Crassula expansa
Is one of a number of plant species which are presently being tested for their suitability to be grown as Green Roof plants in the Durban region that have initially shown good results. They all occur naturally within a radius of 50 km of the Durban city centre

Crassula expansa is found growing amongst rocks both in shade or semi-shade in a number of localities in the Durban area.

Growth habit
Crassula expansa is a dwarf mat forming succulent.

Propagation
Crassula expansa reproduce naturally by means of seed and vegetatively. In cultivation this plant can be propagated vegetatively by either planting cuttings of simply by breaking up the plant into tiny pieces which are then scattered onto the growing medium which must be given protection from the sun and watered until they have rooted.

Decorative value
These plants are being grown for their very attractive growth form as well as their multitude of small white flowers.

Drought resistance
These plants are surprisingly drought resistant which is surprising as they usually grow in shade or semi shaded localities which are rather damp.

Disease and pest resistance
They are susceptible to attack by mealy bug.

Suitability as Green Roof plants
These plants are valuable ground covers because of their dwarf growth habit, the ease with which they establish themselves and their rapid growth habit. Under green roof conditions they have displayed extreme heat and drought tolerance and the ability to grow in very shallow dry soils. 

Biodiversity value in the Green Roof landscape
There profusion of small white flowers which are produces over an extensive period of time attract large numbers of insects in particular the honey bee.

Cautions and precautions in the Green Roof application
Care must be taken to ensure good drainage to prevent rotting during establishment.