About 8 years ago I planted in my garden in Guildford, England, 24 mixed blue and white Agapanthus. Over the years they have "reverted" to white with only 3 blue flowers remaining. This seems quite extraordinary given that the natural colour of the plant is blue. They abound naturally in the Scilly Isles and rarely does one see a white one. Our sub-soil is chalk with layers of compost. Has anyone any ideas as to why this phenomenon occurs?
Your white ones have, in fact reverted to typical blue or have died and been replaced by blue seedlings. I once had one white and one pink hardy cyclamen growing by the back door, two clearly separated specimens with no seedlings having grown up to reach the same size. One year the white one bloomed pink and remained so subsequently.
Ron, My query was the reverse to your answer! Most of the blue Aggies have changed to white so I think there must be a lack, or too much, of something in the soil. It is a mystery as I have been in touch with RHS Wisley and also the excellent plant nursery where I bought the plants from. Thanks for your reply, Gillocks