Stun factory, producing growth (4,5)

I believe the answer is:

rock plant

'growth' is the definition.
(type of plant)

'stun factory' is the wordplay.
'stun' becomes 'rock' (both can mean to shock).
'factory' becomes 'plant' (a manufacturing plant).
'rock'+'plant'='ROCK-PLANT'

'producing' acts as a link.

(Another definition for rock plant that I've seen is " Alpine".)

I've seen this clue in The Times.

Want a hint initially instead of a full solution? Install my app