen species of easy-to-grow plants to the Houston-area market — especially gingers, bamboos and Japanese maples — during her 25-year tenure.
Duling, who calls himself “a full-fledged plant geek,” arrived in 2011 after nine years as curator of the glass house collection at the New York Botanical Garden.
He wants to make Mercer’s collections “more scientifically significant” by harnessing the gardens’ potential as a conservatory for endangered tropical and subtropical plants from around the globe.
That’s one reason the nonprofit Mercer Society, whose volunteers raise the seedlings and cuttings from the gardens’ collections for plant sales, recently rebranded. Society president Maryanne Esser said her group now aims to raise major funds like the conservancies that have pumped millions of dollars into Hermann, Buffalo Bayou and Memorial parks.
‘It has become a need’
The society wants to acquire more than 30 adjacent acres above the flood plain, starting this year with two tracts totaling 10 acres that will cost more than $800,000.
“It’s not a desire any more. It has become a need, and we have a limited window of opportunity,” Esser said. “We have to make sure the gardens are protected.”
In the meantime, the cleanup is a mind-blowing task, Duling said. “People don’t think about all the residual things — like replacing all the valve boxes on the irrigation system because all the lids blew off.”
Many plants will be cut back or left alone until it’s clear whether they will return. Crews have made great strides, Duling said, and friends from other botanic gardens and the commercial nursery world have offered to help replant collections.
“Our living collections promise to be better than before as a result,” he said.
Still, he misses the dying Wollemi Pine, a rare tree in the prehistoric plant beds. The species was known only from fossils until it was rediscovered 20 years ago in Australia.
“We had one more than seven feet tall,” Duling said, “and it was growing beautifully.”
With or without human intervention, nature still takes her time.