Deconstructing the Agapanthus Cafe!

With the cold weather just around the corner, we've moved the pots of Agapanthus from the informal seating area (aka The Agapanthus Cafe!) beside the pond into the Greenhouse for the winter.
We have the evergreen Agapanthus, which are rather more tender than the deciduous varieties. We have a mixture of A. africanus that arrived as washed cuttings around 15 years ago (not something I would do now) from Madeira, and A. Headbourne Hybrids which we grew from seed.
We overwinter the plants in our unheated greenhouse here. They can survive a couple of degrees of frost but too cold and the leaves go opaque and then yellow. We've had this happen - fortunately the plants survived, but I would want to avoid this happening where possible.
Before we put them in the Greenhouse, we took the opportunity of removing decaying leaves as well as cutting back the old flower stems, checking for dormant slugs at the same time!
Come late February, when the sun's rays really start to heat the greenhouse, we shall step up the watering and begin feeding with a high potash feed to force the flower buds. These will start to emerge in April/early May whereupon the plants will return to their summer residence. It's always an exciting time when you see the first bud emerge, and when they do, they shoot up quite fast!
We grow our plants in terracotta pots in John Innes 3 with a good lot of added grit. So far, we've only repotted them when their root mass splits the pot, which happens spontaneously from time to time. They really are strong enough to do this.
The old books say that Agapanthus only flower well if their roots are tightly packed in pots, but recent research has found this to be a bit of a gardener's tale, and certainly we've found that transplants from the previous year do flower the following year. But this is probably down to the potash fertiliser building the buds the previous year.
As some of our plants are starting to produce fewer buds, we'll start a programme of dividing and repotting them each Spring for the next 3 years or so. As an experiment, we're going to try growing some tucked in against one of our south-facing walls to see how they fare.