With outdoor space at a premium in many cities, gardeners can turn to rooftop landscaping. Whether you want to grow organic produce, creating an oasis of green, reduce your carbon footprint or simply enjoy gardening as a hobby, the roof landscapes provide the means. Many roof gardens to grow solely on rain water so that they are environmentally friendly and sustainable. Rooftop landscaping also reduces cooling energy needs of buildings by up to 25 percent and extends the life of the roof from 10 to 40 years.
Rooftop Landscaping requires structural considerations, particularly regarding sustainability. Before laying sod or soil, determine your building, the load per square meter limit. The weight of the soil, add plants and moisture quickly. For example, the 1-hectare, or 40,000-square-foot Brooklyn Grange Farm (brooklyngrangefarm.com) in Queens, New York, 1.2 million lbs. of the soil, or from about 30 lbs. per square meter.
Green Roof Systems
Rooftop landscapes require layers of protection between the roof and the garden base. These layers are called "green roofs" and can be extensive or intensive. Extensive green roof systems weigh less, require less maintenance and contain a shallower region. In contrast, intensive roofs more weight and require more irrigation and cutting, but more like a traditional, earth-based garden. Systems, layers of root barrier, waterproof membranes, felt, drainage materials and containers consist of excess rainwater. Your roof, structural capacity, and weight-bearing status determine the green roof, which is most appropriate.
Once your green roof system is installed, select your growing media. The best types are lightweight, easy to empty and provide moisture and nutrients for plants. Specific mixtures of soil for roof landscapes are commercially available. Many contain mixtures of light stone, recycled materials and organic compost. Apply as low a volume of media as possible as part of your roof, the structural capacity. Rooftops experience more wind than the bottom, so use a wind blanket around plants until they are established.
Whenever possible, use native plants. Native species are adapted by nature to the conditions in your area, such as rainfall, temperature range, pests and diseases. In selecting the types, choose those that heat, drought, cold and high winds tolerated, as all of these conditions on the roofs can be increased. Many herbal plants grow well on roofs, such as beans, beets, carrots, fennel, vegetables, herbs, tomatoes and radishes. If you live in a cooler climate, the landscape with winter cover crops such as buckwheat, clover, rye or vetch. Low-growing ornamental plants that grow well in roofscapes include blue fescue grass, cacti, ice plants, penstemon leaf pine and sage.