There were several notable answers and one, from the UK's Green Roof expert, Dusty Gedge, was something to the effect of - 'Both'!
I agree. A Green Roof should look nice and full on install for many reasons, including:
- Jump starts biodiversity support
- Creates visual beauty
- Mature plants clean more stormwater
- Cleans the air
- Quickly sequesters Carbon
- & Much More!
|Green Roof supports biodiversity, cleans stormwater|
Plant mature green roof plants across the roof and fill in the gaps with the plugs. Spread the wildflower seeds across the roof area you wish to grow in as a prairie or wildflower meadow.
Most wildflower seed mixtures contain enough varieties so you can easily meet the 10-20-30 rule for biodiversity, and usually contain tough, hardy plants such as members of the Asteraceae and Poaceae families.
Once established, both the annual and perennial wildflowers will reseed and continue to fill in the rooftop areas.
Utilizing mature plants, plugs and seeds offers a three dimensional quality to the green roof planting plan, one providing beauty over time, habitat support and environmental benefits.