Kohleria humidity problem

I bought some Kohleria rhizomes a while back, they have all sprouted, but some are doing better than others. It seems that some of them are going dry and crispy at the bottom. The picture shows the lower leaves going brown and crisp.


I am thinking it has to be a humidity problem, as the couple I put under humidity domes seem to be doing much better than the ones that are not under my dome. I was under the assumption that they grew in much the same conditions as their cousin, the AV, but I am finding with a higher humidity, they grow much nicer.


The picture below is of some Kohleria Texas Rainbow. It was having some really problems until it went under the dome, and now it is starting to look really good. The ones under the dome are not getting the crispy brown leaves like the others, so I think I am going to have to move all of them into the dome. I have to be really careful as to what I out under the humidity domes, because I have found that plants that don't require such high humidity rot quite quickly.