A couple of other options if you want to increase humidity. Cypress mulch holds moisture really well, it's hard to find this time of year though. It's usually used for landscaping and can be found everywhere in the spring but is usually sold out by now. You might still be able to find some in garden supply stores. Orchid bark also holds moisture very well. This is basically fur bark but it's ground to a finer size so it's easier to work with and I think it looks better. It is a bit more expensive though. Whatever you use, just make sure it contains no ceder or colored dyes.