Imagine planting 37,000 perennials, laid out in a tapestry of matrix plantings, block groupings and shaded woodlands, while also dodging excavators on an active construction site. It’s business as usual
for Piet Oudolf and his team as they lay out his latest masterwork, Calder Gardens a new multi-layered cultural space in Philadelphia.
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This 1.8-acre landscape is in conversation with a new, low building with a tapered metal façade, and many works by renowned artist Alexander Calder that will rotate over time. The garden is unusual in its breadth and stature, cloaking the entire site, and in no way a backdrop to the architecture or sculpture.
On a hot day in June this year, Piet and his plant team arrived on the site to oversee installation, conducting percolation tests, co-ordinating plant deliveries, and pouring over rainbow planting plans of stunning intricacy. At this scale and level of complexity, an equally sophisticated planting process is required.
Piet’s team translates his designs onto physical land, all while competing for space with front- end loaders and irrigation crews – like painting themselves out of a room. The only thing that keeps this elegant ballet from descending into chaos is Piet’s layout process, developed over decades.
His plans are overlaid with a 3m-square grid. Once the hardscape, soils, grading, irrigation and percolation tests are complete, that grid is then measured and laid onto the landscape using fluorescent mason line. While many designers locate trees with stakes, Piet prefers to be onsite for their placement, directing adjustments and rotation with the understanding that many design elements change over time, but trees will be here long after we will.
Large organic shapes are spray-painted onto the soil as Piet’s team transfers the planting plans onto land. Two flags are then placed in each shape, labelled with the species, cultivar and number of plants planned for that space. Gorgeous, custom-grown plants in 9cm pots are arranged alphabetically around the perimeter of the planting zone. These smaller plants are never pot bound, and are easier to plant and acclimate to their new homes than those in large three-litre pots.
To move plants to their intended location, team members must grab a flag, collect the indicated plants, and place them on their shape to await arrangement. Spaces with plant combos have more flags and multiple deliveries. Plant arrangers then distribute plants within their space, most often at
30cm spacing, species depending.
Once block planting shapes are filled in, the scatter plants within the matrix are located on their spots, and the remaining matrix grasses – Eragrostis, Sporobolus and Schizachyrium – are carried over and distributed by landscapers.
Plants are planted by teams of landscapers using 75mm augers, watering each section as it is finished. Mulch is not used at this stage. Weeds in the seedbank are encouraged to sprout, recorded and pulled. That knowledge of mallows, oxalis and nutsedge is critical to long-term management. Composted leaf mulch will be applied in year two.
For many designers, editing is part of the layout process. But for Piet, shockingly few adjustments are made to the original planting plan.
Quantity calculations are nearly exact and unless paths and grading shift, plants are placed as written. Piet’s reputation as a designer is renowned, but there is much to be learned from his craftsmanship of landscape construction too.