|By Suzanne Labry
Houston’s magnificent 445-acre Hermann Park celebrated its 100th birthday in 2014. Back in 1914, when real estate investor and industrialist George H. Hermann announced that he was deeding property to the City of Houston for a municipal park across the street from what is now Rice University, one wonders whether he could have envisioned that his gift of green space would be visited annually by six million people a century later. Although the park has seen its share of ups and downs during its first 100 years, its future perhaps has never been brighter than it is today. Its recent success is due in no small part to Hermann Park Conservancy, a nonprofit citizens’ organization founded in 1992 and dedicated to the stewardship and improvement of Hermann Park.
Since then, the Conservancy has raised more than $120 million from foundations, corporations and individuals for improvement projects in Hermann Park. Through a public-private partnership with the Houston Parks and Recreation Department, the Conservancy manages the design of projects and then shares construction costs with the City. The Conservancy also oversees programs focused on volunteerism, visitor services, conservation and stewardship, and tree care for the entire park. One of the group’s most intensive responsibilities is the operation and maintenance of the new 17-acre McGovern Centennial Gardens, a major renovation project in the heart of Hermann Park that took place between March 2013 and December 2014.
In order for the McGovern Centennial Gardens to open as the centerpiece of Hermann Park’s 100th birthday celebration, several substantial feats of engineering had to be achieved in a remarkably short timeframe. To create an uninterrupted expanse for the new gardens, the former Houston Garden Center, which had been a fixture of Hermann Park since 1946, was taken down and its 300-space parking lot was removed. A man-made conical “mountain” called the Garden Mount was constructed to rise 30-feet up on a flat plain to serve as the main focal point of the garden design. Girded by landscaped spiral pathways to the top, the Mount rewards climbers with a panoramic view. In addition to installing water features, walking paths (both gravel and paved) and fencing, nearly 500 trees (more than 50 species), 760 hedge shrubs, 350 roses, 115 camellias, 650 azaleas, 55,000 perennial bulbs, 20,000 ornamental grasses, 4.5 acres of grass and 106,875 other shrubs and perennials were planted. That was a lot to accomplish in less than two years!
The main entry into the Gardens is through the Cherie Flores Garden Pavilion (designed by Bohlin Cywinski Jackson, architects of Apple stores worldwide), which opens onto the Centennial Green, a 350-yard “great” lawn that leads to the Mount. Surrounding the Green and the Mount are themed garden “rooms”: the Perennial Gardens, which flank either side of the Green; the Arid Garden, featuring water-wise succulents and native grasses; the formal Rose Garden, containing numerous varieties of Earth-Kind and antique roses; the Woodland Garden, a shady microclimate spotlighting azaleas, camellias, ferns and bulbs; the Tudor Family Pine Hill Walk, representing the piney woods of East Texas; the Celebration Garden, an outdoor-event venue featuring an open lawn enclosed by tall hedges; and the interactive Family Garden with an edible landscape of seasonal vegetables, herbs, berries and fruit trees. According to Hermann Park’s Director of Horticulture Jane Curtis, “Our idea is to fill the gardens with color all year long — something will always be in bloom.”
Making sure that so many different types of newly planted vegetation are all thriving and looking their best in such a variety of microclimates is the enormous job of Daniel Millikin, lead horticulturist. The sheer scale of the project is daunting enough, but Millikin’s task has been further complicated by the fact that the McGovern Centennial Gardens were created from scratch. Because the multi-elevation Gardens were constructed on the site where a structure and a parking lot had existed for decades, it was necessary to truck in 9,342 cubic yards of new soil in 374 semi-truckloads. Nine different soil mixes were engineered to meet textural and content specifications for the various areas of the Gardens, but the soils were alkaline and biologically non-functional. According to Jane Curtis, “The cost to apply high-quality compost over all 17 acres would have been too high and too labor intensive. We needed some way to improve the soil biology while staying within budget.”
To the rescue came Mother Nature, in the form of rainwater, which the staff is using to brew large quantities of actively aerated compost tea (AACT). ACCT is a water-based, oxygen-rich extract taken from source compost that is brewed for at least 24 hours in aerobic conditions designed to multiply beneficial organisms. The resulting liquid is a culture containing large populations of aerobic microbial biomass. Microbial biomass refers to the living bacteria, fungi, protozoa, nematodes and microarthropods that decompose plant and animal residues in soil. This decomposition makes carbon dioxide and vital nutrients (which would otherwise be “locked” in the soil) available to plants for growth and health. In addition, more biomass increases the amount of water that infiltrates into the soil, reduces soil erosion and increases the amount and variety of life both in and on the soil, including disease-suppression organisms.
At the McGovern Centennial Gardens, rainwater-based ACCT is administered in regular applications, both as soil drenches and as foliar sprays. While it is important to note that any type of compost tea (aerated or not) is intended to complement and enhance, not replace, basic composting and mulching techniques, the result of adding the tea as a major component to improve the engineered soils has been swift and impressive, not to mention cost-effective. Since the tea applications began, soil tests show pH levels balancing out near 7.0 and increases in microbial biomass anywhere from 160 percent to 490 percent. The results are also evident in the overall health of the Gardens’ vegetation. For example, the rooting depth of turf grass in the Centennial Green increased from three-inches to more than six-inches in a single year.
Two rainwater collection tanks were installed for use in the McGovern Centennial Gardens: a 1,500-gallon tank in the Family Garden and a 2,500-gallon tank in the Park’s service yard. A large shade structure with picnic tables underneath in the Family Garden serves as the catchment area for the smaller tank and the roof of the barn in the service lot feeds the larger tank. Rainwater is a crucial element in making the tea because it does not contain any choloramines, the disinfectant commonly added to municipal water systems. Choloramines are designed to kill bacteria, good or bad; they defeat the purpose of compost tea by killing the microbial life it is intended to encourage. And, of course, rainwater is free. An industrial-sized air pump or “brewer” pumps oxygen into the rainwater and compost mix and produces 250 gallons of AACT in a 24-hour period. “From November 2015 to November 2016, our first year of using aerated activated compost tea, we brewed 22,000 gallons,” said Millikin. “We completed five full cycles of applications, with brews designed to increase bacterial load in hotter months and fungal content in cooler months.”
While producing such large quantities would far exceed the capability of the home gardener, that doesn’t mean your landscape can’t benefit from regular applications of compost tea. As long as you have dechlorinated water (rainwater is always best) and good-quality compost, you can make tea, but you should first decide what kind of tea you want to make. There is a difference between actively aerated compost tea (AACT), the kind used at the McGovern Centennial Gardens, and non-aerated compost tea (NCT), the low-tech version. Although the equipment required to make AACT can be readily scaled down for home gardening use (an aquarium pump can do the job) and is not necessarily difficult or cost-prohibitive, it does require set up, monitoring and maintenance. The following points might help you decide which type works best for you:
- Both AACT and NCT are made via a brewing or fermentation process that involves steeping compost in water for a defined period of time during which nutrients and microorganisms from the compost source are extracted.
- AACT is an “active” brewing process that introduces oxygen into the water and compost mixture via an air pump. NCT is a “passive” process made by simply mixing the compost and water and allowing them to ferment with little or no disturbance.
- AACT requires more equipment and knowledge to make than NCT.
- AACT can be produced more quickly than NCT. Brewing times for AACT can range from 18 hours to three days. The average NCT fermenting period is 14 days.
- AACT often has nutrient supplements and fermentation products rich in microorganisms (such as molasses, yeast extract or kelp powder) added during the brewing process to increase the beneficial microbes’ concentration in the tea. NCT does not usually have supplemental microbes.
- Because it often contains supplemental microbes, AACT is believed by some to introduce more microbial life to the soil and plants than NCT, although not everyone agrees.
It should be pointed out that academic research into compost tea is a relatively new pursuit and is ongoing. So many variables — quality and source of compost, quality of water, aeration, time, nutrient additives and so forth — can go into compost tea that comparison studies are difficult.
The main benefit of compost tea (whether aerated or not) is that compost tea amplifies solid compost into a dispersible liquid form that saves money by helping compost go a lot farther. Gardeners who make their own compost know that stretching that valuable commodity as far as possible is a very good thing. Another major benefit of compost tea is that it provides many of the benefits of solid compost to the soil much more quickly.
Both Jane Curtis and Daniel Millikin are big proponents of compost tea. “We’ve had proven success with the tea applications, and we would like to share our methods with the public,” Curtis said. “Since the McGovern Centennial Gardens have only been up and running for such a short time, we’re basically operating in survival mode at this point, but we definitely plan to provide educational outreach on using compost tea to our visitors in the future.”
In the meantime, why not plan a visit to Hermann Park and see the McGovern Centennial Gardens for yourself? It is a magical place, made even more so with the help of rainwater and compost tea.
Editor’s note: This article was scheduled for publication prior to the arrival of Hurricane Harvey. At press time, we are unable to determine the extent of damage, if any, the park may have suffered.