The agapanthus was first cultivated in the Royal Gardens at Hampton in 1692 - by Victorian times it was an old favourite.
It was generally cultivated in pots or tubs in the garden as most gardeners felt that it required some protection during winters, although in the south of the country it could grow well outdoors all year if protected from severe frosts (although Victorian Manchester boasted a large established clump in the botanical gardens that had been in the border for several years).
The agapanthus required rich loamy soil that needed much watering in summer time.* If grown in pots then they needed to be periodically potted on into larger pots as they became rootbound.
*I felt I had to add a note here: in Australia they are renowned for their drought tolerance, and clumps survive many years with little rain and no additional watering.