For plants that like extra humidity (like the Fittonia), I sit the smaller plastic nursery pot inside another container with pebbles, to which I add a little bit of water. As the water evaporates, it helps raise the humidity around the plants. I just took these two photos of the Fittonia; you can see the moist pebbles beneath the plastic nursery pot.
Re: My Terrariums, Oh No ... they are not filled with water. Are you perhaps confusing Terrariums (enclosed glass containers with soil and plants) with Aquariums (enclosed glass containers with aquatic plants and fish)? My photos may look like they have water but it's only soil. I know that many people enjoy growing aquatic plants with Betta fish in glass containers but although we have a 250 gal marine (salt water) aquarium in our home, I've never grown any plants submerged in water but I do root cuttings by submerging a small part of a plant stem in a cup of water.
When I first got interested in planting terrariums in the early 1970's, I did use a layer of charcoal between the pebbles and the soil but I haven't used charcoal in many years. I place a layer of pebbles at the very bottom of the container, then add the potting soil and the plants.
Terrariums can be a bit of a learning experience and success is sometimes only achieved through trial and error. Learning a proper watering routine for a terrarium is important, because you don't want the soil getting too soggy since there is no drainage and if the terrarium container has a lid, it's important to remove it every so often so that air can circulate and too much humidity doesn't build up, which would cause excessive moisture and issues with root rot. It's also important to remember to keep glass terrariums a little distance from a window where the direct sunlight on the glass can cause excessive heat build up and damage to the plants.
The photos in my earlier post were taken a few years ago, I don't currently have any terrariums planted up, with the exception of the old one (shown below) that's out on my back porch and I keep forgetting it's there! I've been meaning to clean it out and replant it for the past 3 years but I keep getting sidetracked with other things and still haven't done it! It's an old aquarium that my nephew had when he was in college (more than 20 years ago). He first used it as a home for a pet snake and then he had it for awhile with fresh water fish but after college he was so busy with life and then marriage and family and it sat in his parents garage for ten years and when they decided to clean the garage and asked him if he wanted to keep it. He's been living in California for about 12 years now so he didn't want to ship it out there and told them to throw it away. When I was at his parents house one day and they said it was going out to the trash, I told them I'd take it to use for a terrarium so his dad loaded it into my car and I brought it home and planted it up! It's been sitting out on the porch for 8 months and before that it was inside the house in a corner for about 6 months, neglected and need of a good cleaning for far too long! I removed some smaller plants almost a year ago and I really need to get the Aglaonema out of there to a pot of it's own. My plan is to completely empty the tank and give it a thorough cleaning before starting over. I just went out and took this picture and I see a small Fittonia that I stuck in there months ago to root that I'd forgotten about; there's also a Dracaena marginata from a cutting when I pruned a plant a few weeks ago and I gave it a little tug and it's tight so I know it now has roots ... something else that needs potting.
I'm almost embarrassed to show this picture because the terrarium looks so bad:
This is a photo of the same terrarium from a few years ago:
are you suggesting to move it to a brighter place instead ?
