Growing divisions when bank is involved in financial transactions (9)

'growing divisions' is the definition.
(divisions grown in a garden)

'bank is involved in financial transactions' is the wordplay.
'bank' becomes 'row' (I've seen this in other clues).
'is involved in' means one lot of letters goes inside another.
'financial transactions' becomes 'hedges' (as in hedge funds).
'row' inserted inside 'hedges' is 'HEDGEROWS'.

'when' acts as a link.