“Explore what’s blooming now,” exclaims a banner above New England Botanical Garden at Tower Hillhis website. And, indeed, there is much to see.
The dramatic property in Boylston, Massachusetts includes two conservatories and 18 separate gardens, both formal and naturalistic. The grounds offer spectacular views of the massive Wachusett Reservoir, as well as hiking trails that enter wilder parts of the nearly 200-acre garden.
As director of horticulture, Mark Richardson is always attuned to the exhibition calendar his team provides to delight more than 225,000 visitors a year. But the garden has two additional exciting botanical projects—the planting of blight-resistant American chestnuts and the restoration of a historic apple collection lost to disease—that are not seen in the same way. At least, not yet.
These works go comparatively unnoticed next to the rainbow border in the Garden of Inspiration area, orchestrated to bloom throughout the season in an evolution of hues, or on the living walls of colorful textured plants in an area called the Court.
But chestnuts and apples look set to make a comeback – if undervalued for now – with major festive moments on the way. Those who work with plants often need to take the long view.
Sometimes the view is too big, Mr. Richardson knows — with chestnuts, especially.
“When you run a botanical garden, you hope it’s going to be here in perpetuity,” he said, and you work with that horizon in mind, not just this year’s displays. “You expect this property, this garden to survive long after whoever is actively managing it.”
Both chestnut and apple trees have an important history on this piece of land, which, in 1986, became the home of the Worcester County Horticultural Society, one of the oldest horticultural organizations in the nation. Apples honor the society’s long agricultural heritage. chestnuts incorporate a goal outlined in the botanic garden’s 2020 strategic plan, calling for the land to be used for conservation research.
The apple collection, which includes heirloom varieties as old as the 16th century, once greeted visitors as they drove up the winding road. Every fall, at harvest time, the trees were the focus of a popular apple festival.
This was not the first house in the collection. It was started by a former Depression-era horticultural society trustee and then lived for a time in nearby Old Sturbridge Village before becoming part of the botanic garden.
But the latest incarnation of the orchard had to be cut down in November 2019 due to fire blight, a disease caused by a naturally occurring bacterium that was once again manageable in the Northeast, and more of a summer issue.
“It’s really a climate change story,” Mr Richardson said, because more frequent warm and wet spring weather has sparked outbreaks of the bacterium that could no longer be kept under control.
Where chestnuts once dominated
Long before it was a botanical garden with an orchard, the property had wooded areas that were rich with American chestnuts (Castanea dentata). It was the dominant canopy tree there until the early 20th century, when chestnut blight, a fungal pathogen accidentally introduced to trees from Asia, moved in.
Various estimates put the death toll in the first half of the 20th century at between 3.5 and 4 billion trees — or at least their above-ground parts. Roots may survive.
At the naturalistic edges of the botanic garden landscape, some root systems that have survived send up stump shoots, Mr Richardson said. Among the hardiest of these, a tree can reach 25 feet and live 15 or 20 years before it, too, succumbs.
“The scourge is still here. the chestnuts are still here,” he said. “We know the conditions are ideal for the chestnut. This is exactly the environment in which they grew up.”
Last fall, in partnership with a Virginia-based nonprofit, American Chestnut Cooperators’ Foundationthe botanic garden became a long-term research site, joining the foundation in its effort to reintroduce the chestnut tree to the eastern forests.
Unlike the approaches of other research organizations—including hybrid crosses of American and Chinese chestnuts and a transgenic line of trees made by inserting a gene from wheat into the chestnut’s DNA—the foundation’s approach is entirely American. Since 1999, he has used genetics from large, upright American chestnuts from various locations that display natural blight resistance to make increasingly resistant crosses.
About two dozen of the resulting saplings were planted at the New England Botanical Garden last October. This spring, 160 nuts went into the ground. Each is carefully marked and recorded and protected from predation by animals.
Propagation 268 Replacement of Apples
Restoration of an apple orchard involves a more defined schedule and protocol.
The botanic garden has had an apple tree replacement plan since about 2010 because the orchard’s trees had been grafted onto seminal rootstock with a lifespan of only about 30 years and the end was fast approaching. Mr Richardson’s predecessor planned to start replacing perhaps 20 per cent of the trees each year until the orchard was rejuvenated and ready for another 30 years.
“Unfortunately, the fire came and interrupted that plan,” Mr Richardson said, setting in motion a triage effort.
When he joined the garden in autumn 2018, from a similar position at the Native Plant Trust, one of his first tasks was to call on John Bunker, an heirloom apple specialist. They took a look around, so that Mr. Bunker, who founded Fedco Trees in Maine in 1984, could make an assessment.
Mr Richardson remembers the moment the diagnosis was made. “I want to help you restore the apple orchard,” Mr. Bunker told him. “But it means you’ll have to cut down all the trees.”
A few months after this heartbreaking verdict, in late winter, Mr. Bunker collected about 10 pieces of wood from the plant from each of the surviving trees in the collection. He brought them back to Maine to use to propagate the botanic garden’s next-generation orchard, which would be planted in 2021.
The goal was 268 trees in total: two of each variety, one grafted onto each of two different semi-dwarf rootstocks, as well as a selection of 30 trees grafted onto standard rootstock, which would grow and live longer – 100 years about — framing key parts of the road to once again offer a proper welcome.
Semi-dwarf rootstock, the norm in commercial orchards, allows for closer spacing and easier management, including pruning. In semi-dwarf soil, trees may grow to 20 or 25 feet tall. those with normal rootstock would be closer to 40. In addition to determining mature size, “the rootstock imparts certain characteristics to the resulting tree,” Mr. Richardson said, including disease and drought resistance.
Each variety of apple combined with a specific rootstock grows at a slightly different rate. At the moment, “when you look at the orchard, it’s very irregular,” Mr Richardson said, “and that’s just the nature of the beast.”
He looks forward to seeing the fruit appear in another few years and eventually restarting the botanic garden’s barkwood distribution program – providing branches for grafting – so that the collection’s living genetics can enter gardens and orchards elsewhere. This program, which was halted by the fire, was an important aspect of the orchard apple conservation effort and had sent up to 1,500 cuttings annually to a total of 26 countries.
Preserving valuable germplasm like these apple varieties is not done by stockpiling. “It really helps to have multiple locations for trees,” Mr Richardson said. “Trees die for many different reasons: they get hit by a car, someone forgets to water them and they don’t make it through the summer, a lightning strike — anything like that can happen. The more reps you have, the better.”
Because apple trees are not grown from seed but propagated clonally, each one resulting from a cutting is genetically identical. This means that “an heirloom apple variety today tastes identical to the one it did 500 years ago,” Mr Richardson said.
Which one are you most looking forward to trying?
It’s hard to say. All the trees had to go so that he could taste their fruit. His colleague Dawn Davies, who manages the formal gardens, has told him about the various standouts, including the Opalescent, her favorite apple, with its ultra-glossy, sugary skin and juicy interior, and the Wolf River, the largest fruit. of all, at more than a pound each. (Fedco Trees offers these and many other heirlooms from the collection.)
As for chestnuts, they won’t be available for holiday stuffing – or to support woodland animals like squirrels, turkeys, deer and bear – any time soon. But the staff members and their successors will be watching, carefully recording every event in the course of the chestnuts.
“Hopefully we can watch these over the next 25, 50, 100 years and see how successful they are. We know some of them will succumb to the blight, but we know some of them will survive and be able to produce nuts that will result in new trees,” Mr Richardson said.
“It’s exciting,” he added, “to be able to support this project.”
Margaret Roach is the creator of the website and podcast A way to gardenand a book of the same name.
If you have a question about gardening, email it to Margaret Roach at gardenqanda@nytimes.com and she can answer it in a future column.
