The Green Team Part 7: From Field to Park

Orchestrating digging times and planting windows

In our previous post, “Tree Tag…You’re It”, we let you in on the details of what landscape architects call “tree tagging,” as well as my spring experience with tulip poplars, and some of the challenges we face in the field during the selection process. Here we discuss the post-tagging process.

The landscape architect’s job doesn’t end when she leaves the nursery. The trees we’ve selected must be maintained, cared for, and prepped in anticipation of delivering them to the project for installation. This multi-step process involves digging up the trees from the field, preparing each tree by its root condition, packaging, delivery, and finally, installation.

Digging Times

Digging trees is dictated by the calendar year and season, as well as by planned installation schedules, and even specific plant types.

IMAGE-2

Bald Cypress (Taxodium distichtum) trees tagged in the field are dug and balled in burlap by machinery in early spring, prior to the planting season.

Courtesy Mathews Nielsen

A tulip poplar (Liriodendron tulipifera), for instance, isn’t a picky tree, but others certainly are. Trees we call “fall dig hazards” drop their leaves well into the season—they don’t go dormant until very late in the fall. These finicky species include hawthorn, sweetgum, cherry, and pear trees.

IMAGE-3

Containerized trees in storage, waiting to be shipped to a project for installation.

Courtesy Mathews Nielsen

Order Up

Once the digging process is completed, our tulip poplars will be ready for delivery. This is not as simple as picking up a tree and throwing it on a truck; each tree and its roots differ in height and size, affecting the number of trees that can fit on a truck. More importantly, tree roots and canopies must be protected from damage and wind during trucking and watered to keep them from drying out. The idea is to mimic field conditions and keep the tree as evenly moist as if it were still growing in the ground.

IMAGE-4

Lombardy poplar trees (Populus nigra) in differing height and rootball size are placed on a truck for delivery.

Courtesy Mathews Nielsen

Next Step: Installation

Timing, a critical factor when it comes to successful planting, is geographically dependent. Typically, plant installation occurs during two seasonal windows, spring or fall, based on hardiness zones and frost potential. Planting windows also vary based on plant type—deciduous trees, evergreen shrubs, perennials, etc.

IMAGE-5-

A Zelkova tree (Zelkova serrata “Green Vase”) installed outside of the preferred planting window shows signs of distress.

Courtesy Mathews Nielsen

Tulip poplars are deciduous. In New York City, we prefer to plant them in the spring, from mid-March through early May or in the fall, from mid-October through mid-November. Similar planting windows also exist for shrubs, grasses, perennials, and bulbs. These specific planting times require that the contractor prioritize plant sequencing within the construction schedule to make the process proceed seamlessly. Even so, mishaps occur.

During a fall planting at a city plaza, we were called on site to review the installation of an 8-inch tulip poplar. As a crane lowered the tree into the planting bed, its trunk twisted slightly, causing it to torque and crack. The landscape architect and an arborist reviewed the wound and determined that the tree would likely heal itself, but that it must be monitored for an extended period and replaced at no cost to the owner should its health decline. In this case, the project moved ahead according to schedule—thankfully so.

IMAGE-6-

An 8-inch caliper tulip poplar (Liriodendron tulipifera), tagged for Mercer Street Plaza in Manhattan arrives by truck, ready to be unloaded by the landscape contractor.

Courtesy Mathews Nielsen

The next time you watch a poplar being lowered into a pit along Broadway, sit under an oak in Hudson River Park, or have lunch at the plane tree bosque at Lincoln Center, remember the planning and coordination that was necessary to get that tree there. Tagging. Digging. Rootball preparation. Delivery. Installation. It’s a finely orchestrated process.

Our next post will address another aspect of planting in urban spaces—going vertical.

IMAGE-7-

Tagged tulip poplars (Liriodendron tulipifera) wait patiently in the field for spring digging.

Courtesy Mathews Nielsen

Lisa DuRussel, RLA, ASLA, LEED AP is a Midwestern transplant, avid coffee drinker, soils enthusiast, and practicing landscape architect in New York City. Since receiving her BS and MLA from the University of Michigan, she has worked on numerous urban revitalization and cultural landscape projects in the New York and Chicago areas, including the Governors Island Park and Public Space project.

This is one in a series of Metropolis blogs written by members of Mathews Nielsen Landscape Architects’ Green Team, which focuses on research as the groundswell of effective landscape design and implementation. Addressing the design challenges the Green Team encounters and how it resolves them, the series shares the team’s research in response to project constraints and questions that emerge, revealing their solutions. Along the way, the team also shares its knowledge about plants, geography, stormwater, sustainability, materials, and more.

Recent Projects