Our Bonsai—and their display—are back and better than ever

Over the past two years, “When will the Bonsai Pavilion open?” was the top question Arboretum visitors posed to our plant production staff at the Dana Greenhouses. Like many museums and gardens, the Arboretum closed indoor spaces and confined outdoor exhibits like the Bonsai and Penjing Pavilion during the COVID-19 pandemic to ensure public safety. While providing top notch care to this beloved collection of dwarfed, potted plants remained a top concern over the interim, interacting with inquisitive visitors and sharing knowledge with bonsai enthusiasts is a pleasure we desperately missed. As pandemic guidelines changed and Arboretum staff began returning to work onsite, we were relieved to gain approval from health and safety officials at the University to reopen the pavilion to visitors in July 2021.

What happened behind the scenes during all that time? With the plants off view, we found an excellent opportunity to focus more of our attention on the exacting care and development of the collection with expert help from new bonsai specialist Jun Imabayashi. Jun started working at the Arboretum in March 2019, exactly one year before the onset of the pandemic. Although a native of Japan, he only became interested in bonsai while traveling abroad and viewing magnificent specimens displayed in other countries. Inspired, he returned to Japan to learn the art of bonsai and become an apprentice. After apprenticing for six years, Jun came to the United States, to apply his skills where bonsai practice is appreciated as a modern hobby and art form.

Spring 2020 will be remembered as “The Great Repotting,” as Bonsai Specialist Jun Imabayashi repotted nearly the entirety of the collection in less than two months. Here Jun combs out roots and washes off soil of a pauper’s-tea (Sageretia thea) during the intensive process. Tiffany Enzenbacher

When first introduced to the extraordinary Arboretum collection―including the thirteen specimens remaining from the original Larz Anderson bequest of 1937 and 1949―it was impossible for Jun to undertake much repotting, one of the most pivotal aspects of care for these containerized trees. Repotting typically occurs in early spring as the plants emerge from their winter dormancy in cold storage, and there simply wasn’t time. As a result, Jun spent his first growing season at the Arboretum observing, studying the history of the collection and its past care, and making fertilizer adjustments and styling improvements. Nevertheless, rejuvenating the roots and improving soil conditions remained crucial for many of the specimens, making 2020 prime time for “The Great Repotting.”

Repotting Hinoki Cypress
Bonsai Specialist Jun Imabayashi waited to repot the largest Hinoki cypress (Chamaecyparis obtusa ‘Chabo-Hiba’) until April 2021. Jun remarked that his 10-hour session with the 1799 specimen was the most difficult repotting of his career—the sheer size of the approximately 350-pound plant combined with freezing temperatures and snow made it especially challenging. Here former Director of Operations and Bonsai Curator Steve Schneider, Jun, and Greenhouse Horticulturist Chris Copeland lift the tree carefully out of its container so Jun can begin the repotting process. Tiffany Enzenbacher

As the hours, days, and weeks after repotting are so critical and potentially stressful for both the plants and their caretakers, our greenhouse facility was treated like an intensive care unit. Jun devised and directed a vigorous maintenance schedule, which included checking on individual plants up to six times daily. “Ninety percent of bonsai die due to lack of water,” Jun had explained. “Once you put [a plant] in a pot, it’s a person’s responsibility to water.” Since “The Great Repotting” occurred after COVID-19 safety measures had both reduced our staffing at the greenhouses and closed the exhibit to onlookers, we outfitted the structure with timed misters to alleviate such frequent manual watering.

Before and after images of our repotted 1799 specimen of Hinoki cypress. On the left, the tree has been removed from its pot, and Jun has combed out and removed excess soil from the top half of the root ball. At right, later that same day, repotting is complete and the tree has been moved back into the greenhouse for acclimation. Tiffany Enzenbacher

Last June, just before we reopened the pavilion to the public, I assumed oversight of the bonsai and penjing collection as its curator. My first concern was accounting for each of the 72 invaluable specimens that comprise our collection, working to inventory and catalog our current holdings and labeling each specimen in the Arboretum’s plant records database. Plant Records Manager Kyle Port printed anodized aluminum accession labels for plants not already bearing one, and together we designed and commissioned all new display labels for the pavilion.

With the plants repotted by Jun and their curatorial information and labeling well in hand, we turned our attention to the exhibit itself, also in need of significant repairs and rethinking. Since the plants require secure housing in the open air from spring through fall, we needed to schedule the pavilion work for winter. We expedited obtaining construction materials, lined up contractors, and kept our fingers crossed that late season snow would not slow our momentum. Once the bonsai were placed in their cold storage facility for overwintering in mid-November, we set to work.

A small loader was used to bring the heaviest specimens from cold storage to the pavilion in April 2022. Here Greenhouse Horticulturist Chis Copeland maneuvers a Hinoki cypress into place with guidance from Plant Propagator Sean Halloran (left) and Bonsai Specialist Jun Imabayashi (hidden).

Our first order of business was deciding on improved cedar platforms for the plants. After measuring the dimensions of each container, we determined that 10 platform sizes would accommodate all the diverse specimen sizes in the collection. Separately, we contracted a rebuild of the center pavilion table, which is useful for the display of smaller specimens, and replaced a roof beam and the façade of the structure’s center post. For the pedestals, we selected understated and sturdy corton steel I-beams, which are rust resistant and will develop a patina over time. Ten pedestals were cut from the last beam of corten steel available in Massachusetts―the stars were aligned!

When the weather was finally conducive to installation in early April, both plants and pavilion were ready. Jun led efforts to move fifteen bonsai specimens into the pavilion from cold storage on April 18th, and they were unveiled to the public on the very next day. We were overjoyed to meet our demanding deadline, but we weren’t done yet.

View of plants on display in the newly renovated bonsai pavilion. Tiffany Enzenbacher

One of our newest acquisitions, an exquisite 30-year-old Austrian pine (Pinus nigra) forest styled and donated by benefactor Martin Klein, required its own display. We hand-picked granite blocks and had a special-sized platform built to accommodate the pine forest in the space outside the pavilion. ‘Sensei’, the name Mr. Klein gave this striking specimen to honor bonsai artist John Yoshio Naka (1914-2004), was presented for public viewing the week preceding our busiest day of the year―Lilac Sunday. Display enhancements were finally completed in July, when native perennials were planted adjacent to the pavilion.

An exquisite 30-year-old Austrian pine (Pinus nigra) forest styled and donated by Martin Klein, on display outside the pavilion amid newly planted perennials. Tiffany Enzenbacher

After a two-year hiatus, we are thrilled that the oldest collection of bonsai in North America has an updated exhibit just in time for the Arboretum’s sesquicentennial. Like Jun, each of us on the Arboretum’s plant production staff also feel “the history and responsibility to the Arboretum and Larz Anderson” when tending to the plants. Most of all, we’re excited to finally share these extraordinary plants, their history, and our own our knowledge about them with visitors in a much-improved space.