Fall is the best time of year to view one of the Garden’s oldest, yet often overlooked collections. In a display that ranges from bright golden yellow to muted copper to deep scarlet, our trees and their fantastic fall foliage take center stage every October. In celebration of our colorful canopy, the Garden is kicking off Tree Week—offering visitors the opportunity to learn more about this impressive collection.
The Garden’s canopy is made up of more than 5,500 trees, and that’s just at the main campus in the City of St. Louis. The Garden’s Shaw Nature Reserve in Gray Summit has its own expansive canopy, showcasing the woodland habitat of our region. And there are tropical trees under glass both inside the Climatron and at the Sophia M. Sachs Butterfly House, located in Chesterfield.
The Garden’s collection is highly curated, multi-layered, and incredibly diverse. It includes towering Missouri-native pin oaks, small-but-showy star magnolias from Japan, and everything in between—representing more than 1,100 species.
While some trees date back to Henry Shaw’s time, it’s not a stagnant collection. “Maintaining tree cover in a garden is called canopy management planning,” says Andrew Wyatt, Senior Vice President of Horticulture and Living Collections. “Planting is staggered and strategic, so you always have new trees coming along to replace those that die.” The canopy management plan includes an increased focus on conservation. The Garden is already a home to a number of endangered or vulnerable tree species, and the horticulture staff works to identify threatened trees from around the world and add them to the collection.
Read more: Back from the Brink: Saving a Species on the Edge of Extinction
The collection is also curated on the needs of the plants below. For example, the leafy-green canopy of the English Woodland Garden is the perfect setting for a shade-loving understory. Plants that prefer to soak up more sun, like boxwoods, are grown in areas where tall trees cast only occasional shadows.
Taking Care of Our Trees
Just like the rest of the Garden’s living collections, trees need proper care to keep them healthy. Horticulturists use a multifaceted approach, beginning with something called a tree risk assessment. This is a health and safety evaluation of any tree that poses a potential hazard, especially where large limbs grow above a walking path. The data is used to identify the types of treatment needed and to prioritize a project list.
That’s where Tree Crew comes in. This group of Garden horticulturists works to maintain the largest trees in the collection. Supervisor Ben Chu, who has been taking care of the Garden’s trees for more than 30 years, leads the team. David Gunn handles the day-to-day execution. The rest of the team includes Garden horticulturists who volunteer their time on top of their day-to-day responsibilities. Like Chu and Gunn, other Tree Crew members have achieved Certified Arborist status through the International Society of Arboriculture.
Read more: Tree Crew Takes Part in Arborist Day of Service
Busy season begins in the fall and lasts into early spring. A typical day begins by loading up the gear—helmets, gloves, climbing rope, harnesses, hand saws, and chain saws. The crew gets access to the canopy through traditional harness climbing or with the help of a hydraulic lift. The lift allows safer, easier, and quicker access to the canopy.
Tree work may look cosmetic, but is always done with a goal in mind. Removing dead wood helps improve visitor safety and prevent internal rot. Thinning the canopy allows the understory plants to benefit from more sunlight. And pruning can influence tree architecture, while also promoting a more sound structure. The work can also be more drastic, such as removing large limbs or even taking down an entire tree. About a dozen trees were removed this past winter after showing signs of decline. Often a tree that looks healthy to the untrained eye from the outside reveals dangerous interior rot after being cut down.
While taking down a tree can be a dramatic change, Garden staff are also planting new ones all the time. More than 1,000 trees have been added to the collection in the past 15 years. Much like their older and larger counterparts, these young trees are also assessed for health and branching structure to make sure they will be part of the canopy for years to come.
Read more: Ask the Garden: Your Tree Questions
Protecting Our Trees
The Garden protects trees and keeps them healthy in ways beyond pruning and removing dead wood. Species at risk from pests and disease are often treated with the equivalent of tree vaccines, protecting ash trees from the emerald ash borer or elm trees from Dutch elm disease. The roots of some trees also get special care; air spading helps break up compacted soil, and a growth regulator helps trees divert energy from the canopy to building stronger roots.
The often unpredictable St. Louis weather is another ever-present threat to the collection. A tornado destroyed hundreds of Garden trees in the summer of 1896. Drought, heavy rain, and cold snaps can also damage the collection, especially non-native trees that aren’t adapted to local conditions.
More than 93 trees are outfitted with special lightning protection. Gamma Tree Experts generously provided protection for 63 of those trees, beginning in 2013. “We are proud to have provided the labor to protect these trees as a gift to the Garden,” says Tim Gamma, President of Gamma Tree Experts. “We’ve had a strong partnership with the Garden for many years, supporting tree maintenance. We aren’t a huge corporation, but this lightning protection is a significant way we could contribute to a place that means so much to our community.”
Nature, however, has a way of thwarting even our best efforts to protect our trees. This past spring, a storm brought down a European beech in the English Woodland Garden. A downed tree would usually be cut up, mulched, and used on Garden grounds, but this particular specimen will be left in place as an example of the natural life cycle of a woodland habitat.
Although our trees certainly look fantastic in the fall, there are plenty of reasons to admire this collection in every season. Winter provides a fantastic opportunity to appreciate the architecture of our trees—the twisting branches and textured bark laid bare by the falling leaves. Magnolia blooms and cherry blossoms herald the return of warmer weather each spring, followed by other flowering trees like dogwood and redbud. And in summer, escape the St. Louis heat under the shade of our leafy green canopy. The Garden’s tree collection is truly designed to be enjoyed year-round. You just have to remember to look up.
Cassidy Moody – Digital Media Specialist