Less sunshine, more shadows? What taller skyscrapers could mean for Boston Public Garden after zoning change

The new zoning changes recently approved for downtown — paving the way for taller skyscrapers — could have detrimental effects on the venerated cherry blossoms, weeping willows and tulips of Boston’s Public Garden, advocates say.

The country’s first botanical garden — established in 1837 — is likely to see less sunlight as a result of the code revision, according to Leslie Adam, board chair of the advocacy group Friends of the Public Garden.

Adam, who opposed the zoning overhaul in front of the Boston Zoning Commission this week, argued the state’s “shadow laws” — put in place more than 35 years ago as “essential protections for two of Boston’s most iconic parks,” the Public Garden and Boston Common — are not adequate as written to prevent damage caused by new, taller shadows.

Special exemptions allowed for the then-Midtown Cultural District under the decades-old shadow laws will immediately be applied to even taller buildings — 500 feet or higher — without any adjustments 35 years later, according to Adam.

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Shadow laws are regulations that limit the amount of new shadows that new buildings can cast upon the Boston Common and Public Garden, and at what times.

Adam said this week’s changes will mean “hours of new shadows” across both the Public Garden and Boston Common every day.

Sunlight is “essential” for the health of the two landmark urban green spaces and the people who frequent them, she said.

Meanwhile, Boston planning staff contend any new development will go through an already-mandated breakdown process that includes shadow analysis.

“We are committed to enforcing the state shadow law to protect the Common and Public Garden,” said Kairos Shen, chief of planning for the city of Boston. “Second, any development proposal to be processed under the new zoning will go through the Article 80 development breakdown process, where there will be in-depth community engagement to assess and mitigate the potential impacts of that specific proposal, including any impacts that would impact historic aspects as well as the open spaces.”

More than 80 species of plants are cultivated by Boston Parks and Recreation for plantings at the famed Public Garden each year, and more than 1,700 mature trees call the space home, including magnolias, horse chestnuts, dawn redwoods and ginkgo trees.

During peak tulip season this year, more than 31,000 flowers bloomed — a tradition that started in 1846.

What are the zoning changes?

The changes, unanimously approved Wednesday by the Boston Zoning Commission, are part of Boston’s PLAN: Downtown initiative, a larger overhaul of the convoluted zoning code.

The zoning changes for downtown, stretching from Boston Common to the Rose Kennedy Greenway, will allow developers to construct new buildings up to 700 feet tall, or about 70 stories, in some areas. Closer to the Common, heights will be capped at 100 to 155 feet.

Michael Nichols, the Zoning Commission chair who recused himself from the final vote because of his work with a downtown business advocacy group, recently told Boston Magazine there are only “four to six” spots where a new 700-foot tower could be built.

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During Wednesday’s meeting, representatives from the city’s Planning Department clarified that the only new area where a 700-foot height is possible is north of State Street, which they said is far enough from the Public Garden and Boston Common not to cast shadows on them.

Currently, the tallest building in downtown is Winthrop Center at 691 feet and 52 stories tall, which was completed last year. The next-tallest is the Millennium Tower, at 684 feet and 60 stories; and the South Station tower reaches 677 feet and 51 stories.

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The city has said the changes will allow for greater housing density — creating more homes to address the housing crisis — and more diverse business types such as coffee shops, bakeries, fitness studios and entertainment.

Any residential development will have to set aside 20% of the units created as affordable housing under the existing inclusionary zoning rules.

But the proposal merited significant pushback, particularly from neighborhood associations and historic preservation advocates. Some opponents said the changes represent “the ‘Manhattanization’ of Boston.”

Still, the proposal received widespread support Wednesday from the Boston Zoning Commission with a vote of 10-0 — the last major hurdle to clear before heading to Mayor Michelle Wu for her signature.

At the meeting, business alliances, housing advocacy groups and labor unions argued the revamped zoning is essential to revitalizing a struggling downtown economy and creating more housing.

Opponents, though, queried whether the changes would actually produce affordable housing — and not more luxury condominiums with high cost points.

In a statement following the vote, Wu said, “As post-pandemic challenges impact downtowns across the country, this new zoning will help Boston spur new housing, eliminate zoning hurdles for businesses, support more office-to-residential conversions, and infuse new vitality in this important neighborhood and commercial core.”

Advocacy will continue despite zoning vote

Adam, of the Friends of the Public Garden, emphasized her organization isn’t opposed to the continued growth of downtown. Rather, they wanted shadow impacts to be studied for each building project proposal using updated sunshine modeling — and for the city to only allow the Midtown Cultural District exemptions if projects pass muster, not by right.

“We know through science there are ways to do this. And we always think of the long-term, ensuring the parks are here today but also for the next generations ahead of us,” Adam said Friday in an interview with MassLive. “We believe that talking about excellence means digging deeper,” rather than defaulting to 35-year-old exemptions that don’t account for the new allowable heights.

Shen, Boston’s chief of planning, said any new development will go through the Article 80 breakdown process — the city’s guidelines for reviewing a project’s impacts — which requires a shadow analysis.

Andrew Nahmias, a senior planner with the Boston Planning and Development Agency, said the new zoning is designed to further reinforce shadow regulations by explicitly incorporating them into the code.

Those regulations supersede city zoning, Nahmias said, and can only be changed through state-level action.

The state shadow laws were originally enacted in the late 1980s and early 90s in response to the Park Plaza development.

Adam said there is already precedent for them being overridden, pointing to the Winthrop Square Tower, a contentious building project that started in 2017.

State Rep. Jay Livingstone, D-8th Suffolk, whose district includes both the Public Garden and Boston Common, argued the current shadow laws, as written, can’t “represent a backstop of protection.”

“Both our iconic parks are intertwined with Boston’s identity,” he said. “When Boston is shown on TV, it is very commonly an image of one of these two parks.”

Adam said the Friends of the Public Garden will continue their advocacy work despite Wednesday’s vote. “It’s not been a fun week,” she quipped.

“We cannot just sit back because if we sit back, we potentially lose the legacy and the long-run vision,” Adam said. “We’re safeguarding sunlight and civic life for the future.”

MassLive Reporter Tréa Lavery contributed to this story.