What should I do if my small fish bowl terrarium gets moldy dirt?

I have a succulent in a small fish bowl terrarium that grew rapidly and outgrew its bowl. I just tried to prune it down and noticed it looks like mold growing in the dirt layer. I get it, I obviously overwatered it. I won't do that in the future. But can I salvage my terrarium or do I just need to toss it? When my house plants got mold in the dirt/fungus gnats- I dumped the dirt, wash the plant and it's roots, wash & sanitize pot then re-pot. Can't do that with a terrarium :( Please help, I don't want fungus gnats to show up and spread to my house plants but I love my succulent terrarium- made it together on a date with my husband- we named it Oscar. Please help me save Oscar.

Thanks- Maura

  3 answers
  • Get an iced tea spoon and carefully remove all the moldy bits. Test the soil before watering next. I stick my finger down into the dirt about 2". If damp, wait a few days. If dry, give a little water.

  • Lynn Sorrell Lynn Sorrell on Feb 16, 2019

    Terrariums don't need watered so much the moisture is usually retained in them thru humidity and plants in it should not even need more than occasionally being misted, leave it open to dry out some,do as Naomi suggested to get mold out, then buy some Nematodes they will control fungus gnats. This company guarantees they are alive https://www.arbico-organics.com/product/nemattack-beneficial-nematodes-sf-steinernema-feltiae you can probably get them cheaper else where but as I said these are alive (you cannot even see them in soil) use them in all house plants. orgnic beneficial bug pest control

  • Maura Q. Steele Maura Q. Steele on Feb 16, 2019

    I just tried to use a small spoon to remove the moldy dirt. Unfortunately it seems the mold is way more prevalent than I originally thought. I think I need to replace the sand and soil layers. Hopefully I can salvage the rest of the terrarium. It'll just be more work.

    Thanks for the tips Naomie Moore and Lynn Sorrell!  I'll check out those Nematodes soon!