“lettuce” in – it’s cold out here!

High tunnel veggies || Photo by Lauren Mandel

As your asparagus lies low waiting for spring, it has plenty of time to fantasize about warmer soil.  Jump up to a rooftop, and this fantasy could be closer to reality than your vegetables have ever dreamed.

Buildings emit heat.  Since hot air rises, local building codes specify how much insulation must be installed inside the roof to keep this heat from escaping.  But what if there were a way to let some of this heat enter a rooftop greenhouse?

Some ground-level greenhouses rely upon radiant heating to regulate winter temperatures.  This method involves heating the floor so that hot air can warm the plants and soil.  Perhaps this same principle can be applied to rooftop greenhouses, whereby heat from the building is harnessed and re-used.  With new construction, could municipalities be convinced to allow for thinner insulation below greenhouses?

In my travels, I have yet to see this practice in action.  Do you think that it’s feasible?  Would municipalities allow for such an unusual variance?

that is one hot potato.

To the newbie, designing and building a rooftop farm may seem like a cakewalk.  What’s the big deal?  You just plop a regular farm on top of a building and it’s business as usual, right?  Wrong.  Planning a successful rooftop farm requires careful consideration of siting (where the farm will be located), infrastructure, project goals, and long-term financing.  Coordination with the building’s architect is also crucial, particularly when designing a rooftop farm for a building that has not yet been built.

Proper coordination can avoid one serious rooftop threat that ground-level farmers will never face: reflectivity.  Light that reflects off of surrounding surfaces can scorch spinach and burn brassicas.  Highly reflective glass on neighboring buildings, or even on surrounding levels of the farm’s own building, can devastate crops.

Here are two anecdotes that illustrate the power of reflectivity:

1|  The green roof firm for which I work designed and built a courtyard shade garden for an important Philadelphia client.  The courtyard is surrounded by taller building stories, which are faced with glass so that workers can enjoy the garden view.  The garden’s ferns, heuchera, and other shade plants performed well at first, until strong summer rays reflected off of the windows and fried some of the plants!  What seemed at first to be a shaded haven had become a seasonal hotbox.  The most sensitive plants were replaced with sun-loving species, and next time we will coordinate with the architect to avoid a similar mishap.

2|  In 2010 a Las Vegas hotel found itself in a sticky situation when poolside guests were burned by light reflecting off of the hotel’s glass façade.  For 90 minutes each day, the concave building reflects light that is hot enough to melt plastic and burn hair.  Guests have the ability to seek refuge under patio umbrellas, but replace people with vegetable plants, and you’d have some fried green tomatoes on your hands.

farming in the sunshine state

I Grow My Own Veggies || photo by Lauren Mandel

Despite Florida’s abundant sunshine and rainfall, there is a surprising lack of rooftop agricultural activity throughout the state.  The growing conditions are perfect for food production at any altitude, and yet, most growing is reserved for the ground plain.

The one exception is I Grown My Own Veggies in Sarasota, FL.  This 3,000 sf open-air hydroponic farm rests atop a glass factory in a light manufacturing area of the city.  The farm’s Founder, Vincent Dessberg, began growing food on the roof of his factory in 2009 in an effort to grow food as locally as possible and empower his neighbors to follow suit.  His original concept was to build a restaurant below the farm, with the slogan “Your food travels 15 feet, not 15 miles.”

While the restaurant never materialized, the farm continues to produce an impressive variety of crops, including strawberries, chard, kale, tomatoes, basil, watercress, onions, and several varieties of leaf lettuces.  The hydroponic facility contains over 6,000 plants, which are grown in  stacked Styrofoam containers and drip irrigated from above.  Holes in the bottoms of these lightweight containers allow for water to drain from one pot down to the next, thereby minimizing water loss.

The farm produces three to four crop cycles per year, but according to Dessberg, growing during the summer months is tricky.  Marketing to local restaurants has also been tricky, since most of these businesses rely upon large quantities of a few select crops rather than the large variety that Dessberg has to offer.  Due to these difficulties and others, Dessberg brought on Don Gamin to manage the farm.  Gamin is poised to take over completely within the next few months, and is sure to bring some fresh ideas to the table.

indecent exposure

As a Project Manager for the green roof firm Roofmeadow, I regularly travel around the country to perform construction oversight.  In December I had the good fortune of overseeing construction at a hotel in Lower Manhattan, which sits one block from the Hudson River.  From six stories up the view was unparalleled – and so was the wind.

During construction, the green roofs and raised bed production area experienced 50 mph winds.  A much milder microclimate could be found at the street level, but up on the roof, temperature fluctuations and extreme wind conditions reigned.

Lower Manhattan green roof construction || photo by Lauren Mandel

Exposure is one of the most significant obstacles to rooftop farming.  High winds cause winnowing (soil loss) and desiccation (soil drying), while temperature fluctuations can cause crops to bolt (flower) prematurely.  Each roof experiences a slightly different microclimate, but some basic rules of exposure are as follows:

1| Mind the water: Rivers and other bodies of water in cities often act as wind corridors.  Selecting a roof that is shielded from these channels can help to minimize extreme rooftop winds.

2| Stay low: Higher building stories generally experience greater wind speeds, which means that a farm will experience less stress on top of a 1-3 story building than on a taller structure.

3| Surround yourself: Take advantage of high neighboring buildings and taller segments of the farm’s own building, which can act as wind breaks. Positioning your farm directly south of a taller building wall can help to block gusts.  The wall may also capture heat, which will warm the adjacent soil. Be sure to avoid taller buildings to the south that will cast shadows on your farm.  Also keep in mind that building north of a vacant lot can be risky, because you never know if a taller building will be erected on that site.

4| Cover up: Temperature fluctuations can be minimized by covering your crop rows with shade cloth.  This thin cloth is used regularly on ground-level farms, and it benefits crops by capturing the heat that is released by the plants and soil.  Rooftop wind will fill the cloth like a sail, and so it’s best to build low hoop houses to frame the cloth.  These hoop houses should be screwed or bolted to the sides of raised beds, or ballasted by the walkways between farm rows.

revamp | Eat Up v3.0

A manuscript often takes on several personalities before finding its most publishable persona.  As it turns out, Eat Up is no different.

I wrote the first draft of Eat Up in 2010 while in graduate school, and consequently chose to target an academic audience.  Writing this first draft was exhilarating and empowering, and I felt as though I was on track to contribute something truly meaningful to academia.  Several months after graduating I re-read the draft, only to find that what I had once perceived as well written was actually dry and, well, academic.

After the panic and disappointment subsided, I decided to hunker down and revamp the manuscript.  I hired someone to help with editing and strategic development, and launched full force into Eat Up v2.0 in 2011.  This new and improved version targeted designers, practitioners, policy makers, food activists, and yes – even academia.  The tone became more readable, and the chapter titles, a bit snarky.  V2.0 was a hop in the right direction, but what I really needed was a leap.

Eat Up v3.0 | cover and page 1

In comes Eat Up v3.0.  This draft re-evaluates both the underlying message and the target audience of v2.0.  The most significant change lies in the manuscript’s restructuring: the book will now be split into three smaller volumes.  Each volume in the boxed set will target a distinct audience, thereby providing the reader with the knowledge that he or she seeks, without all the extraneous information.  The books will, of course, reference each other, so that readers will be exposed to the full breadth of rooftop agriculture one snippet at a time.  Working titles for the volumes and their audiences are as follows:

Eat Up |  nourishing yourself with food from the roof  -  This volume will act as a DIY for individuals and groups who are interested in growing vegetables and herbs on their own roofs.  Whether planting a few tomato plants or starting a rooftop community garden, this book will appeal to small-scale growers around the country.

Eat Up |  from beans to bucks with food from the roof  -  This volume will target entrepreneurs, restaurateurs, and others who are interested in the boutique aspect of rooftop agriculture.  The book will introduce labor, marketing, and distribution strategies while providing useful tips for “making it happen.”

Eat Up |  feeding the people with food from the roof  -  The third volume will focus on large-scale initiatives and rooftop agricultural networks.  The content will target city planners, policy makers, designers, and academics who are interested in learning how rooftop agriculture can feed the masses.

What do you think about this overhaul?  Are these changes a step in the right direction?

boutique industry

Many of the pioneer rooftop farms sprinkled throughout the U.S. are much smaller than their rural counterparts.  This scale differential begs the question of production volume.  How can a rooftop farm that is less than an acre feed the masses?  What purpose does a farm fulfill if not to produce as much food as possible?  The truth is that rooftop farms of all sizes provide value not only in their ability to produce food, but also in their propensity to demonstrate what is possible.

Eagle Street Rooftop Farm chili peppers || Photo by Lauren Mandel

We are at the forefront of the rooftop agriculture movement in the U.S., which means that each and every skyline farm has the potential to lead by example, regardless of it’s size.  High altitude farmers like Annie Novak from Brooklyn’s Eagle Street Rooftop Farm have begun sculpting this boutique industry, and the movement is picking up steam.  As the message spreads and rooftop agriculture’s value is more thoroughly understood by the general public, the industry can blossom out of boutique-dom into something more essential.

Simply put, today’s boutique farmers will inspire the architects of tomorrow’s food system.  They are the fuel for change, for progress.

The question then becomes how to spread the message of rooftop agriculture.  How does a rooftop farmer with limited acreage reach as many people as possible?  What is the most efficient way to grow a farm’s brand without physically expanding?  The answer may lie in innovative marketing strategies.  Several rooftop farms are delving into “value added” products.  These are minimally processed goods such as jelly or hot sauce, which can be enjoyed over a prolonged period and may contain the rooftop farm’s brand.

Farm visitors also have the ability to spread the word by telling others about their experience.  You can also talk about what you read, so go ahead and kick-start this revolution.

there’s nothing like a heat island

When travelling from my forested neighborhood to Center City Philadelphia, the change in temperature is often startling.  The commute is only ten miles, and yet the temperature noticeably warms by at least 5° F when approaching the city.  This globally ubiquitous phenomenon, known as the urban heat island effect, occurs when urban development replaces vegetation, soil, and open water with impermeable surfaces such as concrete, asphalt, and dark-colored roofs.

Philadelphia, PA || Image by Google Earth

Environmentalists tend to sneer at the thought of the urban heat island effect, which wreaks havoc on natural ecosystems and contributes to global climate change.  But what if we ReThink this deleterious phenomenon and leverage it to our agricultural advantage?

The warmer the climate, the longer the growing season.  This implies that cities can be used to cultivate fresh food for a slightly longer time span than can rural environments.  Extended growing seasons are particularly relevant in cooler climates, whereas warmer areas (such as California and Florida) can easily grow food outdoors year-round.  Cool-climate farmers often artificially extend the growing season with greenhouses or high tunnels.  These structures can be prohibitively expensive for many novice growers, which means that a naturally-prolonged growing season becomes increasingly attractive.

Of course the ultimate objective from a landscape architectural, urban design, or ecological perspective is to minimize the urban heat island effect altogether.  This is a lofty, yet tangible goal, which will take many years of design and development to reach fruition.  In the meantime, let’s leverage this heat and  grow some food.

a financial giant and a pitchfork

While young metro-agrarian trend setters around the country dive elbow deep into compost, one financial giant wants to get its hands dirty too.  Goldman Sachs, the multinational investment banking and securities firm, is constructing a raised bed production area on the roof of the firm’s newly acquired Embassy Suits Hotel in Lower Manhattan.  The hotel is located in the affluent Battery Park City neighborhood, and will contain a restaurant that aims to incorporate rooftop produce into its menu.

Cedar for raised beds || Photo by Lauren Mandel

The sophisticated rooftop design incorporates swaths of extensive green roof, decorative crushed glass, and rubber pavers in addition to the farm plots.  Ken Smith Landscape Architect designed this layout, and hired Roofmeadow (the green roof firm for which I work) as the project’s green roof consultant.  Roofmeadow maintains a national network of licensed green roof contractors, one of whom, the Sponzilli Landscape Group, is currently installing this project.  I had the good fortune of visiting the site this morning to perform construction oversight, and was able to see the farm plots first hand.

The raised beds themselves are much like those on the ground plain, except that these beds more intricately address the threshold between soil and underlying substrate.  Rooftop raised beds require a well-planned drainage system in order to maintain proper soil moisture in each plot.  A bed that does not drain effectively can become waterlogged and kill the plants growing within.  A bed that drains too quickly will require significant levels of irrigation, and will therefore produce weak plants while wasting water.  The Embassy Suits Hotel raised beds utilize specially engineered growing media that holds a specific amount of water between its particles.  This media sits on top of a sheet drain, which was selected for its specific transmissivity (or horizontal flow) rate.

Installing raised beds on a roof is much more expensive than on the ground, due mostly to costs associated with rooftop access and labor.  This means that the beds themselves should ideally last much longer on a roof than on the ground, so that they do not need to be replaced very often.  What material should be deployed, then?  Untreated wood typically lasts 3-4 years when used for raised beds in the northeastern climate.  Treated wood lasts longer, but proves toxic when containing edible crops.  Cinder blocks and brick are sturdy options, except that they can easily exceed rooftop weight limits.

Ken Smith Landscape Architect chose cedar for the raised beds at the Embassy Suits Hotel.  This wood naturally resists decay, and therefore acts as an ideal candidate for long-lasting rooftop raised beds.  The downside?  The specific wood used for this project may not have been sustainably harvested, and it was also extremely expensive.  This is a wood that may be prohibitively expensive for most professional projects, and certainly would exceed the budgets of most at-home installations.

So what is the best material to use for rooftop raised beds?  That’s up for debate.  What do you think?

standing room only

The packed audience sat in anticipation as I introduced three panelists at the international CitiesAlive  conference on Friday.

The conference, held this year in Philadelphia,  is organized annually by the Toronto-based Green Roof Professional (GRP) accreditation organization Green Roofs for Healthy Cities.  Unlike other international trade conferences, CitiesAlive is unique in its ability to attract a multidisciplinary audience.  The three-day event acted as a magnet for designers, policy makers, scientists, material vendors, rooftop farmers, green roof enthusiasts, and industry leaders.  The diversity was moving, as was each presenter’s ability to capture the interest of these audiences simultaneously.

Out of the conference’s 12 panel discussions, two focused on rooftop agriculture.  The discussion that I was asked to moderate, Design for Food Production and Biodiversity, highlighted built projects that promote either rooftop farming or green roof biodiversity.  While other sessions on green roof policy and key international projects were moderately attended, this panel discussion was filled to the brim, with standing room only.  Rooftop agriculture is one hot topic.

Scott Torrance, Founding Principal of Scott Torrance Landscape Architect Inc, discussed his process of ecological green roof design.  He developed a biodiversity checklist for these rooftop environments, which considers species diversity, nesting habitat, water sources, and other elements that promote wildlife occupation.  Scott’s talk posed interesting questions with regard to the development of pollinator habitat and pollinator corridors on rooftop farms.

Next, Keith Agoada, President of Urban-Ag, energetically described a demonstration greenhouse that he built on top of a nightclub in California.  The structure was designed and erected with a “guerrilla” approach, without the assistance of an architect or waterproofing consultant.  The small greenhouse is visible from an adjacent elevated highway, and is visited regularly by guests and performers from the nightclub below.

Lastly, Anna Suardini, a Technical Sales Coordinator for American Hydrotech, Inc., discussed the Gary Comer Youth Center in Chicago.  This community center houses a 7,400 sf rooftop row farm that is completely enclosed by higher levels of the surrounding building.  The farm is shielded from the elements, and provides children from the surrounding compromised neighborhood with a chance to work with plants and soil in a safe environment.  The rooftop farm’s success quickly lead to the development  of a larger, at-grade farm near the building.  These community agricultural nodes are effectively fostering a positive food production ethic, whereby children and adults alike become reconnected with their food.

rooftop beekeeping video

Trey Flemming from Urban Apiaries || photo by Lauren Mandel

This is an outstanding WHYY video on Urban Apiaries; Philadelphia’s most popular urban honey producer.

WHYY Rooftop Beekeeping