more rooftop farming, s’il vous plaît

French postal workers atop their office building || photo by Charles Platiau, Reuters

Through innovative policy and dedication, Paris has kickstarted a rooftop revolution that’s improving Parisians’ work experience, one office building at a time. In January 2016, city legislators and 33 companies pledged to plant 100 hectares (247 acres) of green roofs and walls within the French capital by 2020, a third of which would be devoted to urban agriculture. Since formalizing this goal through the Objectif 100 Hectares (Target 100 Hectares) charter, Parisians have busily mobilized across the city’s skyline. Last month, Mayor Anne Hidalgo announced the first wave of projects – 32 sites in total – that aim to produce “425 tonnes of fruits and vegetables, 24 tonnes of mushrooms, 30,000 flowers… 8,000 litres of beer and 95 kilograms of honey,” according to a Reuters report.

Taking care of business || photo by Sarah Langinieux, Cityside

Among these projects, a 900 square meter (0.22 acre) rooftop farm atop a French Post Office building in northern Paris began production on September 14, 2017. A group called Facteur Graine (Seed Postman) manages the farm, which is accessible to the approximately 500 postal employees below. The farm gives employees the opportunity to step away from their digital day jobs into the fresh air, amid ripening fruits and vegetables, and chickens! Employees may soon also see medicinal plants, aromatic plants, and bees within their the rooftop farm.

In addition to benefiting the environment (through rainwater management, carbon sequestration, pollinator habitat provision, etc.), Paris’ rooftop farms could also improve employee happiness, which in tern benefits an employer’s bottom line. Studies indicate that views of nature and access to fresh air at the workplace directly impact physical health and well-being, thereby decreasing absenteeism and increasing employee efficiency and retention.¹ Exposure to these elements – which can be achieved at a rooftop farm – can lower blood pressure, improve stress recovery rates, enhance mental stamina and focus, improve cognitive functions, increase learning rates, and elevate mood, as demonstrated by case studies from the past 25 years.²

So rather than “going postal” at your desk, maybe you can convince your employer that the best decision for your happiness and their bottom line involves farming your office’s rooftop.


¹ Terrapin Bright Green LLC (2012)

² Terrapin Bright Green LLC (2012)

Whole Bazaar rooftop book sale

Roof-to-Table Launch Event Philadelphia || photo by Jane Winkel

Roof-to-Table Launch Event Chicago || photos by Paula Mandel

Despite this year’s erratic weather, spring has officially sprung!  For gardeners and aspiring DIYers alike, this could mean that you’ve been quietly plotting your early season veggie planting, or maybe you’ve been dreaming of a brand new garden.

If you’re planning to grow this year’s edibles on a roof, balcony, or fire escape, you’ll likely have more than a few questions.  Luckily, “EAT UP | the inside scoop on rooftop agriculture” (New Society Publishers, 2013) is here to help!  As the first full-length book about rooftop food production, EAT UP delivers the answers you’ll need.

You can buy this carbon-neutral guide as a book or e-book through all the regular sellers (Amazon, Barnes & Noble, etc.).  But if you’re in Philadelphia on April 8th, hang tight on that purchase!  Come meet EAT UP author Lauren Mandel, PLA, ASLA on the roof of Whole Foods Market South Street and buy a fresh copy in person.  You’ll have the chance to chat about your own rooftop garden, buy roof-to-table notecards and postcards, and can even get your book signed, if you’re so inclined.

We’ll see you on April 8th at the market’s Whole Bazaar event, rain or shine!

data we can eat


McCormick Place Rooftop Farm test plots || photo by Lauren Mandel

Edible crops are dappling our cities’ skylines in growing numbers, and yet, the blossoming North American rooftop agriculture movement remains in its infancy.  As rooftop farmers and gardeners increasingly build knowledge by experimenting and improvising with things like crop selection, staking techniques, and soil amendments, is there room at the table for formal scientific inquiry?

24_The Ledge_byPRogers

Rooftop fennel || photo by Patrick Rogers Photography

In celebration of my one-year anniversary as a landscape performance researcher (and licensed landscape architect!) with the Philadelphia-based landscape architecture and ecological planning firm Andropogon, it seems appropriate to give a nod to research.  Entering this world of site performance analysis has heightened my awareness of the need for field research, or in this case “roof research” (pun intended), to cultivate useful information for rooftop agriculture stakeholders, from growers to restauranteurs to entrepreneurs.

At its core, scientific inquiry allows us to better understand our world through developing questions and then proposing evidence-based explanations.  This process may allow us to notice trends, such as tomato plants producing more fruit on rooftops than at-grade, or even formulate cause and effect theories, like increased soil drainage causes increased tomato fruit production.  Building a body of scientific research around rooftop agriculture is essential in maximizing the legitimacy of our young movement and the quality/efficiency of production.  While publications exist about the benefits of rooftop agriculture and opportunities for industry-wide growth, surprisingly few studies have been published that address the technical “how to” of rooftop farming or vegetable gardening.

One notable rooftop farm engaged in an experimental study in 2013.  The McCormick Place Rooftop Farm launched a “thin farming” research effort to determine the optimal soil amendment regiment for a smattering of rooftop crops grown in full sun and partial shade.  The study, conducted by the Chicago Botanic Garden’s urban agriculture education and jobs-training initiative, Windy City Harvest, involved 20 test plots that composed the then, 1/4-acre farm, with systematic additions of 0%, 30%, 50%, or 70% amendments (by volume) in the planting hole of each veggie start.  Daily observational data fed into a study and informed the subsequent year’s crop management strategy.  Since that time, the farm has expanded to 2.5-acres – the Midwest’s largest rooftop farm – and produces 8,000 lbs. of produce annually for use by the McCormick Place convention center in the building below.

How can you engage in scientific inquiry within your rooftop farm or veggie garden?  Here are six easy steps to follow:

1| Research question: Develop a question that can be answered through the collection of quantifiable data, such as pounds of fruit, height of plants, frequency of irrigation, or number of maintenance visits.  This question may be causal in nature: How does soil drainage affect tomato yields?

2| Literature review: Perform a survey of published literature to better understand what questions others have asked, how they’ve investigated those questions, and what findings they reached.  Like most non-academics, I don’t have access to expensive journal databases, like EBSCOhost, so I usually begin surveying the literature through Google Scholar.  When I find relevant publications, I add them to a running list of references using the Purdue Owl Writing Lab‘s user friendly APA formatting rules.

3| Hypothesis: Based on your literature review, develop an educated guess about what will happen in your experiment: If soil drainage increases, then tomato yields will increase.  Also acknowledge the opposite, or null hypothesis, which you will later accept or reject: If soil drainage increases, then tomato yields will not increase.

4| Experimental design: Next, plan an experiment in which you can change one condition, or variable, at a time (such as degree of soil drainage) while keeping all other conditions constant.  This is how you isolate the variable you’re examining to support causal findings.  You’ll need a comparison that shares the constant conditions, which will serve as the experimental control.  Be sure that your sample size (such as number of tomato plants) is large enough to reach statistically significant findings, which can become even more significant it the study is replicated.

5| Data collection + analysis: Now you’re ready to carry out the investigation that you designed.  Set a schedule for collecting data then make sure that the data is obtained the same way, ideally by the same person, each time.  After the experiment is complete, thoughtfully analyze the data to draw relationships between evidence and explanations.

6| Communication: Sharing what you learned is the most critical step of the scientific process, assuming you aim to advance the rooftop agriculture industry’s knowledge base!  Scientific communication traditionally involves publishing a paper in a scientific journal or presenting your results at a conference during a talk or on a poster.  As a practitioner-researcher, I additionally find great value in writing about studies in trade magazines and blogs, and speaking about them at all sorts of conferences and events.  These outlets generally reach audiences beyond the scientific community, and in the case of rooftop agriculture, the practitioners may be your target.

more bees please


Rooftop beehive in north Philadelphia || photo by Lauren Mandel

Standing on the roof of SHARE Food Program in north Philadelphia, the audible hum of bee wing vibration is hypnotizing.  Workers dart out of their hives to forage for pollen and nectar, others sluggishly return with caked pollen baskets, and those within the stacked wooden boxes flap incessantly to cool the hives for their queen.  Up on a roof these canopy dwellers are right at home, and with so much activity buzzing around the hives, it’s hard to believe these bees, like their brethren throughout the country, have a slim chance of survival.

Since its importation to the U.S. in the mid-1600s, the European honey bee (Apis mellifera) has unequivocally shaped our food system, contributing more than $19.2 billion to the value of crop production within the U.S., according to a 2010 study by Cornell University researchers. While most agricultural crops are visited by a variety of pollinator insects, the American Beekeeping Federation notes that certain crops, like blueberries and cherries, are 90% dependent upon honey bees for pollination. Almonds possess the unique quality of being entirely dependent, requiring an annual importation of 1 million colonies, or 41% of all U.S. managed honey bee colonies, just to satisfy California’s crop.


Native Hunt’s bumble bee (Bombus huntii) visiting a sunflower || photo by Clay Bolt

Tragically (particularly for almond lovers), in 2006 the U.S. honey bee population began plummeting due to Colony Collapse Disorder (CCD), a syndrome resulting in the exodus and death of drones from the hive, leaving the queen and immature bees marooned, to perish. The definitive cause of CCD  has yet to be scientifically determined, but speculations include parasites, pathogens, pests, poor nutrition, sublethal exposure to pesticides, climate change, and low genetic diversity, or some combination thereof.  What a buzz kill.

But there’s hope!  Enter North America’s 4,000+ native bee species.  Do these insects have what it takes to pollinate our farm fields, yards, stoops, window boxes, and edible skylines? “According to scientists, natives are more than up to the task of filling in for beleaguered honey bees,” writes National Wildlife senior editor Laura Tangley in her provocative article, “Being there for the bees.”  This diverse, rarely-studied group of insects co-evolved with many of North America’s native flowering plants and are therefore critical to our ecosystems and food supply.  “In the United States alone, native bees contribute at least $3 billion a year to the farm economy,” says Mace Vaughan, an expert quoted in Tangley’s article.  Native bees are solely responsible for pollinating crops such as tomatoes and eggplant, and much more efficient than honey bees at pollinating many native crops, like pumpkins, watermelons, blueberries, and cranberries.


Diverse native bee varieties || image by Clay Bolt

Taxonomically, all bees belong to the sub-order Anthophila and one of six families:  Andrenidae (mining bees), Apidae (cuckoo, carpenter, digger, bumble, honey bees), Colletidae (plasterer bees, masked or yellow-faced bees), Halictidae (sweat bees), Megachilidae (leaf-cutter bees, mason bees, allies), and Melittidae (melittid bees).  Unlike the honey bee, most native North American bees are relatively solitary in nature; nest underground, in hollow stems, or in dead wood; and don’t make honey.  Their biggest threats to survival include disease, habitat loss, pesticide exposure, climate change, and most recently, insecticide spraying intended to target Zika-carrying mosquitoes.  Despite these pressures, it’s conceivable that native bees’ incredible genetic diversity provides an advantage over the honey bee in resisting CCD.  With more research, increased education about the habits and importance of native bees, and a ban on insecticide spraying, pollinator populations will hopefully stabilize.

Here’s how your rooftop farm or vegetable garden can help native bees and our food system:

  • Provide nesting sites | Build or buy in a native bee nest (they’re beautiful!) for installation in your farm or garden, or on a nearby roof area.  If you see ground-nesting native bees in your media, try to stay out of their way so they can do their job.
  • Plant native flowering plants | Make sure a variety of native plants on your roof are booming from early spring through late fall to provide native bees with a variety of pollen and nectar sources.  Long-blooming herbs offer a great supplement to vegetable plants.
  • Offer a water source | Bees get thirsty!  Make sure to provide a rooftop watering source so your pollinators don’t wonder off.
  • Eliminate chemical use | Keep your rooftop farm or garden chemical free by avoiding synthetic insecticides, herbicides, fungicides, and fertilizers.
  • Tell your friends | Don’t be shy about proselytizing what you’ve learned about supporting native bees!  Make sure prospective growers know that your farm or garden is the bees knees.

chocolate skyline

Cacao “beans” drying on a rooftop in Ghana || photo by Toby Webb

This Valentine’s Day season I’d like to be as close to chocolate as possible, and consumer market trends suggest that I’m not alone.  For those of us living far from the equator, though, the main ingredient in chocolate, cacao, travels an incredible distance to reach our plates.  Cacao are seeds, often referred to as “beans,” found within football-shaped pods that grow from the trunk and branches of the cacao tree (Theobroma cacao).  The tree is native to the South American lowlands and is now propagated within rainforests throughout the equatorial tropics and sub-tropics of Central America and parts of South America, Africa, and Asia.


Agricultural rooftop use in Granada (top) + Mexican farmers drying cacao out of their chickens’ reach (bottom) || photos by The Grenada Chocolate CompanyMadre Chocolate/David Elliott

The process of deriving coco from the cacao bean is labor-intensive and is often performed by growers and plantation owners in remote areas.  Once cacao pods ripen, they’re cut from the tree and the beans are extracted.  The beans are fermented, laid on a flat surface to dry, and then generally exported to another country where they are roasted.  The roasted beans are ground to a fine powder called cocoa, which is then blended with sugar and other ingredients to produce the creamy sweetness that we’ve grown to love.

“Cacao seeds, or ‘beans,’ have to be dried after fermentation as a measure to prevent molds [and] mildews from growing on them during transport,” explains botanical scientist and cacao expert Dr. Cindy Skema.  “It is a bit of an art, though, because the beans must not be over-dried because they can become too brittle and that creates problems in processing.”  As you may imagine, naturally flat areas for drying cacao beans are a rarity for many rainforest inhabitants.  Some growers and plantation owners build structures specifically designed to dry the beans, with protective covers that are either static or slide on tracks, like a convertible roof, to protect the crop from incoming rain storms and shield the beans from insects and birds.  Others lay beans on their village’s concrete, central square, as I’ve seen myself in rural Venezuela.

In isolated instances around the world growers have been seen industriously using their rooftops as drying grounds for cacao beans.  Multiple examples exist in Trinidad, but growers and plantation owners in Brazil, Ghana, the Dominican Republic, Grenada (in the Caribbean), Vanuatu (in the South Pacific), and Mexico have also pursued the practice.  In Oaxaca, Mexico, chocolatier consultant and author Clay Gordon visited a family farm that allocated roof areas to drying cacao because this location was, “out of the reach of chickens,” he says.  Gordon explains, though, that drying cacao on roofs is not a common practice due primarily to, “the labor of getting the beans up there in the first place. Furthermore, not all roofs [in cacao-growing locations] are flat or sturdy – many of them are pitched and made of galvanized corrugated metal, which is not a good surface for drying beans.”


Cacao drying on rooftops in Vanuatu (top) + Trinidad (bottom) || photos by Zaia Kendall + Leonie Milner

Skema agrees that drying cacao on rooftops is not very common, but to her, the practice comes as no surprise.  “It makes sense,” she says, “I mean [the roof] is a typically open, available space that gets very hot and is a bit cleaner than ground level, or at least without people [or] animals walking through.”  Skema notes that around the world roofs are used to dry a variety of things, like edible plant material, meat, and clothes.

Agriculture involves not just food production, but also processing, or the preparation of crops for sale via washing, fermenting, drying, etc.  Rooftop agriculture generally evokes images of crops strictly in production, even for me, and we rarely stop to think about supplementary agricultural practices fit for rooftops.  Using roofs to dry cacao is a beautiful example of the creativity of farmers who, in all reaches of the world, have independently developed the same practice.

This Valentine’s Day, when you’re craving chocolate, pause to think about whether your indulgence spent part of its lifetime on a roof, under the sun, and what other non-production agricultural practices could occupy our rooftops.


Bletter, Nat. Email correspondance. 17 November 2015.

Gordon, Clay. Email correspondence. 18 November 2015.

Gordon, Clay. “Madre Chocolate-From The Road In Xoconusco, Chiapas.” Discover Chocolate, 7 March 2011. Web. 11 October 2015.

Skema, Cynthia. Email correspondance. 10 November 2015.

Skema, Cynthia. “Ka-Pow Cacao.” Morris Arboretum of the University of Pennsylvania. 100 E Northwestern Ave, Philadelphia, PA 19118.  Lecture.

food city scenario


Excerpt from “Fayetteville 2030: Food City Scenario” || Image by the University of Arkansas Community Design Center

What would your city look like if urban agriculture drove development? The University of Arkansas Community Design Center posed this question in 2012 when a team of designers, scientists, lawyers, and students explored what their rapidly densifying city of Fayetteville, AR would look like by 2030, the point at which the population is projected to double to approximately 140,000 residents.  The team, led by Community Design Center director Stephen Loni, used scenario planning – a speculative process that anticipates how specific decisions will shape long-term realities – to develop “Fayetteville 2030: Food City Scenario,” or Food City, as it’s better known.  This visually enticing project depicts a future Fayetteville that prioritizes food security and food localization as organizing elements of urban growth.  Food City has earned national recognition by winning multiple awards, including an ASLA 2015 Professional Honor Award, and appearing as the subject of a feature article in Landscape Architecture Magazine‘s January 2016 issue, written by EAT UP author Lauren Mandel.


Tri Cycle Farms and permaculture farmer Don Bennett || photo by Lauren Mandel

“When you’re trying farm farmers and grow growers, it’s all about accessibility,” says Fayetteville urban farmer Don Bennett, who founded Tri Cycle Farms in 2011.  Don and his flock of volunteers, many of whom are food insecure, cultivate nearly 2-acres of land in the city’s geographic center using permaculture techniques.  Don is part of a growing food localization movement in Fayetteville that focuses in large part on food equity and access.  Other local, budding establishments that help bring fresh, nutritious food to Fayetteville’s residents include Feed Fayetteville (a food security non-profit), Apple Seeds Teaching Farm (a hands-on agricultural education site), The Farmer’s Table Cafe (a popular farm-to-table restaurant) and the Fayetteville Farmers’ Market (which was established in 1973 and is now the largest producer and vendor market in Arkansas).


Excerpt from “Fayetteville 2030: Food City Scenario” || Image by the University of Arkansas Community Design Center


Excerpt from “Fayetteville 2030: Food City Scenario” || image by the University of Arkansas Community Design Center

Do you want to learn what’s on-tap for Fayetteville’s transforming food system and read more about the people behind the movement? Check out “The Next Meal” in Landscape Architecture Magazine‘s digital January 2016 issue or pick up the print edition at your local Barnes & Noble store before mid-February.

top 10 reasons to buy EAT UP this holiday season

Not sure what to give your hip, garden-loving, urban foodie this holiday season?  How about a carbon neutral gift that they’ll use to gain inspiration and change the world?  “EAT UP | the inside scoop on rooftop agriculture” makes the perfect gift or stocking-stuffer for your mom/dad/aunt/uncle/cousin/daughter/son/friend/neighbor, or even that cute guy down the street.  Through case studies, checklists, and interviews with rooftop agriculture’s industry leaders, this book inspires readers to garden their own rooftop and farm the skyline.  Don’t fret, EAT UP‘s available through Amazon Prime and as an e-book.

In case you need some extra convincing, here are the top 10 reasons to buy EAT UP this holiday season:


major league crops

Fenway Farms, atop Fenway Park’s Front Office || photo by Dr. Richard Mandel

The Kansas City Royals may have won this year’s World Series, but the Boston Red Sox were the real 2015 winners.  While this American League team’s game may not have been up to snuff, it’s historic stadium knocked one out of the park in April when Fenway Park representatives announced their plans to build a rooftop farm, the first in major league baseball.  Later that month Fenway Farms materialized, with its first harvest in May.  Now the weather is halting production for the year, which offers the facility’s designers and farmers time to reflect on the farm’s inaugural growing season.


Farm in October 2015 || photo by Dr. Richard Mandel

“All the stars aligned to make this project go forward, but it was ultimately Linda Henry, married to the owner of the Red Sox, who breathed life into it,” says Mark Winterer, the farm’s designer and co-owner of Recover Green Roofs, LLC in Somerville, MA.  “One-year prior to Linda’s involvement, The Red Sox contacted Recover and was interested in a Sedum green roof.  While we couldn’t find the financing to build the Sedum green roof, we were able to find the right [roof area that could support the load of a farm], so when Linda got involved, we were ready to go,” says Winterer.  Fenway Farms is located atop the stadium’s Front Office, on the third base side at the EMC Club Level.  It’s visible from both the EMC Club and State Street Pavilion Levels, but accessible to the public only during stadium tours.  Stop & Shop, Dole, Sage Fruit and Aramark financed the project.

The approximately 4,000 pounds of vegetables and herbs grown at Fenway Farms annually make their way into dishes prepared in the stadium’s EMC Club kitchen.  The stadium’s chefs, including Fenway Park executive chef Ron Abell, choose which crops will be grown each season from a master list, which are then planted in spring and summer by Green City Growers, an urban farming company that serves eastern Massachusetts.

Cucumbers did really well,” says Green City Growers CEO and founder, Jessie Banhazl, “we harvested 600 pounds of cucumbers [during the 2015] season.  Kale, lettuce, carrots, peppers, and eggplants also did well this year.” Banhazl was surprised by a unexpectedly vigorous strawberry crop, so much so that she’s amending next year’s crop plan to include more berries and fruit for Fenway Park’s pastry kitchen.


R.A.M.M. installation at Fenway Farms || photo by Mark Winterer

The farm system itself, designed and installed by Recover Green Roofs, consists of rows of modular plastic crate growing systems lined with filter fabric sleeves – called “Recover Aerated Media Modules (R.A.M.M.) – filled with 10-inches of Vermont Compost custom blended organic soil, with a Weathermatic Smartlink drip irrigation system.  The planter design closely resembles that at Higher Ground Farm, atop the Boston Design Center, designed and built by Recover Green Roofs in 2013.  “Fenway asked if we could do something similar to Higher Ground Farms,” says Winterer, “they liked the idea that it was a relatively inexpensive option, and that they could remove it if need be.”

What changes did the Fenway design include as a result of what Recover Green Roofs learned from the earlier project?  “We learned to buy prefabricated fabric liners because Higher Ground Farms found it difficult to hand make those liners using filter fabric,” recounts Winterer, “we also used individual drip emitters [within each] milk crate instead of using your typical drip line with emitters spaced 12-inches on center.”


“Beta R.A.M.M.” at Higher Ground Farm || photo by Lauren Mandel

One of the most unique qualities shared by both projects is their use of potting soil instead of the modified, lightweight green roof media that’s typically deployed in rooftop farms.  Winterer explains that, “the big take-away from Higher Ground Farm is that the milk crate allowed them to use potting soil up on a roof without worrying about it blowing away.  Vegetable plants are much happier in potting soil than engineered growing media.”  While the plants may be happy, modified green roof media is generally preferred for rooftop farms because it remains structurally stable (without breaking down or compacting) while maintaining its drainage capacity.  By contrast, potting soil decomposes, compacts, and can easily clog filter fabrics within a single season.  These properties suggest that soil replacement may be a necessary component of the Fenway Farms maintenance plan, which may be worth the hassle given the plants’ high productivity in this optimal soil environment.

What changes would the chefs like to see next year? Fewer radishes! “Radishes also did really well, which the kitchen was not happy about,” says Banhazl, jokingly, “we’ll have to pair back on how many we plant this year, they were rolling their eyes at us by the end of the spring every time we walked in with more radishes.”