Seaside roof garden, Dalkey

This was a garden which we created when the architects building this new house got in touch with us and asked for our input. The house, by de Blacam and Meagher architects, went on to win a number of prestigeous architectureal awards, as is quite literally built overhanging the sea. The builder had installed a grass lawn on the roof of the house, which is at road leel and very visible to passers-by. With only a few inches of soil, our plan was to create something like an artificial pebble beach, complete with stones ranging in size from sand to small boulders, and plants which would thrive in this very particular environment.

Not wanting to use chemical herbicides, we covered the entire lawn with biodegradable black paper mulch weighed down with a one to two inch layer of Wexford beach pebbles and shells - from a glacial deposit rather than a beach. This killed off the grass, and after four to five weeks we planted straight into this. We have monitored and maintained this garden now since it was installed. Most of the work involves selective and judicious weeding, as well as occasionally adding a new plant to see how it copes in this exceptionally harsh environment. 

When construction was completed, the builder installed a lawn. Given the need for vents in the roof, as well as the very shallow soil and the proximity to the sea, this seemed like a very uninspiring 'garden'.

A few months after installing the 'beach' garden, plants are starting to fill in. A small area of the garden had soil of a reasonable depth, into which trees and shrubs could be planted. We chose a mix of the highly unusual, such as Pseudopanax ferox and Aeoniums with the more tried and tested seaside plants such as Pinus sylvestris. 

Convolvulus cneorum thrived in the shallow soil and gravel mulch, but died after two years when hit by severe salt-laden east winds in March.

Euphorbia wulfenii subsp. chariacas has thrived and is readily self-sowing. It appears to be immune to the very salty and often cold winds and several years on is growing very well.

Another plant which thrives in the shallow soil is Euphorbia myrsinites - an ideal seaside plant which covers rocks and spills over walls.

The sand and pebbles make an ideal seedbed, so most of our work is 'intelligent intervention' which involves selectively weeding out invaders (grass, dandelion etc) as well as plants which have self-sown with too much abandon: Armeria maritima, Eryngium spp., Verbena bonariensis and Sisyrinchium.

Verbena bonariensis, Agapanthus (white).

More weeding: the flower of Libertia periginans.

Libertia peregrinans, Agapathus (white).

July 2009