Landscape Design through Maintenance: Field Case Studies in Parametric Mowing

MEDIATING LANDSCAPE PROCESSES IN PROFESSIONAL PRACTICE

Change is an essential component of the landscape medium. In practical terms, the materials of landscapes move: water falls and washes its way downslope; earth compacts, erodes, and is deposited; and most vividly, plants grow, change with the seasons, and experience senescence. From an anthropocentric perspective, landscape is the product of how humans construct their environment (Jackson, 1984). As a social construct, its continuous evolution is subject to social practices, material needs, and aesthetic desires. The landscape architect’s job is to use these ephemeral concepts in designing a space in a current sociocultural and biophysical context, while accommodating future growth, entropy, and use (both human and nonhuman). Developing modes of practice that address these “processes over time” has become an imperative, especially in the context of landscape urbanism theory (Corner, 2006). Proponents of landscape urbanism “deploy ecology as a model of urban forces and flows” and attain the “ultimate urban figure… not through design but rather through the agency of ecological process directed towards cultural ends” (Waldheim, 2016: 165).

Nonequilibrium theories of ecology suggest that ecosystems are “open systems with no steady states … in which trends cannot be exactly predicted, and surprises should be expected” (Hill, 2005: 144). Because it “acknowledges management action must proceed in the face of uncertainty but facilitates iterative updating of knowledge and management strategies” (Rumpff et al., 2011: 1224), adaptive management has become an operative approach in restoration ecology. Early design competition proposals by the firm Field Operations adopted this approach (for example, Downsview Park, Fresh Kills). Since those landmark competitions, many landscape architects prefer to use the phrase “management, not maintenance” (Rainer & West, 2015: 61). In contrast, Woodward proposes simply “shifting the view of maintenance from an equilibrium [to a nonequilibrium] view, where the designed landscape may need to shift in the face of unplanned disruption but still survive” (Woodward, 2008: 98). Woodward’s interpretation allows maintenance to adapt with a changing landscape instead of creating a polemic that groups all activities to preserve stasis in the maintenance category.

Writing extensively about the emergence of the “process discourse,” Raxworthy (2013) advocates for a closer connection between landscape architecture and gardening. The ability for gardeners to respond to the novelty they discover through regular maintenance allows them to adapt to landscape changes in real time. Raxworthy (2018) coins the term veridic to describe the dynamic relationship between plant and gardener (contrasting with tectonic in architecture). This approach recognizes that:

1. “when we use plant material, our real material is growth itself” (Raxworthy, 2018: 5);

2. spaces change as plants mature; and

3. the form of a plant results from growth processes.

Engaging the veridic necessitates that landscape architects also acknowledge the importance of long-term maintenance of a planting design.

Unfortunately, most current professional models follow the linear structure of construction contracts, with limited opportunity for engaging ecological processes after installation of a designed landscape. For important liability reasons, designers have limited ability to direct the means and methods of construction (Hinze, 2010). Given the demands of a typical construction contract, landscape architects have one key opportunity to work with the novelty that emerges in landscape in real time: during the one or two years following final project implementation. This period is described as the “maintenance phase” of the construction contract (Woodward, 2008). Maintenance becomes a primary mediator of change in realizing the final landscape effect.

A key assumption during this phase is that if everything is maintained “properly” (that is, according to specifications), landscape change will match the designer’s intent. Although expectations of growth and maintenance often inform design decisions, the intent for a design may not match the reality of the newly constructed landscape. When undesirable changes emerge, they often appear as landscape maintenance “problems,” and resolutions require action by landscape architects with the assistance of the landscape maintenance contractor. This is similar to how a gardener reacts to novelty or the restoration ecologist uses adaptive management. Instead of pursuing maintenance as a means to an end, “landscape architecture might re-embrace maintenance to exploit the gap between intent and reality through a more place-based practice” (Davis, 2013: 305).

Maintenance presents an important opportunity for landscape architects to pursue and engage landscape change. Despite the connotation that landscape maintenance is solely focused on control and preservation, alternate definitions of “to maintain”include “to sustain, support or provide for,” “to continue or persevere,” and “to affirm” (Merriam-Webster, 2020). None of these definitions assumes stasis. I propose that the essence of maintenance is care. For a landscape to be maintained successfully, the associated maintenance operations are far more diagnostic and adaptive than they are thought to be—despite their pragmatic emphasis on efficiency. Furthermore, I propose that maintenance design allows landscape architects to engage the medium in a fundamentally different way, opening new opportunities for the profession—particularly in the territories of novel ecology, design activism, and landscape infrastructure.

Before proposing how maintenance could serve as a design instrument in landscape architecture, it is important to understand how maintenance operations mediate landscape. I introduce an approach to maintenance before presenting a series of field explorations that test these ideas through case studies exploring specific maintenance operations.

AN APPROACH TO MAINTENANCE

To maintain, from Middle French, is literally to hold in hand (Woodward, 2008), but the meaning varies considerably depending on what we are holding: a child, a motorcycle, or a lawn, for example. When maintaining something as dynamic as a landscape, it is through care that we identify how to enable a condition to continue being. As Robert Cook contends, connotations of preservation or restoration become much more complicated with landscape. “There is in landscapes the irrepressible biological vitality of living organisms struggling to survive. No amount of pruning can ‘preserve’ the form or material substance of a tree as it existed at one moment in time” (Cook, 1996: 43). According to Cook, the way to reconcile this misconception is with an understanding of “the landscape’s functional, organic nature” so that “the object of preservation then becomes less the material constituents and more the whole system in its present-day operation” (Cook, 1996: 51). This is almost identical to conceptual models in adaptive management, where the focus is on “restoration of the damaged ecological processes, not on reestablishing a specific plant community” (Stringham, Krueger, & Shaver, 2003: 112).

The most common misunderstanding of landscape maintenance is that it is the mechanistic repetition of the same operation over and over to suppress change in the landscape. Society has become so habituated to generic “mow-and-blow” practitioners who simply repeat the same operations at every visit that we incorrectly describe their work as maintenance. These actions are “cue[s] to care” (Nassauer, 1995), but they fall short when considering the level of care required to maintain a landscape in flux. Maintenance must adapt to changes in the landscape—from establishment through sustainment, preservation, and restoration—or the landscape fails, and we hear the common refrain that “it wasn’t maintained properly.” As the landscape develops, the maintainer must identify and diagnose what has changed, calibrate maintenance practices appropriately, repair elements that have failed, and sometimes add new elements to enable the landscape to “ carry on.” These operations demonstrate how maintenance is a creative act of care.

Mowing a lawn is perhaps the most obvious form of landscape maintenance—and is often pointed to as the paramount example of human control over nature—the lawn mower being the instrument that we use to suppress novelty (Pollan, 2008). Even the lawn mower must adapt to the lawn if the latter is to be correctly maintained. For example, adjustments to mowing height and schedule based on seasonal growth rates are needed; mowing pattern and direction must be alternated to cut each blade of grass evenly. Based on these parameters (and the particular microclimate and soil characteristics), a lawn will diversify to include other naturalized grasses and broadleaf species until a “ climax lawn” is established (Voderberg & Kowalewski, 2014). Mowing does not happen whenever we want—it is a transitory mediation with the cultural ecology that has emerged in the inches below the mower blade. Between and across mowing events, the landscape exists in a perpetual state of becoming.

This analogy provides a window into the generative capacity of maintenance. It also raises the question of how a landscape might evolve in response to its mowing regime. Individual plants may turn over like blades of grass and new ones, such as daisies, may be generated without the emergent whole becoming a different entity as long as its essential qualities and outward appearance remain. A landscape can also reach a tipping point, or radical difference, through maintenance, when “changes in the assembly and operation of instruments introduces a radical change and fundamentally alters the landscape itself” (Davis, 2013: 303). This is apparent in comparing the effects on a turf maintained by sheep, scythe, or riding lawnmower. These mowing regimes have:

1. ecological differences based on the botanical tolerances of plants to the disturbance of the cutting instrument, the subsequent growth response to this form of pruning, and the nutrient inputs into the field from manure or clipped vegetation;

2. spatial differences arising from the relative precision of each instrument, the visibility of broadleaf herbs following each cut, and the presence of manure or clipped vegetation; and

3. formal differences due to the presence (or lack) of instrument patterning and duration of the maintenance event.

A maintenance design practice is not a substitute for new landscape construction, as maintenance and construction engage the medium of landscape in fundamentally different ways. Maintenance design emphasizes an “aesthetics of thrift” (Dee, 2010: 22) governed by the parameters of maintenance tools and techniques, and a flexible, incremental adaptation of the landscape through direct action. By grounding design in the social practices of landscape maintenance, landscape architects can increase the resilience of their work and pursue landscape projects that may lack the funds for a capital improvement. Transportation departments, ports, dredge operators, and public utilities are making public and private landscapes through maintenance decisions at enormous scales. These infrastructural services form the basic organizational structure of the cultural landscape, the “background for our collective existence” (Jackson, 1984: 8). “Public works” more aptly describes the extent of these operations.

For shrinking cities with a lot of vacant land, the annual “care” mowing of abandoned lots reflects the perceived essentiality of mowing. Why not just allow a forest to reclaim the city? One would be hard-pressed to find the original lawn in these “ cosmopolitan urban meadows” (Del Tredici & Pickett, 2010: 21). Yet every year public works departments pursue “vegetation control” to show that they have not neglected their city. Alternatively, landscape architects could critically evaluate the maintenance practice of mowing to develop techniques that “take care” of these cosmopolitan meadows instead of suppressing their emergence. Such assertions assume that there are sufficient “cues to care” that make “the novel familiar and associate ecosystems that may look messy with unmistakable indications that the landscape is a part of a larger intended pattern” (Nassauer, 1995: 167). Indeed, “taking care” and “maintaining” can be used interchangeably. If landscape architects acknowledge that the essence of maintenance is care, landscape maintenance becomes increasingly specific, adaptive, and inventive.

PRECEDENTS FOR DESIGN EXPLORATION THROUGH LANDSCAPE MAINTENANCE

The theoretical implications of maintenance have proven to be fertile ground for artists such as Mierle Laderman Ukeles. Coinciding with the birth of her children, Ukeles first outlined her philosophy in the “Manifesto for Maintenance Art 1969!” Her proposal for an exhibition titled Care described herself as a “mother/maintenance worker.” She declared, “my working will be the work,” meaning that through the maintenance of her household, she will create works of art (Phillips et al., 2016: 211). Two of her earliest works are landscape exhibitions. In “22—Fall/Suite,” and “Time Slices: The Trees Are Having Their Period: Making a 50-Foot Sanitary Napkin for a 100-Year-Old Tree,” Ukeles links the fall of deciduous leaves—and their subsequent cleanup and removal—to the female body and birthing process as well as the social practice and material culture of waste. Through these explorations, Ukeles links feminism to labor. Recognizing that maintenance “ confers low status on anyone, regardless of gender, wherever it occurs, and also at the same time confers invisibility … [service work] provides women as a political class … a ready-made set of allies across all racial and sex lines for reorganizing this world” (Phillips et al., 2016: 7). This alliance eventually inspired her to become the artist in residence at the New York City Department of Sanitation.

Ukeles’s work frequently highlights the performative qualities of maintenance and choreographs everything from mops and rakes to garbage trucks and snowplows. From 1983 to 2012, Ukeles composed seven “work ballets,” which demonstrated the aesthetic potential embedded in the operational logic of our tools. Navigating heavy machinery through the constructed landscape requires training and finesse. Ukeles studied these maneuvers in detail and created a work of art by choreographing behaviors that represented purely functional acts. Teresa Gali-Izard has since adopted this formal aesthetic in many of her landscape designs, most notably in the D38 Garden, the Cantarell Garden, and her unrealized Valencia Central Park Competition entry (Arquitectura Agronomia, 2020).

The performances in Ukeles’s ballets are quite sophisticated. For example, the Snow Workers Ballet (2012) tells the story of Romeo and Juliet using snow removal equipment. It highlights the skill of maintenance workers and the pride they take in their work, even though they serve as invisible infrastructure with odd shift schedules and thankless responsibilities. In reframing maintenance as choreography, Ukeles reveals that it is not always necessary to hide these activities from the public. They are, in effect, ephemeral public events. Relegating maintenance to a particular class obscures the dance that happens around all of us each day. By valuing the performance of maintenance, we can increase the care of our public landscapes.

This connection to class enables consideration of landscape maintenance as a form of design activism. When denied the opportunity to purchase a home in a white neighborhood because of racist allegations that he would not be able to “take care of his yard,” vernacular (or folk) artist Pearl Fryar developed an interest in gardening. After successfully purchasing a home elsewhere, he collected discarded plants from local nurseries with the goal of winning an award from the Bishopville, South Carolina, Garden Club. A self-taught horticulturist, Fryar relied on certain conventions in the design and maintenance of his residential garden. In many ways, the garden’s structure follows the American vernacular in its use of hedges, lawn, and trees to order the yard. The novelty of Fryar’s garden emerged in his improvisations while hedging. His work created surreal and spectacular topiary with plants not commonly used in this tradition (Galloway, Pierson, & Fryar, 2006) (Figure 1).

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Figure 1

The vernacular landscape art of Pearl Fryar’s garden. Bishopville, SC. Photograph by author, 2011.

Labeling Fryar’s work as “topiary,” “sculpture,” or “hedge-trimmer gardening” does not quite describe what is actually occurring. Fryar created his landscapes through maintenance, seemingly without a predetermined form. These forms emerged through the care and attention given to the unique growth of each plant, “hand in hand,” just as maintenance must always be in dialog with a growing landscape.

A landscape designer most closely allied with this type of thinking is Gilles Clément. Like Fryar, Clément also “ gardens” with power tools and practices a high degree of specificity in his maintenance. Clément’s instrument of choice is the string trimmer, which he uses to maintain human movement through his wild garden, the jardin en mouvement. Although some of his plants were intentionally placed, his garden emerged primarily through maintenance and is composed of many ruderal plants that migrated from the adjacent abandoned spaces he calls the third landscape: “the totality of all those places abandoned by man” (Clément, 2015: ix). This is a play on John Dixon Hunt’s concept of third nature, the perfected nature of the garden (Hunt, 2000)—but flipped on its head. In the Third Landscape, the garden has gone feral to create novel, intermingled forms of wil-derness that are distinct from primordial wilderness (first nature). Instead of taking a restoration approach, Clément sees this space as a reservoir of biodiversity that should be integrated back into the garden through maintenance. This is in line with Peter Del Tredici’s approach to spontaneous vegetation, which recovers Frank Egler’s concept of intaglio to edit aggressive, unfriendly species while maintaining nonnative species that are providing ecosystem services (Del Tredici & Pickett, 2010: 22).

The discoveries made in Clément’s experimental garden have led to the development of a larger conceptualization of novel ecosystems through his theory of the Planetary Garden (Clément, 2015). Whereas novel ecosystems, “by virtue of human influence, differ from those that prevailed historically [and have] a tendency to self-organize and manifest novel qualities without intensive human management” (Hobbs, Higgs, & Hall, 2006: 58), Clément understands that humans have accelerated an intermingling of species across similar biomes to create new “assemblages.” Planetary gardening uses two principles—“observe in order to act” and “work ‘with’ whenever possible, ‘against’ as little as possible”—to describe a new paradigm of global stewardship that departs from the manage/preserve binary (Clément, 2015:34). These two principles are germane to a care-based maintenance practice that adapts to changes in the landscape while conserving labor. If the jardin en mouvement is the prototype, gardening “within the limits of the biosphere” can be achieved through a new approach to landscape maintenance, which is already scaled up to the level of public works (Clément, 2015: ix). Mowing is a familiar form of yard care, but also essential in the maintenance of infrastructural easements for example (albeit with larger machinery). Creatively engaging mowing as a dynamic design instrument allows landscape architects to jump the garden fence and produce planetary effects.

METHODOLOGY: MOWING PATTERN EVALUATION

Just as the previous artists, gardeners, and designers constructed novel landscapes and explored theories of maintenance through real-time action, I engaged in research by design to understand the generative capacity of maintenance as a design instrument in landscape architecture. A “constructivist” method of research through designing was identified as particularly well suited for this research to “generat[e] new ‘insights or constructs’” instead of testing the efficacy of an individual technique (Lenzholzer, Duchhart, & Koh, 2013: 123). Borrowing from the “design-related-research” methodology described by Steffen Nijhuis and Inge Bobbink (2012), I used design research through planning and comparative analysis to conduct experimental design studies and field trials as a learning loop.

Although this methodology can be applied to many maintenance activities, mowing was the focus of my research because it is the operation most associated with landscape maintenance and has the strongest connotation of preservation and control. As design research, mowing operations were analyzed and diagrammed to understand their basic parameters and formal logic. During experimental design study, these parameters were overlayed to explore their operational efficiency (economy) and aesthetic potential (cue to care). These designs were then applied through full-scale field trials to allow for direct observation of the mowing operation and its effects on landscape development. The insights generated from early yard-scale mock-ups led to further design research, research by design, and field trials on larger sites. To represent this process, three patterns are discussed in this article. Greater documentation is given to the third pattern because it is the final technique developed through this design-related-research methodology and has graduated from mock-up to large-scale field trial.

Altogether, the field trials took place on 10 different sites ranging in size from 400 square feet to 4.5 acres. The primary criteria for site selection was the landowner’s willingness to make their property available for field experimentation. In every case, this accommodation was made in the hopes of reducing maintenance—or achieving a more desirable result from the same amount of labor. Mowing pattern selection occurred after observing existing site conditions with the landowner and identifying the particular conditions that needed to be maintained. These conditions could be ecological (absent invasive species, for example), spatial (clear fire breaks), and/or aesthetic (the site looks cared for). Despite these simple selection criteria, the sites shared the following characteristics:

• Intended to be a field or a lawn (i.e., mainly herbaceous).

• Mown just enough to suppress woody species (usually one or two operations a year).

• Increasing presence of broadleaf “weeds,” perhaps because of the limited mowing regime.

• Near enough to the author’s residence to allow for regular site observations.

These sites have all evolved following a reduction in mowing, highlighting the effects of mowing on the landscape. For this reason, the design potential of the mowing regime—and a new approach to maintenance—is more explicit.

To record site observations before and after the large-scale field trials, this methodology followed a precedent from the Alnarp Landscape Laboratory, founded in the early 1980s at the Swedish University of Agricultural Sciences (Gustavsson, 2016). To document their creative management experiments, Roland Gustavsson and his research team conduct “monitoring by drawing” in addition to traditional plant surveys (Gustavsson, 2016: 88). This method uses architectural sections, or “profile diagrams,” in addition to photographs to illustrate how an initial forest condition responds to thinning over time. Using a familiar orthographic projection to communicate results helps landscape architects understand the changes that come up through management, the spaces created through pruning, and the ecological relationships among plants over time. Because of the relatively low height difference between herbaceous species across the large site area, the documentation method used in this article deviates from Gustavsson’s in that mowing operations were charted in plan and diagrammed in an axonometric projection. Photography has been included to illustrate the relationships represented in section drawings.

Parametric Maintenance of Mown Landscapes

Landscape maintenance shapes vast areas of the United States. As such, maintenance functions as an infrastructural service to prevent vacant lots from becoming “overgrown.” In this context, society often overlooks the ecological benefits gained from spontaneous vegetation and perceives it negatively as a sign of blight or neglect. Nassauer identifies “mowing” and “big, bold patterns” as two cues to care that “frame more novel ecosystems in inhabited landscapes … with clear signs of human intention” (Nassauer, 1995: 167–68). To explore these two cues, I cataloged conventional mowing parameters to understand their formal potential to pattern spontaneous vegetation through the economy of maintenance.

Parameters associated with mowing machinery

By identifying and understanding “the parameters” of mowing, we can translate its formal logic into a design language that is rooted in the function and meaning of the operation (Figure 2). The operation of the mower governs its width, turning radius, speed, and mowing height. These operations produce formal, spatial, and ecological effects:

• the width of the mower leaves lines in the landscape;

• unless a zero-turn grooming mower is used, the turning radius creates filleted corners and islands of unmown vegetation when making 180-degree turns;

• continual speed encourages driving in straight lines, softening curves over time;

• the mowing height promotes or discourages plants based on their botanical tolerance to cutting.

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Figure 2

The “rules”of mowing: parameters that govern equipment operation.

Parameters associated with mowing pattern

In addition to these mechanical parameters, herbaceous landscapes are mown using several different “tool paths,” which were diagrammed based on the author’s experience maintaining landscapes and researching online farming forums (Figure 3). Although most of these typologies are familiar, some are uncommon. From this design research, we see that patterns evolved by overlaying tool paths to create “orderly frames” around the “messy ecosystems” of cosmopolitan urban meadows. As an initial study, all patterns were tested in yard-scale mock-ups to test their operational feasibility and aesthetic qualities. Although the radial and perimeter tool path patterns share similarities in appearance, they are distinguished by the fact that the latter deals only with field edge conditions.

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Figure 3

Typical “tool paths” that determine the formal logic of mowing.

FIELD CASE STUDIES

Mowing Tool Path Variations

Hedgerow

With an orthogonal tool path, a large “turn-around” maneuver is required to account for the turning radius of the mower (see Figure 3). This reduces operational efficiency for several reasons:

1. a significant area is required to make the maneuver;

2. speed is reduced to tighten the radius;

3. islands of unmown grass are left on the interior of the radius; and

4. several more perimeter tool paths are required to clean up the edge.

Zero-turn grooming mowers were invented to counter these inefficiencies, but they are not suited for cutting tall vegetation or woody plants. A potential precedent for resolving this problem is found in the operation of an ice-resurfacing machine to recondition ice on a skating rink. At the start of the operation, a resurfacing machine requires only two passes around the perimeter of the ice arena to account for its turn-around maneuvers. Subsequently, the operator sweeps alternating strips longitudinally across the interior of the rink and then doubles back on itself to sweep the remaining strips on the return to the starting point. The additional width between strips reduces the size and difficulty of the turnaround maneuver and thus the number of initial perimeter passes required to account for the wide turning radius. In the context of field mowing, reducing the incidence of tool paths near the perimeter can result in significant time savings because comparatively larger areas are circumnavigated. Eliminating a “return-to-home” trip adds to the efficiency. Greater skill is required to ensure that rows are straight and properly spaced to cut entirely on the return path.

The hedgerow pattern is created by completing only the first pass of the alternating strip tool path so that the field is left with alternately mown and unmown rows (Figure 4). Because each pass is an offset of the previous one, the form is largely determined by the layout of the site and the alignment of the first cut. The most significant decision is whether the first pass follows a rectilinear or curvilinear edge because this has operational and aesthetic effects. Straight lines are simplest to execute but difficult to maintain in a perfectly orthogonal pattern. When rows arc, the mown strips disappear in the distance, but maintaining an offset is more difficult, so it is only economical on sites with irregular boundaries. If the initial vegetation is very high, the mower must be as wide as the vegetation is tall for the strips to be visible.

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Figure 4

Using the operational efficiency of the alternating strip pattern tool path, the hedgerow creates bands of unmown vegetation and is the foundation for subsequent patterning. Site photos are selected to represent this “first pass”on three sites before more advanced patterns were created. Upper right: Charlottesville, VA (400 square feet); lower left: Oregon City, OR (2 acres); and lower right: Eugene, OR (2 acres). Photographs by author, 2013–2018.

The alternating strip pattern can accomplish a variety of objectives when resources do not allow for a complete mow. The remaining rows have the agricultural aesthetic of strip farming, which mimics a field cropping pattern, making the remaining spontaneous vegetation seem more familiar. Because only half of the field is mown, this pattern reduces labor by a similar amount—excluding drive time and equipment setup. On a return visit, the operator can “switch” rows to ensure the field is completely mown by the end of the season or mow the same pattern as before to allow succession to continue in the unmown bands. A historical precedent for this strategy exists at the French baroque garden of Château de Courances, where rows are cut through new forest “to reduce the competition between trees and regenerate spontaneous vegetation” (Raxworthy, 2018: 59). Most significant for this research, the hedgerow became foundational for more advanced pattern development.

Field Moiré

After rows are established as guidelines, more patterning is possible to frame emerging vegetation. The field moiré recognizes that if mowing seeks solely to communicate care, a graphic approach to maintenance may deliver the same message as a blanket mowing. A field moiré can be created by executing a second hedgerow pattern approximately perpendicular angle to the first, generating a grid of unmown plots (Figure 5).

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Figure 5

Beginning with a weed-dominated “lawn,”hedgerow patterns are overlaid perpendicular to one another to create a field moiré effect in a yard mock-up. Flowering species include self-heal (Prunella vulagaris), common dandelion (Taraxacum officinale), and common violet (Viola odorata). Charlottesville, VA (400 square feet). Photograph by author, 2013.

The moiré effect is especially pronounced when the site is curvilinear. If the site is flat, the pattern will read as a simple grid. As with many approaches to landscape design, the pattern is less apparent from ground level and becomes bolder when the viewer is looking down from an elevated perspective. If unmown vegetation is very tall, the pattern may only be legible when viewed from an aerial perspective.

Based on the early yard mock-up of field moiré, the pattern is particularly successful in showcasing the floral qualities of herbaceous, broadleaf species commonly found in feral lawns. In more domesticated settings, it could also be used to highlight these qualities in nontraditional turf mixes, such as the Fleur de Lawn.

In contrast to the long strips of the hedgerow, the “occupiable” frames of field moiré allow for more human movement around each plot and a closer examination of what is emerging. This is more important if the remaining vegetation is very tall and the site is large, thereby limiting opportunities to walk between rows. Providing fluid access across the landscape can be an important factor for passive recreation on public sites. Compared with the Courances precedent, a field moiré can also make it easier to care for the spontaneous vegetation growing in each plot because the pattern provides access from four sides.

As with the hedgerow pattern, the field moiré grid can be mown over for a fresh canvas or maintained as garden plots. Unlike the previous pattern, the labor savings depend on staggering the schedule of each mowing. If both passes are completed on the same day, field moiré reduces labor by only 10%, although the time savings can be increased if wider strips are left unmown.

Drift

The previous two patterns are defined largely by site boundaries and equipment parameters, regardless of plant ecology. Without aggressive, toxic, or otherwise unfriendly species, it may be desirable to simply pattern a site and allow succession to occur. This laissez-faire approach may not be appropriate when certain undesirable species are present. In the Pacific Northwest, vacant lands are often mown to prevent the establishment of Himalayan blackberry (Rubus armeniacus syn. procera). Originally introduced for berry production by horticulturalist Luther Burbank, it escaped from cultivation in the 1920s. Its great vigor proved very well adapted to coarse Willamette Valley soils and summer drought. In this setting, it often captures abandoned land in a state of arrested plant succession (Burbank, 2009: 14; Caplan & Yeakley, 2006, 2010). Ultimately, the thorns of R. armeniacus make it an unfriendly plant for humans, so fields are mown annually to suppress the aggressive nature of this plant and every other plant that is growing alongside.

To target undesirable species, the drift pattern was developed. Using the hedgerow as a framework, the operator drives between unmown rows to survey what is emerging in each one, and cuts into the unmown row when a target R. armeniacus species is spotted. While ordering the field into rows makes it much easier to discern the distribution of target species, drift mowing still requires greater skill than the previous two patterns and relies on the plant identification abilities of the machine operator. In the case of the Himalayan blackberry, the dark green leaves and tall, arcing canes contrast strongly with field grasses. Flowering perennials—like Queen Anne’s lace (Daucus carota)—can also be identified when in bloom. Differentiating between target and nontarget grasses can be extremely difficult.

The remaining unmown drifts become a chart of plant distribution and instrumentation, linking the ecology of the field to the technology that maintains it. Remaining vegetation consists of the nontarget species, shelter that would otherwise have been eliminated by a blanket mowing, and the surprising spaces created by selectively cutting the target species. Only a few unmown drifts may remain if the target species are ubiquitous, as was the case in an Oregon City trial (Figure 6). Conversely, the initial hedgerow pattern remains dominant if the target species are absent from a large area, such as at the University of Oregon (Figure 7).

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Figure 6

Adapting the hedgerow drift pattern to specifically target the Himalayan blackberry (Rubus armeniacus syn. procera) and Queen Anne’s lace (Daucus carota). These two species were so ubiquitous, only isolated drifts remained after mowing. Oregon City, OR (2 acres). Photographs by author, 2017.

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Figure 7

A 2-acre demonstration completed by the author at the University of Oregon campus used the drift pattern to suppress Himalayan blackberry (Rubus armeniacus syn. procera) and fire risk. Several distinct spaces were created including (from top right): wide clearings, staggered drifts, and intact hedgerows. Eugene, OR. Photographs by author, 2018.

The directionality of the mowing reflects the geometry of the site, with views of the field appearing completely unmown from some perspectives and highly patterned from others. Skill in creating the initial unmown rows is critically important for this pattern. They should be slightly narrower than the mowing deck to ensure that the entire unmown band is cut when the operator steers in. Furthermore, the remaining drifts should be longer than they are wide to ensure they create big, bold patterns. If the hedgerow pattern is identifiable in the following year, succession can continue in the unmown drifts. If not, the operator can begin again from a new angle to create a moiré of plant succession in the unmown drifts.

An initial pilot study was completed by the author on a former quarry and landfill at the University of Oregon campus. It tested the capacity for drift mowing to achieve the maintenance goals of suppressing blackberries and fire risk while serving as a cue to care. No public complaints followed the demonstration, and it has since led to a multiyear five-acre field experiment. Unlike all previous trials, a third-party contractor who is directed by the author in consultation with UO Campus Planning and Facilities Management now conducts the mowing. According to personal communication with the contractor, the drift pattern takes about the same amount of time as blanket mowing—but is a lot more interesting.

As drift explorations moved from “demonstration” to “field exploration,” the documentation method shifted to include a botanical survey and a chart of the remaining drifts (Figure 8). This process also highlighted the potential utility of drift mowing as a survey method. Plant emergence in unmown rows allows for botanical surveys to take place throughout the growing season, and species identification is easier when plants can flower. Furthermore, the difference between the cumulative length of unmown rows left after the hedgerow pattern (first pass) and the cumulative length of unmown rows left after the drift pattern (second pass) approximates the overall distribution of the target species. This metric depends on the operator’s skill but can be compared over several years to evaluate the efficacy of the pattern. Although this ecological research is incomplete, maintenance is now used as a design instrument to guide the growth of the campus landscape.

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Figure 8

Chart documenting unmown areas after the drift pattern was completed by a mowing contractor in 2019 on the University of Oregon campus. Research on the ecological effects of this method is ongoing.

PRINCIPLES OF MAINTENANCE DESIGN

Implications of the field explorations discussed in this article present a range of potentially pursuable mowing opportunities. These case studies are not a mowing manual. Rather, they constitute a method of designing landscape through maintenance. Synthesizing the findings of this research involved a comparison of field observations with the initial theoretical inquiry to establish a framework for using maintenance as a design instrument in landscape architecture. The acts of creating and implementing the mowing design patterns in the landscape informed the theoretical inquiry. Following are four principles to guide practitioners in pursuing the scope of this work.

AUTHOR CONTRIBUTION

Michael Geffel is the sole author of this article. He conceived of the presented ideas, designed the study, carried out the inquiry, and developed the theory.

PEER REVIEW STATEMENT

This submission was peer-reviewed by three peer reviewers selected by the Editorial Office. Their contributions are gratefully acknowledged and appreciated.