Would probably be happier planted in the ground given that they like semi shade and damp conditions.

Lack of water and/or nutrients will stop bloom on an arum lily, as Moon_grower says. One thing you can do, if it isn't 'Crowborough', which is the only hardy one, is to plant the pot in the ground, and allow the roots to grow through the drainage holes. That will allow the plant to have some of the benefits of in the ground growing, yet still make it easier to dig it up and store it when frost threatens.