I've made three terrariums.
  1. This is the smallest. The jar is a little bigger than a pint, but barely. It's probably too full.
    This one is about a month old.
  2. This one is a little bigger than a quart. These two smaller one sit side by side on a window sill in my library. This may have too much water. Time will tell.
    This is also about a month old.
  3. This is a gallon jar.
    This one is a little over two years old.
  4. So far I haven't opened any of them since first making them. I don't plan to unless all of the plants die. The big one had an African Violet that died, but I haven't taken it out and don't plan to. It can decompose and become fertilizer.
  5. I've read of people having sealed terrariums for over thirty years successfully. I had a five gallon glass water bottle terrarium that lasted maybe 3 years once, but I moved it, and it didn't get enough light and I didn't realize that until everything was dead. Oops.
  6. I decided that there was too much moisture in the medium sized one, so I took the lid off for a couple of days and this happened. I stuffed it all back in there and popped the lid back on. We'll see what happens.