Bottled water around palms.

[Delboy]

Would using something much bigger than a bottle help?

How about something fairly big like a bin? I have a 3ft tall black plastic bin with a lid, if i filled this with water (warm?) then put the lid on it and placed it in the middle of my greenhouse would it do anything?

I can see how something like bottles of warm water would work in theory, but changing them over would be a pain in the @ss.

I work 12 hr shifts, both days and nights so messing around outside in the freezing cold after a 12 hr night shift is not something i fancy doing too often.
My Dicksonia antarctica,Trachycarpus and cordy will all be fleeced soon, Trachycarpus & cordy will get a wig wam Dicksonia antarctica will get a lot more protection.

My greenhouse is unheated as i dont have electric down there yet, next year it should be sorted but this year i have bubble wrap on order and lots of fleece....i dont have anything too tender in there tbh but if we get a bad one like last year i know im gonna loose stuff.

Anything that is gonna help keeping the temp up (even a little) will be a big bonus.

[Conifers]

Would using something much bigger than a bottle help?

How about something fairly big like a bin? I have a 3ft tall black plastic bin with a lid, if i filled this with water (warm?) then put the lid on it and placed it in the middle of my greenhouse would it do anything?

Yep, that should work. Any ice that forms in it on cold nights, break it up and discard it outside, then top up the lost water from a hot kettle.