Agriculture Reference
In-Depth Information
Fig. 12.8
Roof garden
containing a range of Sedum
pp. (Photograph courtesy of
A. Bettin)
to a particular plant. Reclaimed gardens set up on waste land pose a particular
challenge and may require special amelioration to make them suitable for orna-
mental plants. Another special consideration is roof top gardens where soil depth
is limited, or where containerised plants have been established in shopping malls.
The presence of green space in cities has been found to make important contri-
butions to the sustainable development of urban and peri-urban communities by
improving the environment and contributing to conservation and helping to reduce
global warming, remove pollutants and reducing dust and carbon dioxide, as well
as reduce sound while reducing stress levels of city dwellers (Aldous
2007
). The
inclusion of ornamental vegetables, medicinal and aromatic plants have also been
known to benefit city communities (Arslan and Yanmaz
2010
). Development of
roof top gardens (Fig.
12.8
) requires special attention to be sustainable, choosing
the right plants such as sedum (
Sedum
spp.) to tolerate the more severe condi-
tions as well as species of
Zoysia matrella, Verbena
hybrids,
Thymus vulgaris
and
Targetes
sp. (Sendo et al.
2007
). The sedum species have been known to survive on
shallow substrates on roof top gardens in Germany (Monterusso et al.
2005
).
Environment
The environment plays a crucial part in the growing of ornamental
plants, particularly the right temperature and light conditions suitable for flowering.
For instance, to grow Geraldton wax in Europe would require careful manipulation
of local temperatures to ensure that the plants flower. Alternatively, these plants
could be grown in a warmer climate such as Portugal or Spain then transported to
Northern Europe. Figs.
12.9a
and
b
demonstrate the appropriate internal and exter-
nal temperatures that initiate flower development of Geraldton wax. Production
involves a 16 month life cycle to produce plants of sufficient size and flower cover.
Special case environments
Many landscapes pose a challenging environment for
growing plants. Within a city environment the thermal mass of buildings, roads
and pavements introduces a heat load and with traffic the air can be higher in car-
bon dioxide carbon monoxide, sulphur dioxide and nitrous oxide levels as well as
altered light levels. All these features can affect plant growth and development in
confined areas. In these situations careful design of gardens is needed to cope with
or maximise the benefits of these environments. There are many good examples
of successfully domesticating plants for people in cities where plants can improve
environments that pose a challenge from extreme heat from radiant heating or from
