Best first establish what you mean by Arum lily - this name is often used as the common name for Zantedeschia varieties. If that's what you have (google to check), and if it has spotted leaves and the flowers are any colour other than white, it will need to be brought indoors over winter. If, though, its leaves are plain green and it has tall white flowers, it might be Z. aetheopica 'Crowborough' which is hardy outside all winter.

I was about to ask the same question,Bamboo..thanks for that...mine is a spotted one..and it says it isn't hardy..Should I leave it in the pot,under cover,or take it out to store it please ?

You can take them out, dry them off and store over winter in a cool place in a bag or something, but the other option is to bring it into the house and keep as a houseplant over winter, Bloomer.

Hi, I would be interested to know if my arum lilies which are in pots (they are the green leaves and white flower variety) can be left outside or can I put the pots in my garage, I was wondering if the garage may be to dark for them, thanks.

Thanks Bamboo,that is very helpful.I might bring it inside as a house plant .I didn't know I could do that.could you tell me how I look after it please,do I keep it on the dry side, keep it damp,or well watered ?

Depends whether you want it to continue to grow, Bloomer - these plants don't like to dry out completely, so you've no choice other than to water fairly regularly, but let the surface compost be dry to the touch before you do water. Keep away from heat sources such as radiators, tvs, etc, brightly lit spot, don't leave on a windowsill overnight with the curtains drawn so that the plant is in the gap between window and curtain - its too cold a spot for them, but okay if the curtains aren't drawn.

Thanks,Bamboo,..I will more or less treat it like my other house plants in winter then..so no problem there...that is if I don't decide to dry it out instead,but at least I have an option..