About Mercer

In the late 1940s, Thelma and Charles Mercer purchased a beautiful 14.5 acre tract of natural land along Cypress Creek. Thelma was an avid horticulturist, and she and Charles did much of the initial selective clearing to make space for some of her favorite native trees that included dogwoods, rusty black-haw viburnum, several species of hawthorns, plus many others. Thelma also planted large camellias that are still seen throughout the central gardens. She also introduced many other plant species, such as camphor, Ginkgo, BauhiniaPhiladelphus and tung oil that naturalized and are still growing beautifully.

When it came time for the Mercers to retire, they could not bear the thought of a developer bulldozing their “paradise.” So, in 1974, they convinced Harris County to purchase their original 14.5 acre tract with the stipulation that it would grow and be maintained as an educational and horticultural facility for the public’s enjoyment.

After Harris County purchased the land, a group of community gardeners interested in furthering the development of Mercer as a botanical facility formed the nonprofit group Mercer Arboretum Advisory Committee (MAAC). In 2000, the organization changed its name to The Mercer Society and members assist Mercer Botanic Gardens in its mission by organizing and implementing activities that encourage membership support, expand community awareness, and raise funds in support of Mercer’s strategic plan.

Since 1984, through donations and land purchases made by Precinct 4, Mercer has grown to more than 400 acres.

The arboretum and botanic gardens are divided by Aldine Westfield Road. On the east side is the botanic gardens where over 60 acres of beautifully maintained gardens feature bamboo, color displays, daylilies, endangered species, ferns, gingers, herbs, tropicals, to name a few. The east side also has an extensive walking trail system, a Remembrance Walk for memorials and honorariums, ponds, a visitors’ center, courtyard plaza, plus much more.

The arboretum on the west side of Aldine Westfield features two playgrounds, a picnic area nestled in a woodland setting with two barbecue pavilions, plenty of picnic tables, a hickory bog and boardwalk, cypress swamp, maple collection and several miles of walking trails that wind through beautifully preserved woodlands.

Mercer employs a team of experienced botanists, horticulturists, and gardeners who offer a wealth of knowledge and information, and will gladly assist you in anyway they can during your visit.

In Memory of Thelma Mercer

“The idea of bulldozers coming in here and destroying the work of nature that we had tried to preserve and learn about and learn to love and enjoy is hard to take.”

—Thelma Mercer (left) in a letter to Harris County in 1973

“Thelma Loraine Mercer, a visionary and horticultural leader, passed away peacefully in her home in Zapata, Texas, September 20, 2000. She would have been 98 years old December 21, 2000.”

—Excerpt from obituary

Mercer Arboretum & Botanic Gardens owes its existence to Thelma and Charles Mercer, who bought 14.5 acres of wild woods alongside Cypress Creek in 1949. The only opening in the wooded land was a small burned area. Over the next 24 years, the Mercers created a garden paradise despite floods, droughts, and nature’s other familiar ravages.

Additional land was cleared to make space for existing native trees such as dogwoods, parsley hawthorns, and rusty blackhaw viburnums.

Other trees and shrubs including camellias, gingkos, orchid trees, and azaleas were planted by Thelma and Charles. Many of these original trees and plantings are thriving today in the central gardens of Mercer.

Initially, Thelma Mercer was someone who, in her own words, “didn’t know one plant from another.” But she became an accomplished horticulturist and spent much of her time digging flowerbeds, planting, and potting plants. The goldfish pool near the staff building was dug by Charles Mercer as a focal point in the gardens.

In 1973, Charles retired and the Mercers decided to move to Zapata in the Rio Grande Valley. It must have been a difficult decision to leave a place in which they had invested so much labor and love. Rather than sell their beloved paradise at a profit to developers, Thelma wrote to county officials recommending that the county purchase the site. Her original letter is at Mercer today. Although the Mercers were not wealthy, they offered the property to Harris County at a price far below its market value, with a stipulation that it would be used as a garden and horticultural education facility. With the lobbying efforts of many garden clubs and community leaders, Harris County bought the property.

Thelma and Charles Mercer’s vision became reality: Mercer Arboretum & Botanic Gardens, a nationally recognized, 300-acre horticultural treasure, now showcases the Gulf Coast Region’s largest collection of native and cultivated plants. Each year 250,000 visitors, including thousands of children, come to Mercer to enjoy the gardens and learn how important plants are to the environment and the community’s quality of life.

—Originally published in the winter 2000 issue of theParkscape

In Memory of Charles Mercer

“There is not much he can’t do.”

—Thelma Mercer talking about her husband, Charles (left), in an 1996 interview.

In 1949, Thelma and Charles Mercer bought 14.5 acres of East Texas piney woods alongside Cypress Creek. Together they cleared the land and created a beautiful garden oasis. Upon Charles’ retirement in 1973, the Mercer’s generously offered their property to Harris County at a bargain price. Harris County bought their property and established Mercer Arboretum & Botanic Gardens, a nationally recognized Harris County Precinct 4 Park.

Lt. Colonel (Ret.) Charles L. Mercer passed away peacefully at the age of 91 in his home in Zapata, Texas, on July 22, 2001, less than a year after the death of Thelma. They were married 59 years. While much has been written about Thelma Mercer, little is known about Charles, the co-creator of a place that has brought pleasure to so many people.

Decorated soldier, recognized engineer, dedicated civic worker–Charles Mercer was born in 1910 in Oklahoma. He served as a communication engineer in the U.S. Army in the South Pacific during World War II. He was decorated three times and retired after 30 years as a Lieutenant Colonel. As a Bell Telephone engineer, he worked with the military to construct an early warning system inside the Artic Circle, an effort that earned him a commendation from the military in 1957. He attended Rice University, the University of Houston, and Tulsa University, and was awarded an honorary doctorate from the University of New Mexico. After retirement to Zapata, Charles and Thelma became very involved in civic affairs, especially in support of the local library and education. Several students received funds from the Mercers for college expenses.

The property that the Mercers came to in 1949 was, in Thelma’s words, “a wild, wooded, burned-out area.” The Mercers built their first home (today’s Volunteer Cottage) and began to selectively clear the land to make more room for trees such as dogwoods, rusty blackhaw viburnums, and hawthorns. Thelma planted large camellias that bloom throughout the central gardens, and introduced several exotic tree species that are still growing beautifully, including gingko and bauhinia. They fought the elements, including a flood before the roof was on the cottage, and millions of mosquitoes.

Charles’ abilities as an engineer and handyman were utilized on many projects. One of the favorite places at Mercer for photographers and children is “Thelma’s Pond,” a small pond with Koi and large goldfish. Years ago Thelma commented she would like to have a pond. Charles had her lay out the desired shape of the pond with a garden hose and he dug and constructed it. He did the concrete work and Thelma laid the bricks along the edge.

Today, Thelma’s personal desk, where she wrote her letter offering the property to Harris County, resides in the Visitor’s Center and her “spirit” as garden advisor lives on at Mercer. Much has changed at Mercer since Charles and Thelma labored together to clear trees and plant their garden. The one thing that has not changed is their dream for Mercer to be a place that is educational and enjoyable to others. Each year 250,000 visitors enjoy Mercer’s gardens and learn why plants are important to our environment and quality of life.

Originally published in the spring 2002 issue ofParkscape

Events & Programming

Mercer Botanic Gardens offers a variety of innovative, educational, and entertaining programs. These programs include a cornucopia of horticultural-related topics covering local native and invasive plants, butterflies, botany, wild edibles, tree walks, and birding tours.

An annual event in October, featuring a plant sale, scarecrow building contest, festival activities and more.

Summer Garden Club is a series of workshops hosted at Mercer Botanic Gardens on select Saturdays.

March Mart, Mercer’s largest plant sale, is held each March and highlights unusual and choice plant varieties unavailable in local markets.

Held the Spring and will include festival activities including face painting, crafts, and more.

Celebrate the holiday season with music, food, crafts, shopping, and more during Holiday in the Gardens.

Mercer Botanic Gardens offers many events and activities including, fishing, pontoon boat tours, stargazing, tree planting, and more.

All programs are open to the public. The program schedule is published seasonally. Due to space limitations, some programs require reservations or are open to one reservation per person/household. Group reservations are not allowed unless otherwise indicated. All private and school tours require preregistration. Anyone requiring special assistance to participate in any program should contact the park beforehand. Comfortable, closed-toe shoes and the use of insect repellent are recommended year-round.