By Julia Lloyd
All images courtesy of author
In 2022, Boston experienced the driest summer in 138 years. At the Rose Kennedy Greenway, the park that I worked at in downtown Boston, there were a number of casualties due to the drought. Despite this, some plants not only survived but appeared entirely unaffected by the lower-than-average rainfall.
The Rose Kennedy Greenway is a 1.5-mile park that runs through the heart of Boston from the North End to Chinatown. The park faces a number of unconventional challenges ranging from the heat island effect, the vibrations from the tunnel it was built over, and pollution. Despite these unique challenges, there are a number of plants that do surprisingly well in this challenging urban ecosystem. Among the unbothered were the grasses. Not the turf grasses, but the Panicums and Schizachyriums.
When it came time to redesign one of the beds that completely failed (due to a crushed conduit which cut off all supplemental irrigation), I thought why not use those plants that don’t rely on irrigation anyway?
There is an interesting overlap between urban ecology and coastal ecology. Many of these plant communities face similar environmental selective pressures. This looked like the perfect opportunity to educate the public on local plant communities, and experiment with intentionally impairing the soil.
The park’s soils are becoming more acidic due to acid rain, and the runoff from road salt has been gradually increasing soil salinity. Additionally, changes and precipitation and rising temperatures due to climate change are causing the soils to become more hydrophobic. But when life gives you lemons, why not trash the soil even more? I wondered if there was a way to make the soil so intolerable, that invasive plant species could be kept at bay while native plants thrived.
Could we make the soil so porous, so acidic, and so saline, that the mugworts and black swallow-worts would eventually surrender organically?
The previously full plot.
The empty plot.
The Planting Plan
The nutrient-poor sandy soils of the Cape and Islands support some of the most biodiverse plant communities in the northeast. These plant communities are also incredibly resilient and increasingly rare. Beach houses, golf courses, rising sea levels, and severe weather threaten these ecosystems. However, backyard conservation and ex situ conservation can play a promising role in the survival of these communities.
The Rose Kennedy Greenway planting was to be inspired by the natural succession from coastline to grassland to open woodland. The coastal part of the garden would feature a small rockery, filled with plants like Solidago sempervirens (seaside goldenrod) and Opuntia humifusa (prickly pear cactus). The grassland would feature plants from the sandplain grassland communities dominated by Schizachyrium scoparium (little bluestem), and the woodland would feature the pine baren’s notorious pitch pines and scrub oaks.
Valerie (Ecological Healthcare Horticulturalist) and Charlie (Greenway Volunteer) unloading sand.
Prepping the Site
Thanks to the Greenway’s volunteer program, we had an amazing amount of support in removing the former plantings, including excavating all the dead Knock Out roses and hydrangeas from the site. The soil was regraded and then amended. We applied sulfur to the site to sink the pH and then added several yards of sand to make the soil more of a loamy sand.
Volunteers and staff planting.
Challenges
The biggest challenge of working in the urban environment is that unexpected things can happen. Two days after our first plant installation, a massive sewer pipe was laid right through the middle of the garden. After frantically calling several public works departments, Boston Water and Sewer quickly moved the live sewer line with minimal damage to the plants.
The sewage pipes.
The second unforeseen challenge was weeds. Specifically, we found that amaranth and purslane thrived in the sandy soil. It took many hours of weeding to try and stay on top of these plants. On the positive side, mugwort and black swallow-wort were much less of a problem.
Andropogon gerardi ‘Black Hawks’ (big bluestem) standing tall.
Comptonia peregrina (sweet fern) also holding it down.
Darrah with the plans.
And lastly, the east side of the bed was only a foot and a half deep, prompting us to change our original plan. All the most xeric plants ended up on that end.
The garden in late summer. Juncus tenuis (path rush), Pinus rigida (pitch pine), and Aronia arbutifolia (red chokeberry) are pictured here.
The sandy open areas will eventually be filled with rocks to imitate New England’s rocky coast. Arctostaphylos uva-ursi (bearberry) frames the rocky outcrops.
The Garden in Fall.
Results
We were fortunate to have abundant rainfall this year. It made it a great year for plantings and definitely helped many plants in this garden to get established. Although we lost a couple of bayberries, everything that we planted survived.
This Garden could not have come into existence without the amazing support that I had at the Greenway. A year ago I proposed this idea, and Tori and Val promptly embraced and supported it. Darrah, our Senior Horticulturist, drew up all the plans, made all the calculations, and turned this crazy idea into a reality.
Sam, Maggie, Nate, Liam, Selby, and all of our wonderful volunteers provided the muscle, asked questions, and gave excellent feedback throughout the entire project. Another huge shout out to Pierson’s Nurseries in Maine, and Van Berkum Nursery in New Hampshire. They provided most of the plants for this project, which adapted exceptionally well to the site.
I am immensely proud of what a passionate crew can achieve together, and I hope this garden serves as a model in the future for projects hoping to increase biodiversity while embracing sustainability in urban horticulture.
In a future that is likely to include climate change-induced drought, it will be important to consider the plants that can tolerate these conditions, rather than relying on plants that only serve ornamental purposes. Aesthetics are always changing in horticulture, but the environments we live in are changing too, and we need to work with these changes. Xeriscaping is very popular in the west due to water stress, but there is no reason it can’t be a common design principle in the east. I don’t think it’s too difficult of an idea to get behind. There is something really beautiful about watching grasses sway in the wind.
About the Author:
Julia Lloyd has been working in horticulture for 8 years primarily in Urban Horticulture. She has a diploma from the New York Botanical Garden’s School of Professional Horticulture and worked at the Rose Kennedy Greenway as the lead horticulturalist.