Developing Alternatives to Chemical Pesticides and Fertilizers
Maintaining 250 acres of indoor and outdoor collections spanning over a million plants comes with its fair share of challenges. To address the threat of pests and disease among our plants and trees, NYBG works to maintain a proactive, green approach to chemical applications Garden-wide.
The Green Materials Recycling Center
NYBG horticulturists generate an enormous amount of compostable green waste as we care for the more than 1,000,000 living plants that grow across the Garden’s 250-acre National Historic Landmark landscape. Every blade of grass we cut, every weed we pull, every leaf that falls, and every twig or branch we prune is gathered, processed, and composted in our state-of-the-art Green Materials Recycling Center, which opened in late 2016. These “green materials” become the compost and mulch we apply to the landscape to promote healthy soils, suppress weeds, and reduce our dependence on chemicals. Composting and reusing our green waste rather than sending it to a landfill reduces the number of trucks on New York streets, decreases our carbon footprint, and limits our need to purchase and apply expensive and environmentally unsustainable herbicides, pesticides, and fertilizers.
Integrated Pest Management
More than 15,000 different kinds of plants grow in NYBG’s glasshouses, gardens, collections, and seasonal displays. In a leisurely late summer afternoon, a visitor can enjoy the glossy foliage and bright pink flowers of Cavendishia grandifolia (a rare blueberry relative from the Andes) growing in the Montane Tropical Rainforest Galleries of the Enid A. Haupt Conservatory; luxuriate in the shade of a 300-year-old white oak in the old-growth Thain Family Forest; and find their favorite of the dozens of dahlia cultivars on display in the Pauline Gillespie Gossett Plant Trial Beds in the Home Gardening Center. While all of this diversity makes NYBG the perfect place to celebrate the magic of the Plant Kingdom, it also presents a particular set of challenges for the horticulturists who care for the Garden’s plants.
To keep the Garden’s diverse plant collections healthy, NYBG horticulturists must be on constant lookout for the similarly diverse suite of insects, diseases, and weeds that makes the Garden home. When we find a problem, we employ the principles of integrated pest management (IPM) to address it. Quite simply, IPM stresses knowledge of the plants and the pests that afflict them—vigilantly monitoring to find problems while they can still be solved; using the least toxic means of addressing a problem once it has been identified; and evaluating the results of whatever approach has been chosen to promote plant health.
More often than not, the means of solving a problem with plant health at NYBG are cultural rather than chemical. Most plants can fight off insects or disease if grown in healthy soil and sited, irrigated, and fertilized properly. If improving cultural conditions does not address the plant health concern, then Garden horticulturists have an array of options at their disposal, including releasing natural predators such as lady bird beetles, applying a “tea” made from compost and other natural products, or, as a last resort, using the least toxic product available to address the specific problem.
That most visitors to NYBG are unaware of the complex give and take between the Garden’s plant collections and the pests and diseases that impact them is a credit to the efficacy of integrated pest management, and proof that one does not need to spray indiscriminately to have a healthy and beautiful garden.
Mature Tree Care
Nearly 30,000 trees, including thousands that are a century old or older, provide something to celebrate in every season at NYBG. Clouds of magnolia, flowering cherry, crabapple, and dogwood flowers float above the spring landscape, drawing visitors from the Garden’s gates deep into its interior. Ancient oaks cast dense shade in July and August, providing welcome respite from increasingly hot and humid New York summers. The electric oranges, reds, and yellows of sugar maples, tulip trees, and sweetgums in the Thain Family Forest rival those of northern New England forests in fall. The venerable pines, spruces, and firs in the Arthur and Janet Ross Conifer Arboretum remind us that the Garden is very much alive even in the dead of winter.
While their beauty alone would be enough reason to take special care of the Garden’s trees, the additional benefits they provide make their long-term survival all the more important. Collectively, the Garden’s trees remove hundreds of metric tons of carbon dioxide from the atmosphere each year and store tens of thousands of metric tons of carbon within their trunks, branches, and twigs. Our trees and Forest provide habitat for an astonishing array of wildlife ranging from Great-horned owls to mourning cloak butterflies, and even beavers.
Climate change, stresses inherent in the Garden’s urban environment, and a seemingly never-ending parade of new pests and diseases threaten the health of the Garden’s oldest and most majestic trees. To counteract these threats, NYBG arborists employ a range of techniques to keep the Garden’s mature trees healthy. Using compressed air and a tool called a “tree spade,” they alleviate soil compaction caused by decades of trampling feet and turf equipment. They incorporate compost into the soil to feed the fungi and micro-organisms that help tree roots absorb nutrients. They climb our trees, some of which are more than 125 feet tall, to prune out dead or damaged branches, install cables to protect against the loss of major limbs, and adjust lightning protection. An automatic irrigation system allows us to keep our mature trees well-watered during severe droughts.
Together these techniques and others help prolong the lives of the mature trees that are a defining feature of NYBG’s historic landscape. Planting new trees every year ensures that NYBG visitors will have the opportunity to marvel at ancient trees for generations to come.
When founding director Nathaniel Lord Britton and landscape architect John Brinley developed the General Plan for The New York Botanical Garden in the 1890s, they envisioned a picturesque landscape similar to that of the Royal Botanic Gardens, Kew, in London. Britton and Brinley’s design included a glasshouse, a library, display gardens, and encyclopedic collections of trees and shrubs, all set within expansive lawns. Although certain aspects of the Garden have changed since Britton’s time, these key attributes remain in place today.
To keep the Garden’s historic lawns healthy while reducing the use of chemical fertilizers and pesticides, NYBG horticulturists have implemented a new approach to turf care, which starts with establishing healthy soils. To promote soil health, horticulturists alleviate soil compaction with an air spade or tine aerator and make regular applications of compost tea combined with fish emulsion, kelp, and other organic products. This organic cocktail does an excellent job feeding the soil organisms that help make essential nutrients available to turf grasses.
Once the soil is healthy, we overseed with the best turf varieties for our climate. For decades, our seed mixes were dominated by Kentucky bluegrass and perennial ryegrasses. Modern best practices incorporate tall fescues, which are slower growing, disease resistant, and drought tolerant. Combined with improved bluegrass and perennial ryegrass varieties, tall fescues create lawns that green up early in spring and remain green in all but the most severe droughts.
The final steps to creating healthy turf are cutting high and leaving the clippings on the lawn. Cutting to a height of 3.5–4” helps the turf grass shade out weeds and prevents the removal of too much leaf blade at any one time. Leaving the clippings on the lawn returns nitrogen and other nutrients to the soil, reducing the need for nitrogen-based fertilizers, which are expensive and can lead to water pollution if not properly applied. Weeds are managed as needed where they appear rather than through large-scale applications of herbicides to all the turf.
To many Americans, a lush lawn is a symbol of prosperity, regardless of its impact on the environment. At NYBG we are making every effort to remain true to the historic design of our landscape while reducing the impact of our horticultural activities on the health of New York’s air and water. With sustainable practices in place, we know that our lawns are far more in keeping with our institutional commitment to the larger environment.
Organic Gardening Practices
In the Ruth Rea Howell Family Garden, we employ organic gardening techniques in the management of our site and we share our organic gardening practices with the participants in all of our programs, promoting these practices to tens of thousands of impressionable green thumbs each year.
Compost — All garden waste is incorporated into our composting station immediately adjacent to the Family Garden's main entrance, emphasizing just how important this practice is to the health of our garden. Visitors are invited to help to maintain our four-bin system and learn about composting best practices. Mature and screened compost is applied as a top dressing in our planting beds.
Mulch — In order to avoid the use of herbicides, we apply mulch. Layers of hay and wood chips are top-dressed into the garden beds to suppress weeds that grow in between our crops. This technique additionally helps to maintain consistent soil temperatures and prevents water loss, decreasing our demand for irrigation.
Crop Rotation — We rotate crops to minimize disease and balance nutrient consumption. This technique allows us to avoid the need for fungicides. As an example, we follow heavy nitrogen feeding plants, like those in the mustard family (broccoli, kale, kohlrabi), with plants that add nitrogen to the soil, like those in the legume family (beans, peas, clover).
Pest Management — We scout and observe our crops for pests and, when possible, remove pests by hand. We also groom crops, removing decayed leaves and stems to discourage disease advancement and to improve ventilation. This helps to prevent fungal diseases and thus avoid fungicides. We also plant trap crops to distract pests from our intended crops.
Cover Crops — We plant cover crops to add organic matter to our soil and to replenish nutrient levels, minimizing our need for soil amendments. The buckwheat planted this spring additionally provided a source for nectar and pollen to our honeybees.
Soil Amendments — In addition to adding compost, we apply various organic granular and water-soluble fertilizers, including soybean meal, fish emulsion, bone meal, and seaweed, using products recognized by OMRI and NOP as organic.
Beneficial Planting — We include plants that attract beneficial insects in our meadow garden. Beneficial insects include pollinators as well as insects that feed on pests. Wasps, lacewings, and ladybugs attracted to various plants help to control assorted pest populations, helping us to eliminate the need for insecticides.