The author of the text is Dr Przemysław Bąbelewski
Roof gardens, colloquially called green roofs, have been accompanying people for hundreds of years.The first information on this topic comes from the 7th century BC from Mesopotamia, where the famous Hanging Gardens of Babylon were built. They were set up on artificial terraces, the number of which was around 100.They were called hanging gardens thanks to the illusion of trees that looked as if they were floating in the air from a distance.
In the vicinity of the Mediterranean Sea, roof gardens were built in honor of Adonis, while in Northern Europe, the Scandinavians for centuries covered their roofs with peat and grass.
In order to set up a roof garden, the roof must meet the appropriate technical requirements, and above all, it must be able to withstand additional loads. The structure should be able to withstand a load of 70 to 500 kg / m².This load depends on the plants planted, the thickness and type of substrate, as well as rainfall and snowfall.
Green roofs in practice
Currently, there are two types of green roofs: extensive and intensive. This division is made on the basis of the vegetation used, the thickness of the ground and the way the roof is used.
Extensive roofs are areas that are not utility gardens, but green areas. Staying in such a "garden" is associated only with maintenance work. Substrate layer
in this type of assumptions it is very shallow, it ranges from 3 to 8 cmOnly species that naturally come from places where the conditions for the development of most plants are difficult or even inappropriate are suitable for planting these roofs. Such plants should be resistant to strong sunlight, strong wind, frost and a small amount of rainfall.
Low-growing, fast-growing and creeping perennials are most suitable for this type of plant. Swarms, sedum plants or other rock plants, such as thyme, will be ideal here.Most perennials of this type can withstand long periods without waterThe most popular are: white sedum, rock sedum, flower sedum, hybrid sedum, equine sedum, Caucasian sedum, carduzole carnation, Doerfler thyme, thyme sand, keratosis, staphylococcus.
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(zdj .: Fotolia.com) |
Intensive roofs are intended for recreational and leisure purposes.The vegetation layer here is at least 25 cm and may reach 45 cm. When the layer is 15-30 cm thick, perennials are used, at 30-40 cm, shrubs can be used, and trees should be grown in a layer above 40 cm.The maintenance of such gardens is very expensive, and moreover, they require a special building structure adapted to high loads.The advantage of this type of arrangement is the large selection of plants used for planting.
In a layer of 15 cm or more, the following can be planted: common periwinkle, Carpathian bellflower, narrow-leaved lavender, spiked rotator, evergreen garment. Perennials above 20 cm grow well: Siberian iris, paniculate flame, Japanese tawulka, whorl. The following bushes grow well in a substrate 20-30 cm thick: Thunberg's barberry, evergreen boxwood, Chinese juniper, Fortune's euonymus, bush cinquefoil, Japanese quince.In the layer over 40 cm, the best growth is: privet, wrinkled rose , Canadian yew, and from conifers always green Lawson's cypress,thuja , yew The trees will be represented by the common maple "Globosa", the field maple or the black locust "Umbraculifera".
Roof gardens are different from classic gardens where plants can grow freely and have good access to water and nutrients. In roof gardens, the individual layers on the roof base are important, among which the vegetation layer, the vegetation layer, the filter layer, the drainage layer, the protective layer, the root barrier and the separating layer.
Green roof construction
When starting the construction of a green roof, remember that it is an extremely expensive investment. It is also very important to hire an appropriate company dealing in the construction of green roofs, which, from design to implementation, will reliably undertake the greening of the roof.The arrangement starts with checking the roof structure's resistance to loads, then all layers are installed one after the other, starting with the separating layer and ending with the vegetation. During the first weeks after setting up the garden, you should regularly check the moisture level of the substrate and, if necessary, water it.
Extensive assumptions require care twice a year, consisting in cutting out faded plants or watering in very dry periods. Under intensive assumptions, care must be carried out regularly.First of all, it consists in mowing the grass, removing weeds and faded flowers or systematically irrigating.
Green roofs in Poland
The biggest roof foundation in Poland is the green roof on the library of the University of Warsaw, where the gardens have an area of over 15,000 m².
This garden was established in 1996-2001, 7,000 deciduous trees and shrubs, 1,000 climbing plants and 2,000 conifers were planted there.Irena Bajarska, a designer, divided it into the following interiors: the Golden Garden with the Japanese Tawula 'Goldmound' and the shrub cinquefoil, the Carmine Garden with various varieties of roses and the wonderful bush of the 'Purpurea Nana' variety, the Green Garden planted with grasses and Dammera cotoneaster, Silver Garden with Swiss willow and 'Mint Julep' intermediate juniper.
