Minnesota’s Largest Ever Public-Private Initiative Tasks Silva Cells with Bringing the Green

Ongoing $5.6 billion multi-phase project surrounding the world-renowned Mayo Clinic in Rochester installs Silva Cells in support of hundreds of trees


Consistently ranked as the top hospital in the United States, the Mayo Clinic treats more than 1.3 million patients from over 130 countries each year — and their campus headquarters and busiest hub is located in Rochester, Minnesota. Spearheaded by Destination Medical Center (DMC), a public-private economic development initiative launched in 2013, Rochester kicked off a multi-year landscape enhancement project in 2019. The objective of the $5 billion plan is to redevelop the city’s public realm to reflect the community-first mission of the clinic itself, bringing people together while boosting Rochester socially, economically, and environmentally. Green infrastructure was a priority from the outset: The mature growth and ongoing health of new tree plantings were vital components of Coen + Partners’ landscaping vision, which incorporated Silva Cells for their hardscape support and soil volume benefits — the system is providing on-site flexibility and lightly compacted soil to more than 150 trees, while simultaneously utilizing stormwater runoff for supplemental irrigation. The award-winning first phase of the project, Heart of the City, was followed by construction of the ongoing Discovery Walk, both stages installing Silva Cells for tree-growing optimization.

Installation Summary

Number of Silva Cells:  1,566 (3x and 1x)

Amount of Soil Volume Per Tree: 600 ft3 (shared rooting environment)

Number of Trees: 150+

Type of Project: Streetscape, Stormwater, Plaza, Municipal

Project Designer: Coen + Partners

Project Contractor: Bolander / Knutson Construction

Installation Date of Silva Cells: Late 2020 / Spring 2023

Mayo Clinic and Destination Medical Center

For seven consecutive years, the Mayo Clinic in Rochester, Minnesota, has been ranked the number one hospital in the United States — and, on the list of forward-thinking “smart hospitals,” it topped the list globally. More than a million patients visit the main campus in Rochester each year, a fact not overlooked by Destination Medical Center (DMC): a public-private organization that is spearheading a decades-long revitalization project with the goal of improving connectivity in the city’s public realm.

The largest government-private partnership in Minnesota history, DMC is a 20-year, $5.6 billion investment to position the state as a “global center for the highest quality medical care” — a component of which is bringing people together (patients, visitors, and residents alike) throughout the city, using public space for the public good.

The first phase of the project — known as “Heart of the City” — sought to do just this, rethinking the downtown space just blocks from the clinic. As noted by Landscape Forms, “Heart of the City… is true to its name, reinventing the city’s downtown core as a vibrant pedestrian environment that amplifies the true character of Rochester, invigorates civic pride, and sparks a new sense of community connection.”

The team at Coen + Partners was tasked with leading the landscape architecture design, retooling the car-centric streetscape and adjacent plaza to fit the new people-first public space objective. First Avenue (from Second Street to Center Street) and the perpendicular Peace Plaza at its center were the focus of Heart of the City, which began work in 2019. Local outreach was one of the first things Coen + Partners did, connecting with Rochester residents and businesses to instill a sense of collaboration for the project — indeed, more than 70 “pop-up” community events took place during the process.

In addition to creating an “elegant balance in design” and using landscape and pedestrian-friendly features to link the Mayo Clinic with the surrounding downtown area, sustainability was one of the top priorities of DMC and Coen + Partners, the latter identifying “cutting-edge sustainability strategies [to] promote greenery and reduce stormwater runoff and ice-melting salt usage.” As a result, more than 100 trees were incorporated in this phase of the project — and DeepRoot Silva Cells were used in support of them all.

Thousands of Silva Cells and Hundreds of Trees

“One of the client’s big goals around sustainability was to have substantial trees and tree growth. Sustainability was all about the ecological impact that trees can have — and how we can design spaces that promote social interaction.”

-Britton Jones, Project Manager at Coen + Partners

Green infrastructure was an important tool for Heart of the City project planners from the outset, recognizing both its environmental and social advantages. A total of 117 trees were planted in 2020, more than a hundred of which are found along the First Avenue streetscape where semi-mature, 6-inch-caliper trees were brought in from a nursery (another 15 new plantings are found in the pedestrian-focused Peace Plaza).

Investing in trees was of utmost importance, as Britton Jones (then Project Manager at Coen +Partners) observes: “It was really important to have a very robust tree canopy as early as possible to create that visual aesthetic and atmosphere, as well as the shade. It was important for the client to achieve this sustainability goal, so we felt the best way to do that — to ensure healthy trees — was to utilize Silva Cells.”

All 117 trees in Heart of the City are being supported by Silva Cells, more than a thousand in total. This is of particular importance for the 6-inch-caliper trees, whose semi-mature status made them especially vulnerable to transplant shock. The soil environment had to be carefully curated: In this case, a robust shared environment of lightly compacted soil was created by the Silva Cells. In fact, the system was able to work around one of the primary obstacles of this project: a duct bank running down the center of First Avenue’s eastern sidewalk. The location of this duct bank threatened to break apart the continuous soil environment: an impediment to healthy expansion of the roots over time. The DeepRoot technical team helped problem-solve on the fly, suggesting the 1x Silva Cell be placed above the duct bank to connect the soil space from each side, where the deeper 3x systems were installed. This guaranteed a large, unbroken soil bank for ongoing root growth.

Likewise, while there was not an official city-mandated stormwater element to the project, Silva Cells are also being used to help manage runoff at its source. The sidewalk pavement along First Avenue — which is heated to prevent the overuse of ice-melting salt, a stress on trees — is permeable, allowing stormwater runoff to seep into the Silva Cell soil below (which also receives water entering from roadway trench drains). This provides two benefits: supplemental irrigation for the trees and on-site cleaning and attenuation of the runoff before it enters the municipal sewer system. A win-win situation: dual-purpose green infrastructure at work.

The other planting area was in Peace Plaza: a multi-use pedestrian courtyard adjacent to First Avenue. A dynamic water feature is found at its center, which can be turned off to create more gathering and walking space as needed, with a foldout stage also available for events alongside custom-designed seating and furniture. Here, 15 new tree plantings were placed in Silva Cells to support them to healthy maturity, which will provide welcoming shade for area visitors.

“Zero Tree Loss”

“The tree growth has exceeded expectations. They’ve already multiple times had to do some tree trimming, which you wouldn’t typically see this early in the project.”

-Britton Jones

The investment in trees has paid off. Of the 117 trees planted, zero have died. As Jones notes, a typical urban project (especially one with pre-grown trees) would expect to see 10-15% tree loss. At Heart of the City? None. The trees are thriving — and have been from the very beginning, some of which have already grown from a six-inch-caliper size to an eight-inch-caliber size.

Thanks in no small measure to the successful implementation of Silva Cells at Heart of the City, they are also being incorporated into DMC’s second project stage: Discovery Walk, which is receiving its finishing touches now (in early 2024). Dozens more trees were planted in Silva Cells along this single-street project from the main downtown core to Soldier’s Field four blocks away. With its pedestrian-mall ambiance, Discovery Walk will be a multi-use corridor, accessible for vehicular traffic or outdoor events as needed.

Everyone is thrilled with these DMC initiatives thus far, particularly with the tree growth which has “exceeded expectations.” Keep an eye out for more stages of this ambitious, green-focused project in the coming years!

Project Awards

2023 National ASLA Award of Excellence

2023 Minnesota ASLA Award of Excellence


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