Weather can be one of the most deciding factors on which plants work best in an outdoor roof setting. Soil beds are very exposed to the wind, and receive all-day sun with little or no shade. As a result, evapotranspiration is high, and plots can dry out quickly. Storms or little rainfall can also adversely affect plants.
Research indicates that Australian Natives do well, often better than introduced succulents, when furnishing a green roof. Based on such research, Australian company Ozbreed, who grow functional, drought-tolerant plants, has compiled a list of Australian natives they recommend for successful green roof planting.
The following list is recommended for green roof applications in Sydney:
Shara™ Lomandra fluvialtilis | A tough fine leaf compact form with blue grey tones and masses of yellow flowers that sit above the foliage. Tolerates humid climates and suits a wide variety of soils. Best positioned in full sun to moderate shade. Drought and very cold tolerant and can tolerate periodic wet feet.
Themeda australis ‘Mingo’ | A blue prostrate form of Kangaroo grass with blue foliage with rusty red/brown seed heads over summer. Best positioned in full sun to part shade. ‘Mingo’ suits a wide variety of soils. Tolerates frost and drought.
Mundi™ Westringia fruticosa | A beautiful ground cover that if left unpruned will still retain a tidy form, Low growing plant that produces masses of white flowers. Best positioned in full sun to part shade. Suits sandy to well drained clay soils. Tolerates cold and drought.
Yareena™ Myoporum parvifolium | A longer lived form with crisp clean foliage that is frost resistant and very drought tolerant and masses of white flowers. Best positioned in full sun to part shade in sandy to heavy clay soils.
Tanika® Lomandra longifolia | Has been performing in landscapes across Australia for over a decade. It is soft to touch, evergreen, with a compact fine leaf form. Best positioned in full sun to moderate shade. Tolerates frost and drought. Suits sandy, sandy loam to clay soils. Avoid wet feet.
Double Gold™ Gazania hybrid | a fast establishing spreading ground cover with clean foliage and beautiful yellow flowers that appear for most of the year. It is sterile so will not produce any seed. Best positioned in full sun. Tolerates frost and drought. Tolerates free draining to heavy clay soils.
Green John™ Callistemon viminalis | A beautiful lighter green new foliage that contrasts with darker green mature foliage, its green foliage also contrasts well with its red flowers that appear from September to November. Best positioned in full sun to part shade. Suits sandy to well drained soils. Tolerates drought and cold.
Grey Box™ Westringia fruticosa | Has a very tidy natural ball shape when left unpruned and provides great colour contrast with grey foliage and white flowers from September to May. Best positioned in full sun to light shade. Suits most soil types. Tolerates frost and drought. Previously awarded NGIA Plant of the Year 2015.
Lucia™ Dianella caerulea | Deep green foliage with mulberry flower buds in spring that then open into purple flowers that sit high above the foliage, followed by purple berries in summer. Grows well in coastal and inland climates, may discolour in winter in very cold climates, but handles frosts down to -7°c with minor leaf burn. Best positioned in full sun to part shade. Tolerates drought and frost. Lucia™ Dianella suits sandy loam to clay soils. Avoid very poor soils.
Aussie Rambler™ Carpobrotus glaucescens | A prostrate creeping succulent that has long trailing stems up to 2m. It produces extra-large deep pink flowers in spring and autumn. Great for rockeries, mass plantings, a sand dune stabiliser or for any low maintenance gardens in inland and coastal positions. Best positioned in full sun to light shade. Suits most soil types. Tolerates frost, drought, humidity and salt. Avoid prolonged wet feet.
As each region of Australia has individual climatic conditions, different recommendations for various regions have been made by Ozbreed to ensure comprehensive coverage. To find out which plants will work best in your region of Australia visit CLICK HERE
Images (top to bottom): Eco House Forest Lodge; Shara™ Lomandra fluviatilis/Themeda australis ‘Mingo‘/Mundi™ Westringia fruticose/Yareena™ Myoporum parvifolium; Tanika® Lomandra longifolia/Double Gold™ Gazania hybrid/Grey Box™ Westringia fruticosa/Aussie Rambler™ Carpobrotus glaucescens.