I will replace those purple Iris with these ones from the Sun Garden.
Purple and white. Perfect transition.
Then I will move these rich purple Iris into the sun garden where they will provide a nice contrast to the the bright sunny colours.
In the middle around the entrance we have purple & white pansies, purple pansies and purple violas in the planters. Then before jumping completely into white purple has a last hurrah with the Allium which are set off so well again the hedge. Under the Allium I have planted seeds for a low-growing white ground cover and then it really is off to the races, all white all the time.
What do you think? I subtle and effective transition?