holly

[jaffa1]

when should i prune my holly bush

[Thunderbird+]

Now (summer) is a good time to prune it if its a specimen shrub. cut out any green leaves if its a variegated one.
For hedges, spring or summer. Good Luck Tbird+

[heathfield]

As Thunderbird says, mid to late summer, since it'll allow new growth to form before things slow down in winter.