agapanthus query

Hello GC people.
I have an agapanthus, it's about five years old, maybe more. It's an evergreen, flowered twice only with lovely pale blue flowers.
It's in a glazed blue pot and really needs repotting.
First, what type of soil is best for the plant? I have read conflicting advice... some say it's an acid loving plant, others say any good garden soil,so I'm confused!
Second, is it true that constricting the plant encourages flowering, or is that a myth and maybe a bit cruel?
Third, it's quite a big plant, should I to divide it to make new plants, or should I keep it in one piece in order to help it flower again this year?

Thank you in advance for your help.

 

@pattie If you are going to repot it I would use John Innes No 3 or this mixed with garden soil. I grow agapanthus and have several growing in the ground. My soil is about neutral maybe slightly on the acid side, but I wouldn't worry too much.
Personally I don't think being pot bound helps flowering.
I split one of mine in autumn 2019 into three pieces one was replanted after the soil had been refreshed the other two given away. The two given away flowered summer 2020 mine took the year off. I just used a sharp spade to split it.
Depending on the shape of the glazed pot you may not be able to extricate without breaking the pot unfortunately.

 

I've never been a fan of the theory that potbound plants flower better than ones that aren't.
It might encourage earlier flowering, but not necessarily good flowering.

Agree with Nigel regarding compost and would suggest feeding with high potash feed during the summer, even if not flowering as that should get it to flower the following year.

If its possible I wouldn't divide it, but that mostly depends on how big it is, as I'm guessing being an evergreen type it needs winter protection.

 

I don't think soil type is too much of an issue with agapanthus, I'm on chalk with no issues. I have a couple of different varieties but no idea of the names, they are evergreen in all but the severest winters, but come back from the roots. In a pot, if they become overrooted, you naturally wouldn't get as much water being kept in the soil, because there is less soil and more roots! I haven't noticed more flowers on pot bound plants, just plants that dry out too quickly

 

Thank you all so much. I have John Innes and my own garden compost, so I'm good to go!
I fully expect the pot to break, unfortunately but a happy plant is the main thing.

 

Ha, ok, I am preening because the agapanthus, with some extra muscle (not mine) has been lifted out of its prison which is the glazed pot and repotted. The glazed pot remains in tact!
The bad news is that the large, deep wooden container to which it was placed fell apart because it's bottom is rotten. I managed to shove it against the wall, whereby it will stay for a while until the plant tells me it has had enough of all this shilly-shallying.
I am a cruel and heartless plantswoman!