A tray of wet pebbles ("If the air is dry, mist the plant every morning or stand the pot on a tray of wet pebbles")

[Aridane]

So the standing the pot of a tray of wet pebbles

does that only work is the pot has a drainage hole on the bottom?

Not really, it's supposed to aid humidity around the plant from the evaporation of water in the pebble tray. The pot should stand above the water level so as not to saturate the plant. I'm not sure how effective this really is, but it's worth trying out. Misting regularly will also help, but needs to be done quite often.

Thank you - you are like plant Ask Jeeves source of knowledge!

You don't have to fanny around with wet pebbles, just put a small dish of water beside the plant.

How much air humidity does the plant need - what is it?

It's a Cordyline fruticosa 'Kiwi'

(like this one www.crocus.co.uk/plants/_/cordyline-fruticosa-kiwi/classid.2000032014/)

Cordylines are reasonably tough, but this one does have rather "soft" leaves. I don't think it needs a LOT of humidity, but the leaf edges might brown a bit in a dry atmosphere.

(Thanks for your appreciation! I've been growing plants indoor and outdoor for many years!)