The Green Team Part 5: Tree Tag…You’re It!

How landscape architects pick the perfect tree for a site.

In our last Green Team post, Planting for the Future, we described the importance of the planting environment in a comprehensive landscape design. Trees create the planting framework and structure for a site at the macro level, so their selection and placement are crucial aspects of the design process. This post is the first of two that describe what landscape architects look for when picking the perfect tree—we call this “tree tagging”—and some of the challenges we face in the field during the selection process.

Finding a Fit

After tree species are vetted for a project and the desired plant list is completed, there comes a time when a landscape architect moves out from behind her drawing set, turns off AutoCAD, and heads out to a nursery—“department stores” for plant materials—to examine trees growing in ground and to make selections. Typically, the designer is accompanied to the nursery by the landscape contractor, who acts as a liaison between the designer and the nursery manager to locate plant material specified for the job. Because plant availability ranges across nurseries and geographic regions, it is not uncommon for a designer to select and tag plant material from multiple nurseries, which can be a time-consuming—albeit crucial—process.

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A typical tree tag, locked on a honey locust (Gleditsia triacanthos cv. Inermis), showing the unique embossed number for record.

Courtesy Mathews Nielsen Landscape Architects

After a tree is reviewed, chosen, and tagged at a given location, the grower removes it from the nursery’s inventory, seals it, and locks it until it is ready to be moved to the project site for installation.

Window Shopping

And so on a cold morning early last spring, I was sent on a tree tagging expedition to a number of northeastern nurseries in search of a variety of the tulip poplar (Liriodendron tulipifera). Viewing trees in their dormant season is actually preferred, though not required, to get a true sense of the tree’s form without the influence of leaves. When tagging in the spring or summer, temporary blemishes on leaves resulting from drought, heavy rains, and winds are often evident, which could cause one to pass up a perfect plant.

En route to Long Island to attempt to tag 13 tulip poplars, I reviewed their characteristics: What is their typical form and habit? Straight trunk, pyramidal canopy. Typical branching structure? Pyramidal when young, becoming more irregular with age. Bark? Gray with lighter gray furrows. Leaf arrangement? Deciduous, alternately arranged, flag or tulip-shaped (but I was unlikely to see these at that time of year).

Arriving at the first nursery, I began to review the “blocks” of trees available. Blocks are planting rows organized according to species type, age, and variety.

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Honey locust trees (Gleditsia triacanthos cv. Inermis) planted in a block within a nursery. Trees are often planted on a grid to allow access to provide maintenance, apply chemicals, or dig the plants.

Courtesy Mathews Nielsen Landscape Architects

Installed at the same time, the blocks comprise groupings of plant materials of similar size. One section may house red oaks (Quercus rubra). Move down a couple of rows, and you might find a selection of London plane trees (Platanus occidentalis). Keep going, and you may discover a block of American elms (Ulmus americana).

I walked the rows of trees, taking note of those that I thought would make the cut. Evaluating these initial selections, I considered my typical series of basic questions: Is the tree the correct height or caliper? Is the plant of the general form one would expect for that variety? Is there an apparent single leader, or one branch that will obviously become the center trunk?  Alas, I found that my initial selections did not meet the size required for the project, so I refrained from tagging and moved on to the next nursery.

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Mathews Nielsen Principal Kim Mathews and landscape designer Johanna Phelps examine an American hornbeam (Carpinus caroliniana) in the field for caliper size.

Courtesy Mathews Nielsen Landscape Architects

At the second nursery, I noticed brightly colored tagging seals bearing the name of another design firm already locked to a number of trees. This happens often, as many design firms pull plant material from the same geographic pool. Even though poplar trees in our specified range were available at this nursery, I found they were too few in number from which to choose 13, so I set off for the next tagging spot.

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Don’t forget the shrubs! Even though the term “tree tagging” is related to trees, the landscape architect is also responsible for selecting shrub material. Here is a block of Chicagoland Green boxwood shrubs (Buxus sempervirens ‘Chicagoland Green’).

Courtesy Mathews Nielsen Landscape Architects

Hitting the Jackpot

The third nursery visit was a success. After I made initial selections, I measured each piece while concurrently evaluating branching structure and form, asking myself a series of more detailed questions: Is the branching pattern evenly distributed and free of crossing branches? Is the root flare at the base of the tree visible? Is the plant free of scars and are all pruning cuts healed over? Is it free of disease and pests? When my answer was “yes” across the board for a given specimen, I officially tagged it for future planting on the project site.

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As a general rule of thumb, watch your step, as holes remain where previously tagged trees (in this case, bald cypress, or Taxodium distictum) have been dug from the field. . . as are mud puddles, bugs, and poison ivy!

Courtesy Mathews Nielsen Landscape Architects

On Site

How do trees get from the field to the park? How are they prepared for planting, and are there any requirements for digging or planting trees? We will share more on the tagging process and address these additional questions in our next post, and we welcome your thoughts and comments on this one.

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Trees are now B&B (balled and burlapped), ready to be shipped to a project site.

Courtesy Mathews Nielsen Landscape Architects

This post is part of The Green Team series.

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 Metropolis blog post is one in a series 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.

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