 |
| Sean Hogan experiencing some high country natural green roof plants in New Zealand on his recent tour here. |
An enthralling talk to Balclutha Garden Club in mid May by Sean Hogan from Portland, Oregan in North America enlightened about 30 people about green roofs or eco roofs .
This is not a new
concept but it is exciting to see it being developed on a garage,
house, shed, commercial building, public spaces and even house
trailers, caravans and bus’ roofs. ‘’It is a nice way to
enliven many areas with interesting plants,‘’ Mr Hogan said. ‘’
I have been working on green roofs for a long time and am interested
in their aesthetics as well as their functionality.’’
Coming from Western
Oregon which is quite dry in summer, leading to a water shortage
then, makes it ideal for water conservation methods with green roofs
one way to ensure this happens. Portland city on the coast has an
increasing number of green roofs as they catch the water and release
it slowly, helping it trickle down so easing the pressure on storm
water systems in winter.
Europe has been doing
this for some time but America is developing its own model. Pioneers
and old derelict houses develop green roofs anyway through neglect.
Mr Hogan works for
Cistus Design Nursery in Portland, doing planning, design and
consultation. When designing green roof gardens he mostly uses a
variety of drought loving native plants, specific to the local area.
‘’We can actually
use any plants which are not weeds, poisonous, or cause a rash,’’he
said.’’The plants need to be able to cope in dry conditions
whether that is for a season as it is at home or for a few weeks as
it might be here in New Zealand.’’
 |
| A green wall design with fascinating plants and colours creating an artistic effect. |
People can create green
walls as well.
‘’ This a lot of
fun if you have a blank wall,’’ he said.’’ You put some
layers of mesh on it with soil in between and press succulent plants
in to it to make a collage of colours.’’
They use pumice rich
substrate and organic soils along with legumes to build up nitrogen.
These gardens have to be able to cope with any weather. The green
wall can be any depth up to 15cm, with the roots intertwining and
holding it all together. It can be treated as a piece of art.
Drought resistant
plants which are suitable and survive well in these conditions
include phlox, penstemon, sedum, milkweed, ferns, bulbs, orchids,
bulbinella, trillium, epilobium, lewisia, agave, delphinium, salvia,
carex, hebe, astelia, iris and yucca.
Succulents and ice
plants are excellent as they need very little soil and don’t dry
out.
Mr Hogan reminded the
audience that the nearest green roof is at the Otago University
Psychology building, all planted up with natives. This is an
excellent local example of how effective these roofs can be, with
visitors welcome by appointment.
‘’I do general
garden design but my particular passion is in encouraging people to
do green roofs,’’ he said.’’One of the significant green roof
buildings is M Financial Building in Portland which covers almost a
30m by 30m city block, which is quite impressive.’’
 |
M Financial Building
in Portland with an impressive green roof.
|
