The 'fluorescent tubes' might be a hint - marantas don't like high light, and in fact close up their leaves at night and maybe the fluors. were too bright for it. Either that, or you might have spider mites in your enclosure.

Lucy, I agree and disagree..(S) It's true, maranta's dislike scorching sun, but I would have to say too much light pertains to a west or south window in summer. If anything, if Sak's bulbs emit too much heat, (artificial) that 'may' be a problem..Like most other tropicals, warmth is necessary, but when it comes to artificial heat that's a different ballgame.
I find Marantas and their relatives, need humidity, (some more than others) but they also need air circulation.
Also, constantly wet soil is a no-no. As are large containers.
Humidity, (humidifers/misting/trays,) fresh air, medium light, and cozy containers help a lot..I lost one variegated maranta this winter..after unpotting I discovered the pot was too large for its small roots..Thankfully, I divided this plant last year..Toni

Fluorescents don't give off extra heat. Only if a plant were to actually touch the bulb would there be any of that, and not much in any case.

The happiest marantas I've seen are not in terrariums, but in offices several feet from windows with no supplemental light. They have an ability to adjust to where they are, and I've seen survivors from Get Well living bouquets go on to form 14-inch wide mounds sitting on top of file cabinets. I would not use terrarium space for one unless you wanted a sprig for its color and form. Set it free, and grow little ferns and such in the terrarium.

Here is a link that might be useful: my website

Lucy, you're right..the long fluorescents don't throw off heat...did you ever see shorter, swirl-fluoresent bulbs? We use them around the house..there's one above my head,.it's 25 watts but puts out the light of a standard 150 watt bulb..this type of fluorescent gets warm to hot..In other words, I wouldn't want to keep my hand on it..unless a plant is actually making contact with the bulb, there shouldn't be any problems.
I have a couple Calatheas, (relative of Maranta) (common-name: Zebra) growing in an open 30 gallon aquarium/terrarium which do well, but don't know how they'd do if the aquarium was sealed since I feel Calatheas need fresh, circulating air.
According to www.desert-tropicals.com a Maranta leuconeura does fine in a terrarium.. Toni

Just another thing to consider: water quality is important with these plants. They don't like flouridated city water, and even well water has it's problems. When I started using purified drinking water (comes in gallon jugs at the supermarket) is when my marantas and calatheas really took off.

Hi guys,

After reading your posts, I believe it to be a combination of things. The two biggest are overpotting and the soil being too wet. I popped it out of it's pot and saw only a couple teensie rooots peeking through at the bottom, so that's one. And whenever I go to water it seems as though the soil is always still moist. The plant has not come back and I'm not sure at this late date repotting will be helpful. Might just make it permanently croak. I did just recently get some more moisture back into the tank, although the fan is still off. Now that I think about it, the plant was healthiest when I had the gravel trays wet and the fan going in the terrarium. Usually the humidity in there would get to around 75-80... but I agree, I think it could come out of there and my future nepenthes could go it in instead. (Current ones are doing fine, btw - I have no problem there! lol)

So, I may have to find someone with a cutting or buy a new plant since I'm not positive this one will make it. New growth has stopped and only two leaves are unfurled. The rest are curled up and almost totally brown now. Should I bother ropotting? If I had some more time, I'd post a pic. Maybe when I get back from errands later today.

Thanks everyone for your help! (By the way, I did move it a few inches further away from the bulbs, but it never gets very warm in there.)