All my agapanthus come from Hoyland based 'Something for the Garden' and range from small white Double Diamond to the enormous one mentioned before. I also have Tulbaghia and these are the most delicate looking, but I think tough, plant. Look great in a pot but I do take them into cold greenhouse for winter. Anyway hosta fan 1, it is probably the Agapanthus food I feed them on - turning them into Giants. I used to use tomato feed but since using this stuff I have noticed a difference, lots of flower heads on all the agapanthus.
Thanks for all the replies, very helpful. Have found a picture of the type of Agapanthus I am trying to track down. Obviously not one that this gardener will be moving under cover Anyone know what variety this is please?