containers and raised beds and pouches, oh my

In many developed nations we are both blessed and cursed with an obscene breadth of consumer choices.  With a selection as simple as what type of cereal to buy: low fat, high fiber, whole grain, multi-color… decisions can quickly become daunting.  Selecting planters for your home rooftop garden can conjure similar feelings of intimidation, and so here are a few quick steps to select your planters and grease your track to success:

Seedlings awaiting transplant into containers || photo by Lauren Mandel

step 1| Determine your garden’s objective.  What prompted you to build a rooftop garden in the first place?  Do you need herbs for cooking?  Would you like to feed your family and friends throughout the summer?  Defining your goals while considering the size and weight restrictions of your rooftop will start you off in the right direction.  Honestly evaluating your lifestyle and how much time you can commit to watering, staking plants, and harvesting, will also help you determine what garden scale to pursue.  For dainty installations, try focusing on containers and hanging pouches.  If quantity is what you’re after, consider raised beds and self-watering containers.

step 2| Decide what crops to plant.  This will be your garden.  What vegetables and herbs will you enjoy eating and sharing with others?  Each crop prefers a different soil depth, and the height of your planters should reflect these needs.  Select shallow containers for shallow-rooted plants like greens and herbs, and deeper containers for crops like tomatoes, eggplant, and Brussel sprouts.  Keep in mind that deeper soil means heavier planters, so be sure to consult a licensed structural engineer whenever a roof’s structural capacity is unknown.

step 3| Consider using recycled materials.  Off-the-shelf planters can be quick and easy to install, but what if you’re trying to save a few bucks?  Salvaging recycled materials, such as barrels, tins, even old bathtubs, can provide you with the planters you need, without the cost.  Be smart about your selection by avoiding materials that could contaminate your soil, such as pressure treated wood, lead paint, or resins.  Remember also that metal will rust and degrade quickly.

step 4| Let it drain!  Regardless of whether you select containers, raised beds, hanging pouches, or recycled vessels, your planters must drain to prevent root rot.  Most off-the-shelf containers are manufactured with at least one hole in the base, through which excess water is ushered.  Metal containers do not contain drainage holes as consistently as ceramic and plastic pots, so drill or punch out several holes (with a hammer and nail) if none exists.  Hanging pouches are generally made of felt or burlap cloth, both of which are permeable to water.  For raised beds, try installing a hard plastic sheet drain with a high compressive strength (a common green roof component) underneath the frame to allow water to leave the bed.

What types of planters exist in your home garden?  Are you happy with their performance?

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harden off those youngins

Greenhouse seedlings at SHARE Food Program || photo by Lauren Mandel

With spring upon us, greenhouses across the country are full of eager seedlings.  Sheltered greenhouse environments are ideal for sprouting seeds and providing a head start for young veggies, but the real growing occurs outdoors.

Before transplanting seedlings to nearby raised beds and agricultural plots, the youngins need to be “hardened off.”  This involves acclimatising the seedlings to the sun, wind, and variable temperatures they will experience outside.  Farmers have different strategies for hardening off their plants, which usually involves introducing seedlings to the elements gradually.  Farmers may move young plants in and out of a greenhouse, leaving the seedlings outdoors for longer periods each day.  This gradual introduction often lasts for one to two weeks.

When moving seedlings to rooftops, extra care must be taken in hardening off the plants.  As discussed in earlier posts, rooftop environments are much more extreme than their ground-level counterparts.  Skyline farms and gardens are prone to high winds, desiccation (soil drying), and fluctuating temperatures.  So what does this mean for the hardening off process?  Well, the plants should probably be exposed to stronger elements.  This could mean leaving them outside on a particularly cold and windy night, or even bringing them up to the roof for short periods before transplanting.

Anticipating scenarios such as hardening off can help to inform the design of a rooftop farm or garden.  Enough foresight could lead to the construction of a sheltered rooftop area, designed specifically for acclimatizing seedlings.

What techniques do you use to harden off your youngins?

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3… 2… 1… action!

Australian film crew at Eagle Street Rooftop Farm || photo by Lauren Mandel

While standing in the spotlight may be uncomfortable at times, the strategic rooftop farmer embraces the media and “eats up” it’s marketing potential.  Simply put, media coverage can be instrumental in disseminating a farm’s brand.  Print and broadcast media coverage can go a long way, and social media may go even further within certain demographics.  Regardless of whether a newspaper journalist, cinematographer, or blogger visits your rooftop farm, it will behoove you to be accommodating and put your best foot forward.  The media’s relationship with a rooftop farmer, as with any public figure, can be either helpful or harmful in building the farm’s reputation, so be prepared!

Over the past few years, Trey Flemming from Urban Apiaries has learned how positive media relations can go a long way.  Trey and his urban honeybees often appear in magazine and newspaper articles around Philadelphia, as well as in online articles, blogs, and documentaries.  With all the attention, the Urban Apiaries brand has reached new heights: corporate America.  While once available only at local co-ops and specialty stores, Trey’s honey is now available at Terrain – Urban Outfitter’s garden center.

Annie Novak, from Eagle Street Rooftop Farm, similarly embraces media coverage.  When I visited Eagle Street Rooftop Farm in 2011, Annie welcomed me to the roof while in the middle of a photo shoot on the other side of a kale patch.  With a warm air and magnetic disposition, it was no wonder that Annie simultaneously engaged a film crew, a foreign journalist, and myself (the aspiring author).

Annie welcomed each person to the roof with the same friendly smile, before she figured out who they were.  Just remember, out on a roof you never know to whom you may be speaking.

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a retrofit, retrofit?

In the green roofing world we recognize two types of green roofs: those built on new construction, and those built atop existing buildings. The latter is known as a “retrofit.” When considering a retrofit, a structural engineer must confirm that the building is strong enough to support a green roof, and a waterproofing representative must evaluate the roof’s existing waterproofing membrane. If all the stars align, then the retrofit is a go!

3"-thick green roof retrofit || photo courtesy of Roofmeadow

So can a retrofit green roof be retrofit with a rooftop farm? I had never considered this scenario until several weeks ago, when a repeat client of my firm, Roofmeadow, approached us with the question. We designed and built a 13,000 (0.3 acre) green roof for this client in 2007, on top of his factory in NJ. The 3″-thick green roof continues to manage stormwater and perform beautifully, but now the client is looking for more. He wants to grow food on his roof in order to sell to local restaurants and markets.

Luckily, this particular green roof will be easy to retrofit. Green roof systems contain various types of drainage layers, depending on the particular needs of each project. Some drainage layers are made of granular material, while others consist of synthetic sheeting (i.e. plastic peg sheets, egg crates, or tangled filaments). One drainage layer on the market is made out of foam scraps that are salvaged from car seat manufacturing, and bonded together to form a thick mat. In addition to managing the flow of stormwater and retaining water for plants, this multi-purpose layer can protect the waterproofing membrane from shovels and hoes when used in a rooftop farm buildup. Luckily, the green roof in question contains this type of drainage layer.

When retrofitting a green roof such as this with a row farm, the strategy would involve peeling back the top layers of the system to expose the foam drainage layer. Additional green roof media would be brought to the site and mixed with the existing media to create a deeper system. While the existing media contains a very low organic content (4%-6%), the new media would contain more organics to appease the veggies-to-be. Next would come grading, laying out irrigation lines, and planting, and then vwalah – rooftop farm.

Not every retrofit retrofit would be this simple. Nevertheless, there is always a way to figure out a solution, so go ahead and dig in.

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the buzz.

If you mentioned rooftop farming a few years ago, most people would think you were crazy.  But now that rooftop farms and gardens have taken root across the country, more and more people are joining the conversation.  Groups like Cloud 9 Rooftop Farm, the Philadelphia Rooftop Farm (PRooF), NYC Rooftop Farm Initiative, and FarmRoof are talking the talk, and some are just beginning to walk the talk.

Rooftop place-making || photo and rendering by Lauren Mandel

Historically, aspiring rooftop farmers in the U.S. had to seek out rooftops and convince building owners to let the space.  Now, business owners in Philadelphia and New York City are elevating the buzz to new heights by planning for their own rooftop farms.  As the Rooftop Agriculture Specialist at Roofmeadow, I’ve spoken with several of these business owners during the past few weeks.  The prospective projects range in scale from 2,000 square feet (0.05 acre) to 66,000 square feet (1.5 acres), and include row farming and raised beds.  One prospective client even requested rooftop chickens!

Each business owner is interested in rooftop agriculture for a different reason.  Some value the marketing potential of a rooftop farm, others are interested in managing stormwater, and others want to supplement their commercial kitchens with roof-grown food.  Regardless of intent, the rooftop agricultural buzz is growing.  It’s growing all around the country, and it’s going to be big.

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who are these people, anyway?

Rooftop farms and gardens are sprouting up in cities across the country.  Restaurants, community groups, families, and individuals are enjoying the bounty, but who the heck is up there growing all this food?

Volunteer at Eagle Street Rooftop Farm (Brooklyn, NY) || photo by Lauren Mandel

Lots of people – that’s who!  People of all different ages and ethnicities, with different skill sets, and different reasons for growing food.  American rooftop farmers tend to be between the ages of 22 and 55, with men and women equally engaged.  Most, if not all of these farmers migrated to rooftops from ground-level farms.  Some came from urban farms, and others from more traditional rural farmsteads.  Farmers who land these highly-prized rooftop positions are generally very knowledgeable about their agrarian genre – whether it be row farming, beekeeping, or hydroponics.  It is rare that a newbie finds himself in charge of much on the skyline.

Trey Flemming of Urban Apiaries (Philadelphia, PA) || photo by Lauren Mandel

Farm interns are a pillar of small agrarian farms.  In this young industry, however, formal trainees are few and far between.  The rare rooftop farm intern generally falls on the younger end of the spectrum, and carries her position for one to two growing seasons.

Volunteers, on the other hand, are key players in most rooftop endeavours.  These are the passionate folks who lend their time and energy in exchange for the experience alone, and maybe some fresh veggies on the side.  Farm volunteers are sometimes much younger or older than typical rooftop occupants.  They may enter the roof from a marginalized, inner-city neighborhood, or form another unsuspecting environment.

Vincent Dessberg of I Grow My Own Veggies (Sarasota, FL) || photo by Lauren Mandel

Laborers are common in large-scale, high-yield commercial farms.  Hydroponic facilities like Gotham Greens are structured to support a crop of highly-trained workers.  The pulse of rural farms across the country relies on migrant labor.  By contrast, the high-profile nature of rooftop farms tends to attract a very different workforce.  At this point in the fledgling industry’s development, commercial hydroponic farms are the only type of rooftop farm that can afford to pay workers aside from the farmer.  Perhaps this will change as the industry becomes more established.

We’ve now covered the key farming players, but what about rooftop gardening?  By 2009, the National Gardening Association found that 50% of American households grew some portion of their own food.  This astounding statistic means that anyone can be a rooftop gardener!  What’s your story?  Tell us about your own rooftop gardening experience, and you could land yourself  in one of the Eat Up volumes.

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“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?

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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.

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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.

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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.

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