• Urban Greenhouses ➞

Urban Greenhouses: Growing Future Food for a Better Tomorrow

"Green miles" might be a term you’ll hear bandied about when people start talking about food. Other terms might be ethical, ecological, organic, or natural. With a wide assortment of ways to grow food and different types of food from innumerable growing sources, you might be a little confused about it all.

Growing your own or buying locally grown cuts through a lot of the chatter having to do with food. If your salad is grown in the greenhouse down the block, you probably know how that grower treats his or her workers, whether chemical fertilizers are used, and if pesticides are a part of the growing plan.

If you grow it yourself, you have an even better idea of the history of the leaf of lettuce that is on your BLT, or even the provenance of the lemon in your lemonade. The very shortest green mile possible for any food is directly from your windowsill to your table. But that might not be possible for everyone.

Or is it? Urban gardening is becoming increasingly popular. Urban greenhouses make it possible to grow nearly any kind of food at any time of the year. Growing food is like many other things. There is a learning curve. You do have to be persistent and work at it. With just a little bit of tutelage and the right opportunity, nearly anyone can grow at least a part of their food. That is where urban greenhouses come in.

Urban Greenhouses and the Future of Food

Urban greenhouses have the potential to not only lower the cost of food for city dwellers, but to also increase food security, and to even provide jobs for city dwellers. City-sponsored food growing projects can help individuals learn how to garden, and give them some idea of what is needed to raise a plant from seed to harvest. Greenhouse projects in cities can range from large commercial growing companies to city park services and down to the windowsill terrarium for apartment dwellers. Greenhouses certainly can cut down on the number of miles that a head of lettuce must travel from its point of origin to your dinner table. As more and more miles of what was formerly farmland is given over to urban development, and as costs for transportation increase, greenhouses not only stretch seasons but provide contact with growing things for those who work or shop in them.

Urban Rooftop Greenhouses

As with much of urban farming, urban rooftop greenhouses are a matter of scale. For example, there are large companies that have built and maintain greenhouses on the tops of skyscrapers. These huge operations are like adding another floor onto an already large building. This is an economical use of space, especially since gardens placed at ground level among these giants might not receive enough sunlight for good growth.

If the high rise is an apartment building, the rooftop greenhouse has the potential to fulfill several niches. First, it can provide food for the people living in the building. Whether developed as a coop or as a commercial endeavor, if food grown on the roof is sold or provided to the people in the building, these are munchies that do not have to be loaded on a transport truck or shipped on a boat. By their very nature, greenhouses have the potential to control the growing environment, allowing for plants to be grown that might not survive outdoor weather.

Small-scale rooftop gardens might be a simple geodesic dome with a few rows of salad greens and a potted citrus tree or two. Even if there is only enough room for a tray or two of microgreens and a chair, it creates a place where the gardener can enjoy the sunshine and a few bits of greenery.

Urban Farming Greenhouses

Large scale urban farming greenhouses can be ground-level expanses of glass and steel, or they can be rooftop gardens that take the place of the proverbial penthouse. The best glass for greenhouses, large or small, on the ground or on top of a building is double-paned toughened safety glass. The double panes help slow heat loss during the night or on cloudy days, while it is the most likely to survive a blow. Should it break, it crumbles into pebbles, rather than becoming shards that could cause injury. The only problem with it is that the initial investment can be rather high.

Orangeries, conservatories, and greenhouses have been used to grow-out-of-season crops for centuries. The older buildings of this sort were often parts of estates by landed nobility. In more modern times, corporations shoulder the initial cost of building and setting up urban greenhouses. This, of course, means that large urban greenhouses can and frequently are a form of agribusiness.

Polycarbonate sheeting provides a less expensive alternative. The initial cost is less, it is easier to handle by the DIY crowd. Its disadvantage is that it is also less durable and more easily damaged by storms. However, if a greenhouse needs to go up quickly and will be assembled by amateur labor, polycarbonate sheeting is an excellent material to use when adding a season extender to your home or in developing a low-cost lean-to greenhouse as a community project.

Back in the 1960s through the 1990s a group called the New Alchemy Institute conducted experiments in home growing, including a form of attached greenhouses. These handmade structures were incorporated into a home’s general living space and involved passive solar heating as part of their design. New Alchemists.net continues the work, designing what they call bio-shelters. These structures incorporate fish, insects and other plant-compatible life-forms into their operating designs.

Greenhouses might use standard growing trays or they might experiment with vertical growing methods. They might use trays or pots of soil, or they might grow plants in nutrient baths. This latter method is often known as hydroponics. In a few cases, sides of tall buildings have been used for growing crops or ornamentals. This latter method, however, is still somewhat experimental.

While greenhouses as urban technology might be less well-known than farming outside the city limits, greenhouses on rooftops, vacant lots or even city blocks are not unknown. When incorporated with other food programs, urban greenhouses have the potential not only to provide food stability for inner cities, but to increase options for employment, to occupy youth who would otherwise be without work, to provide green sanctuaries for people whose minds need a rest from urban busy-ness, and to reduce green miles for many types of food.

Small Urban Greenhouses

Not all greenhouses are owned and run by corporate conglomerates. Today’s glazing technology makes it more possible than ever before to incorporate a small greenhouse into an existing home or apartment building. Small urban greenhouses might be part of a grocery store or restaurant. Or they could be a backyard garden greenhouse or even a rooftop greenhouse. They could be situated on a balcony or even attached outside a window. In the very strictest sense of the word, a terrarium is a mini greenhouse. Nothing highlights the human desire for beautiful, nutritious plants growing in the kitchen than the current microgreens craze. The internet abounds with directions for transforming a kitchen cupboard into a mini-garden by using artificial lighting and a growing kit. Harvested in the leaf stage, these mini-plants can provide both added nutrients to a city-dwellers diet and the personal satisfaction of taking control of at least one small part of one’s own diet. An urban greenhouse can also be a social center, especially if it is part of a sponsored food program. People might meet there informally as they care for a tray of vegetables or ornamentals. Or they might gather for formal meetings to discuss operations of the greenhouse or to plan for its future, or just to celebrate a successful harvest. Food centered social events are certainly not new in the history of humankind.

Urban Garden Greenhouses

As part of the movement away from manicured lawns and toward using that space to grow food, the backyard greenhouse might take the place of the pergola or gazebo. Drive past any storage building manufacturer, and you will probably see a cute little greenhouse tucked in beside the faux barns, playhouses, and similar mini-buildings. For homeowners or even for people who rent houses or duplexes, lean-to greenhouses that might be nothing more than a frame with shelves and a zip-up front like a tent make excellent season extenders. By definition, cold frames and hotbeds are also a sort of greenhouse, and can easily be accommodated at the edge of a garden.

Rooftops are also a place to “plant” a miniature greenhouse. These might not be much more than a geodesic dome made of triangles of tempered glass placed in frames. Or they could even be frameworks with heavy plastic stretched over them, granting the opportunity for starting the rooftop garden early.

Miniature greenhouses can also be space extenders for a home that is challenged for space. The greenhouse can be a place to withdraw from noisy children or the demands of a busy adult household. In areas where winter sunshine is at a premium, the greenhouse can be a warm, protected spot where the gardener can soak up a few rays before the elusive winter sun slides down over the horizon.

Urban Balcony Greenhouse

For many apartment dwellers, a balcony is their only personal outdoor space. Frequently, these balconies are no more than six feet deep by the general width of the apartment, or perhaps a little less. There might be concerns about the combined weight of planters, potting soil, and plants, especially with older buildings where the “balcony” might be little more than a fire escape. Adding the weight of a small greenhouse could be an issue.

Fortunately, there are several lean-to greenhouse models that can easily fit on most balconies. Some of them are scarcely more than a tent fitted over a set of shelves but can serve to protect tender perennials or act as a season extender. Products such as vermiculite potting medium can also help with the weight of soil, although nothing will off-set the weight of water – which is essential to most growing things. Even cacti require a little of it.

A more formal balcony greenhouse might be planned into the building. Hopefully, the architect will have taken the angle of the sun at various changing seasons where the apartment is located. A planned balcony greenhouse might be set up to share heating from the main part of the unit, and could even have room enough for a small table and chairs.

Some modern apartment buildings, where growing things on the balcony is planned into the structure, can resemble a vertical farm during the summer growing season. These should not be confused with farmscrapers, which is a relatively new technology. The planned greenhouse balcony is an older technology that has been adapted to the modern trend of building upward to get more space out of a patch of earth.

Urban Window Greenhouses

For apartment dwellers with operable windows, these are a means of having a garden greenhouse when no other space is available. Designed to be installed outside the window, they provide enough room for a tray of seedlings or microgreens, while adding visual interest to what might otherwise be a bleak outlook. They are frequently the perfect location for sun-loving herbs that find an ordinary windowsill a little too dark or a way of creating a protected space for plants away from pets or small children.

No matter how large or how small, urban greenhouses can make a difference in the food supply and to the personal outlook of the city dweller. Urban greenhouses come in all sizes, from big corporate food operations down to a shelf of microgreens with artificial lighting. They can serve as season extenders for a gardening operation of any size, or they can create a year-round controlled environment for plants that have been moved from their natural growing location. Best of all, they can go a long way toward helping provide food security for people who live in cities.