We’re seeing cities going green in greater numbers. Within a few decades, various cities throughout America will be struggling with populations of 20 million people and up. Imagine the difficulties this will engender given that current metropolitan stressors are already almost unmanageable. For instance, many lower- to middle-income urban families can’t afford fresh food. Wildlife must adapt to city life, causing problems for both people and animals. Storm runoff leads to flooding in many major cities, which creates a multitute of other expensive complications. Buildings absorb the heat of the sun with little dissipation rate, so temperatures increase in downtown areas to harrowing levels. This, in turn, raises utility bills. And so on.
To mitigate these and other problems, a number of cities are turning to rooftop gardening, a burgeoning green movement that encourages the planting of gardens, grasses, and trees on the tops of city buildings. The benefits prove especially valuable for those who most need them. Access to fresh fruits and vegetables is essential to maintaining a healthy diet.
However, many city dwellers can’t easily obtain these simple necessities. They don’t have access to land where they can grow their own fruits and vegetables, or the expenses of buying fresh produce don’t fall within their budget. Urban gardening can help supplement part of this problem. Private citizens with access to rooftop gardens or community gardens can now bring home at least a small amount of fresh produce to help with dietary needs. Of course, they also save money by spending less at the grocery store.
Urban businesses are beginning to reap benefits from rooftop gardens as well. Tony Tomelden, owner of The Pug, a popular Washington D.C. bar, now grows his own tomatoes and chilies for Bloody Marys. His garden attracts a growing number of consumers in America who now look for locally grown produce. It will also reduce the amount of cash he must spend on these vegetables. Of perhaps greater significance, Tomelden receives tax subsidies from the government for having a green roof.
The urban education system is adopting a more elevated environmental consciousness, too. P.S. 6, a school in New York’s Upper East Side, will soon start growing vegetables and herbs to serve in the cafeteria. The school’s garden will help reduce their food budget, improve everyone’s nutritional intake, and provide an educational opportunity for the students as they help with gardening duties for class.
All this plant life improves the environment for other living things as well. Large rooftop gardens provide wildlife corridors for birds and insects, as well as shelter from predators and difficult weather conditions. The pollen and nectar from flowering plants also provide a source of food for these creatures. Bees especially benefit from rooftop gardens, and in return cross-pollinate gardens and crops from all over the city. In fact, many people who cultivate rooftop gardens have started building apiaries (the boxes the beehives of honey bees are kept in) to go along with the gardens.
Bees pollinate approximately 80 percent of flowering plants and 75 percent of fruits, nuts, and vegetables in the United States. Bees travel between two to seven miles from their hives to pollinate these plants. The apiaries not only produce fresh honey for the gardeners, but they offer the additional benefit of housing hundreds of living pollinators that can fly between various gardens to increase the genetic diversity of flowering plants populating every corner of any given city.
Infrastructural decay might be one of the biggest problems on the horizon for American culture. Many cities just don’t have the money right now to fix outdated drainage systems. After major storms, this can cause flooding, which in turn costs the city and citizens money to fix water damage and clean up. Rooftop gardens help slow the runoff process (if the roof is properly reinforced) by absorbing some of the rainwater and slowing even more water as it filters through the dirt, rocks, and roots of the gardens. This process allows the drainage system to take the water on at a slower pace.
The same process also helps filter out pollutants the water picks up from the air. This natural filtration process lessens the strain on the water treatment parts of the drainage systems. Singapore recently passed a law requiring all new and retrofitted buildings to have green roofs to help alleviate the amount of water going through their current drainage system. Officials there claim they will eventually replace their current system, but the law helps extend the time they need to find the money and materials to build the new system.
On the other extreme, sunny days can raise temperatures to unbearable, dangerous levels. Due to the poorly chosen roofing materials used on many buildings, the heat absorbed by these surfaces doesn’t dissipate effectively. This causes the ambient heat of the building and surroundings to increase. Scientists call this the “Heat Island Effect.”
A study comparing a traditional and green roof showed the huge impact that green roofs have on reducing the temperature of the building. Monitors tracked the temperature of both roofs over the course of two years. The traditional roof reached temperatures of 158° F, while the green roof rarely reached temperatures above 86° F. Heat flow through the roof showed a 95% heat reduction. Of course, this also reduces utilities bills for residents living inside the building in addition to reducing the Heat Island Effect. It’s also worth noting that heat conservation during winter saw a 26% increase, ultimately meaning much lower year-round utility bills.
Given roof gardens’ many benefits, one would imagine them sprouting up everywhere, but certain problems still need to be resolved. The initial cost of building a roof garden exceeds that of a traditional roof. In addition to the materials to build the garden, the cost for soil, seeds, plants, and water to maintain the garden also increase the starting budget. Areas prone to drought have the problem of additional water costs. Older roofs will need inspections and reinforcements to make sure they can bear the weight of the soil for the gardens.
The creation of intricate irrigation and drainage to direct water flow through soil beds and off the roof also adds additional costs and time during the construction phase. If a puncture occurs in the moisture protection membrane and allows water into the roofing material, a whole section of garden will need removal and replacement before repairs can be made. Insurance companies also tend to raise premiums on buildings with rooftop gardens.
Difficulties relating to soil weight and possible water damage can be avoided through various means, but one strategy continues to gain prominence. Hydroponics can solve the problem by reducing the weight of materials needed and using less water. Most hydroponic gardens use less than 10% of the water that traditional agriculture uses. Hydroponics removes the necessity of the soil medium for plants and replaces it with an inert medium like gravel, clay pebbles, or mineral wool soaked in a nutrient solution; or, gardeners can suspend the plants in a nutrient solution.
They may also infuse this solution with oxygen and deliver it to the plants in a mist form called “aeroponics.” This reduces the weight strain placed on the roof while taking up less space on the roof. This extra space allows for more plants or any other additions someone may with to add to the garden. The plants also tend to mature quicker, grow larger, and remain healthier longer. Commercial products to create hydroponic gardens can be purchased online. One can even find instructions on how to build your own with materials as cheap as PVC piping.
Solutions exist for other problems, too. Many cities have tax incentives for planting roof top gardens to help offset the initial cost and insurance premiums of certain types of gardens. Planters also have the option of creating simpler gardens that cost about 10 dollars per square foot with an annual cost of 75 cents per square foot. Gardeners who have issues with local watering requirements also have the luxury of using hydroponics or creating drought-resistant gardens.
Overall, the benefits of rooftop gardens outweigh the upfront costs of construction. People everywhere can adapt these gardens to their own individual needs and preferences. Granted, some may try to claim time as a concern, but lets get real. If they spend 15 minutes less a day watching T.V., playing video games, or cruising the Internet for porn and pictures of cats, they’ll have plenty of time to tend the garden and become more well-adjusted, happier urbanites. Anyone who has even the slightest interest in gardening can start a small garden, then slowly expand it to ideal specifications. Rooftop gardens in every city across America will not only grant the cities the benefits mentioned above, but they will also beautify the country even more. If Babylon can do it, so can we.
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Jonathan Read is a writer from the Colorado Springs area.
