Comparison of most common extensive green roof planting methods Comparison of most common extensive green roof planting methods

Comparison of most common extensive green roof planting methods
Link to this table

Planting method	Description	Survival rate	Installation labor	Maintenance requirements	Expense	Establishment time	other pros, cons, notes
Plugs	Plants in small pots	High	Medium	Low	Low-medium	Quick, 1-2 years depending on species, plug size, and initial planting density	Allows for most flexible and controlled planting design; can be added to green roofs started from cuttings or to pre-grown mats to increase species diversity
Cuttings	Small pieces of sedums that are spread across or mixed into growing medium	Good	Low	Low	Low - More than plugs, less than seed	Quick, 1-2 years	Less control over final look than with plugs
Seed	Seed	Good	Lowest	Higher	Lowest - Less than plugs or cuttings	Longer than plugs or cuttings – typically 2-5 years depending on species	Less control over final look than with plugs; seed cannot be allowed to dry out until germinated; more bare soil can result in higher weed pressure; need more erosion protection during establishment since soil is bare; only a limited number of species can germinate from seed on a green roof
Pregrown Mats	Plants delivered to the site pre-grown into an erosion control mat with growing medium	Good	Low	Low	Low-Medium	Almost instant green	Instant erosion protection if fully vegetated; precise plant composition difficult to predict; less control over final look; less species diversity possible than with plugs, can be combined with plugs to increase species diversity
Modular Systems	Plastic, metal, or degradable trays filled with growing medium and delivered to site pre-grown	Good initially	Low	High	High	Almost instant green	Allow for greater precision of design, some may require frequent plant replacement due to edge effect; some trays may retain heat and cause soil to dry out faster, negatively affecting plant health