The flowers do change to pink as the grow older so I imagine this is what is happening. Tea bags won't have any effect on flower colour.

H. paniculata flowers are not affected by soil conditions, colour wise, unlike H. macrophylla types.

Is this a new shrub or is it a old one that has never does this before? If new, could it be a different variety such as 'Vanilla Fraise' or 'Pinky Winky'? Sometimes shrubs can be unstable and throw up something unexpected.

Hi Jimmy ah limelight produces green/white flowers that fade to pink.

Thank you for your replies, most appreciated! This is a new shrub which I only purchased last year from Bents Garden Centre in Cheshire. I'm very disappointed it's turned a dirty pink colour (it didn't do this last year) as I bought it for it's beautiful green/white flowerheads. Is this the pattern of limelight? it's flowers start out green/white and turn pink as the season progresses? Thank you.

I repeat Ruth all limelight produce green/white flowers to start with as they die off they become a dirty pink before going brown.