Pollinators for Urban Gardens: The Case for Hole-Nesting Native Bees

Note from the Battery Rooftop Gardener: Crown Bees, which bills itself as the “The Gentle Bee Company,” is a solitary bee (mason and leafcutters) company based in Woodinville, WA that advocates using managed native bees for pollinating fruits and vegetables (see www.crownbees.com ).   I invited Demarus Sandlin of Crown Bees to explain the potential of native bees for urban farmers.  Her guest blog follows.

Urban gardens face a host of special problems: space restrictions, sunlight availability, water sources, and excessive heat.  Pollination is perhaps the most fundamental issue of all for those of us who grow food. Should we also raise honey bees or just hope that local wild bees will visit our plants?DerekArtz

Mason bee on almond flower. Photo by Derek Artz.

Honey bees are sophisticated pollinators but they have their drawbacks. Originally imported mainly for honey production, they arrived to the Americas from Europe in the early 1600’s. By WWII, honey bees were viewed as farmland’s principal pollinators.

But the natural pollinators of our farms have always been our native bees.  North America is home to 3,600 species of native bees. About 90% of these bees are solitary, which means they do not form hives. Instead, each female builds her own nest. Solitary bees are gentle and do not aggressively defend their nests. Many native bee species nest in the ground, the rest in empty stems or holes.

Mason bees and leafcutter bees are native hole-nesting bees that are now being increasingly used by farmers and gardeners as pollinators. These native species should be preferred for many good reasons.   A diversity of bees doubles or triples food production and an introduction of bees in a location without managed bees increases yields by 25%.  This is because our native bees, which carry pollen dry on their abdomens (a larger surface area than the leg pouches that honey bees use), are about 30% more efficient at pollination than honey bees.

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Female mason bees wait in nesting holes for good weather. Photo by Demarus Sandlin

Hole-nesting bees can be easily moved where needed because they over-winter in cocoons either as larvae or young adults. In the spring or summer, simply place their cocoons in a new nesting house and they emerge, returning to lay next year’s bees.  Harvest their cocoons in the fall, store in a small box in your fridge, and you will have a guaranteed healthy generation of bees for the next pollination season. Hole-nesting bees have the added advantage of not flying far for forage. Their range is about 300 feet, which means that wherever your garden is located the bees will stay nearby to gather pollen and nectar.

There are some things to consider when raising mason and leafcutter bees in an urban setting. They need morning sun for energy to start flying. A rooftop garden’s temperature could be warmer than a mason bee would like (they are spring bees that emerge when weather is about 55 degrees). The bees also need warmth in the afternoon; too much shade could leave them lethargic.  A rooftop garden may be too windy at times and the nesting house should also be carefully placed for protection. Nesting material for building egg chamber partitions is important as well. Mason bees need clayey mud and leafcutter bees use small pieces of soft-celled leaves for building nesting chambers.

Mason and leafcutter bees are easy-to-raise, cheaper than honey bees, safe, and fun. When we use them, we improve ecological health and diversity by reintroducing a native species and providing attractive habitat that other hole-nesting insects also will appreciate.

By Demarus Sandlin, Crown Bees

Posted in Biodiversity, Urban Agriculture and Food Policy, Wildlife | Leave a comment

Getting to Green

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If you have read this blog for some time, you will know that my adventure in urban rooftop agriculture is just one manifestation of a broader interest in environmental issues.   Having spent more than two decades working for various Green causes, I am frustrated by our lack of progress.   My diagnosis of the problem, and practical suggestions for how to move forward, are the subjects of my new book, Getting to Green, Saving Nature: A Bipartisan Solution (to be released by W.W. Norton on April 18).

To make environmental progress in the United States, we need to acknowledge the diversity of perspectives on environmental issues and deal with the country as it is, not as we might wish it to be.  Please have a look at the following short video trailer for the book:

You can learn more at the book’s website.  If you want to buy it, here are links to the book on the main on-line purchase sites:

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If you are in or near New York, I will be speaking at the Upper West Side Barnes & Noble on April 18. The details are here.

The book tour is taking me to San Francisco, Denver, Austin, Boston, and Washington, so if you are near any of those places, please come. I love to meet fellow rooftop farmers and urban agriculture enthusiasts.   You can find details of all tour events on the book’s website or Facebook page. Please also check out my Twitter feed.

When I come home, I hope to enjoy the first rooftop strawberries of the season.

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Posted in Strawberries, Urban Agriculture and Food Policy | Leave a comment

Manhattan Rooftop Terroir

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Today I enjoyed the first rooftop asparagus of the season, which of course raised the knotty question of Manhattan rooftop terroir.

Let’s start with the question of what terroir is: the unique, organoleptic qualities associated with food and drink from a specific place, reflecting that place’s distinctive blend of mineralization, soil chemistry, moisture, temperature, altitude, slope, and light. Or, for the geneticists out there, think epigenetics: the genes of two plants may be the same, but their expression differs depending on the environment in which the plant is grown. More recently, writers such as Rowan Jacobsen (American Terroir) and Robin Shulman (Eat the City) have advanced a concept of cultural terroir, encompassing regionalism and tradition or, as Jacobson puts it, “a partnership between person, plant, and environment to bring something unique into the world.”

Asparagus, you might be thinking, are not like wine, oysters, or other foods we most associate with distinctive terroir; don’t they taste pretty much the same wherever they are grown? Mais non. The great French chef Yannick Alleno is definitive: the same breed of asparagus grown in Vallauris, near Cannes, will taste differently if grown in California: “This,” he argues, “is where terroir expresses itself.” And in large part due to his influence, the French have embraced the concept of urban terroir, epitomized by Chef Alleno’s fine restaurant, Terroir Parisien, which features artichokes from Paris, asparagus from Argenteuil and cabbage from Pontoise (both northwest suburbs), and peaches from Montreuil (only 6 km from the center of town).   So if there is a terroir Parisien, mustn’t there be a Manhattan terroir? And a terroir expressed by growing food 35 floors above The Battery?

The first objection to the idea of rooftop terroir would doubtless be that the green roof is a wholly artificial environment, without any “natural” or indigenous soil conditions.   But this objection does not withstand scrutiny. Many of the most celebrated ground-level terroirs result from centuries or even millennia of human manipulation. Moreover, although a green roof has no invariable soil condition, it certainly is completely distinctive in its combination of other physical characteristics (moisture, temperature, altitude, slope, and light) and as an expression of the culture of the place and the practices of the farmer.   So, bien sur, each rooftop garden has a distinctive terroir. And the whole notion of urban rooftop terroir must be counted among the great unexploited potentials of urban agriculture: we have yet to discover which plants respond to the conditions of urban life and green roof cultivation with an expression of flavor that is especially interesting or desirable.

And my rooftop asparagus? How did it express terroir?   I honestly cannot say. The answer requires disciplined comparison of my rooftop spears with others of the same variety grown elsewhere. An experiment for another day. But in the mean time, my first spear of the season tasted clean, bright, moist, with just the right amount of gentle crunch, and a mild green flavor enhanced by an undertone of earthiness.  Happy spring to all.

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Posted in Cooking and Eating, Design, Soil, Urban Agriculture and Food Policy, Weather | 4 Comments

The Rooftop Growing Guide

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Since the 18th century the country’s heartland has sprouted a hardy crop of farmer philosophers. The 21st century Brooklyn-based example of this great American type is Annie Novak. Her new book, The Rooftop Growing Guide (Ten Speed Press, available February 16) not only gives us the perfect recipe for rooftop soil, but quotes Virgil and Proust. She invokes Aldo Leopold before revealing the mysteries of growing vegetables in containers. The sensibility of Wendell Berry is woven into every page. The barriers between rural and urban, ground and roof, and ancient and modern all collapse as Annie Novak invokes the timeless and universal connections between humans and their food. The reader soon discovers that vegetables have not been the only yield from seven years of rooftop gardening; Annie Novak’s harvest includes a bumper crop of wisdom.

As someone who has developed and maintains a large rooftop garden, I know first hand the scarcity of sound advice.  There are few experts because there are few people who have been doing rooftop farming long enough to make the transition from student to teacher.   Annie Novak has, and is the country’s most authoritative source on the subject. But authority is one thing; the ability to translate that knowledge for the uninitiated is another. Rooftop Growing Guide does this beautifully. It is supremely well organized, user friendly, and clear.   So it’s simple:  If you have a green roof, think you might someday have one, or even dream of growing tomatoes on your fire escape, you need to own this book.

But even if you don’t have a rooftop farm in your future, anyone interested in urban agriculture – whether from the perspective of environmentalism, public health, or urban planning – will profit from spending a couple of hours with the book.   You will come away understanding what rooftop agriculture really looks like, and having explored the many aspects of the case for growing food in the city.

And, for the followers of this blog, you may be interested in the photographs of Battery Rooftop Garden and will enjoy a lovely short essay by Annie on the creatures that make this garden their home.   Annie Novak has been the farmer-in-chief at BRTG since its inception. I hope you will support her, and indulge yourself, by buying the book.

Posted in Photos, Soil, Structure, Urban Agriculture and Food Policy, Vegetables, Wildlife | 1 Comment

Breaking News: Urban Fruit is Better

A few years ago, I told an environmentalist friend of mine, who is also a medical doctor, about my green roof and plan to grow food.   She looked at me strangely, obviously torn between disapproval and an instinct to be polite in the face of my enthusiasm for urban agriculture.   Finally she shared her opinion that urban food production was dangerous, due to the high levels of lead and other contaminants in so many urban soils. I explained that green roof soils were sourced from outside of the city and no more likely to be contaminated that any others.   She pointed out that, even so, I was not immune from atmospheric disposition of contaminants, and we dropped the subject.   Ever since, somewhere in the back of my mind, lurked a worry that perhaps she was right.

So I was delighted to discover that the League of Urban Canners, an urban harvesting collective in the Boston area, asked Dan Brabander, professor of geosciences, and his students at Wellesley, to tackle this question. Professor Brabander and his team examined 166 samples of apples, peaches, cherries, and other fruits and herbs sourced from urban farms in Cambridge, Somerville, and Boston, and then conducted a laboratory analysis to determine lead levels as well as concentrations of micronutrients. The result, as reported in their paper: “consumption of urban fruit does not represent a significant lead exposure pathway that merits immediate concern.”

But here’s what I found most interesting: nutritious calcium concentrations in urban apples and peaches were more than 2.5 times those in their commercial counterparts, and the amount of other beneficial micronutrients were higher in every type of urban fruit tested. Their conclusion, in the careful language of science: “On average urban fruit contains a wider range of micronutrients than their commercial counterparts.”   But why? That’s a question for another day.   In the mean time, I will be serving my guests Battery Rooftop Garden’s Asian and European pears, peaches, plums, nectarines, and apples without guilt, and with the satisfaction that they are almost certainly more nutritious than the store-bought alternative.

With thanks to my cousin Amy for bringing this study to my attention. If you want to read the full paper, click here.

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Posted in Apples, Asian Pears, Cooking and Eating, European Pears, Fruit, Nectarines, Peaches, Pears, Plums, Soil, Urban Agriculture and Food Policy | Leave a comment

Hot, Hot, Hot — Part II

The interview with Suzanne Roberts on Headline News (see previous post) was part of her show, “Seeking Solutions with Suzanne,” which aims to give practical advice to retired Americans.

Her visit was followed a couple of days later by the Wall Street Journal and Barron’s, whose audience is a bit different.   Their video site is, in fact, quite specific: “advice for families with assets of $5 million or more.”   On Tuesday, I found myself trying to convince retirees that they can grow vegetables in plastic tubs on the fire escape, and on Thursday my job was to convince millionaires to raise their sights and tell their architects to forget the media room and give them vegetables on the roof.

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The Dow Jones videographer took some stunning footage of the garden (to be featured in a subsequent post), and asked the questions off-camera.  Have a look at the resulting program, at http://www.wsj.com/video/growing-rooftop-food/A42055EB-D36A-42A0-BF99-B85BF3A86A84.html .

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Posted in Urban Agriculture and Food Policy | 1 Comment

Hot, Hot, Hot

No, I’m not talking about the genus Capsicum, whose many species of peppers thrive on a green roof. I’m talking about green roofs themselves.  For years, we rooftop farmers have attracted the attention of periodicals like Urban Farm and Living Architecture, worthy to be sure, but hardly mainstream.   This year, that seems to have changed.  In one week earlier this autumn three separate video crews dragged their equipment to the 35th floor to explore the wonders of urban agriculture.

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The first of those – an interview with Suzanne Roberts on Headline News Network (HLN) – airs tomorrow, Wednesday November 12 at 1:24 PM Eastern Standard Time.  If you miss it, you can see a truncated version of the interview at http://www.suzanne.tv/show.aspx?sid=1051 .

Following shortly: links to the Wall Street Journal/Dow Jones/Barron’s Penta show on BRTG.

Posted in Urban Agriculture and Food Policy | 3 Comments