So you've followed every direction and built the perfectly planned terrarium! You washed your moss, quarantined your plants before planting them and used only the freshest bagged potting soil and sphagnum moss for your soil layers. You've been cautiously watering your terrarium and are keeping it lidded for 75% of the time. And yet- the terrarium fails! Mold appears, plants die or the whole thing becomes a disgusting swamp or dried out wasteland.
I've been there more times than I can count and trust me- it is a sad truth of the terrarium hobby. You've got to know when to fold and just restart a terrarium.
- First you'll want to dump out your terrarium vessel and wash it out well (with warm water and perhaps a drop of bleach). Be sure to let it dry completely before replanting to avoid getting dirt etc. stuck to the sides of the glass.
- Re-evaluate your terrarium vessel. Is it a very narrow test tube that barely allows any air circulation inside the vessel? A giant cylinder that is completely open at the top and might as well be a traditional ceramic pot? Your plants need to match the vessel. Humidity-loving or tropical plants need to be in a container that has a narrow opening or in a vessel that is partially or fully lidded for most of the time. Succulents and more typical plants do better in open top vessels.
- Did you wash your moss and quarantine your plants the first time around? If not, proceed back to the start and do not collect $200 dollars. Get some new plants and moss and start again.
- Did you over water your terrarium? A terrarium can easily go a week or two without water once it has been established. A few spritzes or drops of water is all it takes to keep it happy.
- Consider the environmental needs of your terrarium. Was it in a windowsill getting full sun for several hours a day? In a dark room with nary a window or fluorescent light in sight? Most terrariums do best in filtered light (adjacent to a curtained window) but you'll need to experiment to find the optimal location.