Crassula alba
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 alba is found growing on and amongst rocks in grassland in full sun in the Durban area.

Growth habit
Crassula alba is rosette forming succulent that produces a tall flat topped flower head.

Propagation
Crassula alba reproduce naturally by means of seed. In cultivation this plant is best propagated from seed, large clumps can also be subdivided.

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

Drought resistance
These plants are very drought resistant.

Disease and pest resistance
They are susceptible to attack by two species of Lycaenidae Butterfly the Common Black Eye  Gonatomyrina gorgias gorgias and the Tailed Black Eye Leptomyrina hirundo which use them as larval host plants.

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. Crassula alba reproduces it's self freely from seed.

Biodiversity value in the Green Roof landscape
Their profusion of small red flowers which are produced in a large flower head have an extensive flowering period attracting 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.