How to use Fleece?

We have 2 plants in our garden that do not like it really cold - the rest are all hardy. The two are an Arum lily and a Japanese money tree (yes I know it is supposed to be a houseplant but it got put outside when it got too big and it has thrived). Last year the lily was fine except for one really cold night when it just collapsed and the money tree died on one side but recovered in the spring.

I have bought some horticultural fleece and put in on them but I dont know if I am supposed to leave it on all winter or take it off during the day or what.

Please help! Thanks for any advice

 

all winter

 

I use an old blanket, fleece I find isn't enough on really cold nights, and remove it every day if the temperature is above freezing. Fleece is good for those spring frosts that we get when the temperature drops just for a couple of hours or so.