c/diy-terrarium-builders

Someone told me my moss wall was too wet and now I get it

I posted a pic of my first closed terrarium here a while back, a jar with a little moss wall on the side. A user named 'FernGuru' commented, 'That moss is gonna rot in a week, you're drowning it.' I was annoyed but checked after five days, and sure enough, the moss was turning brown and slimy. I took it out, squeezed most of the water from the sphagnum moss base, and let the jar air out for a day before sealing it again. Now the new growth is bright green and happy. How do you guys judge the right dampness for a sealed setup?

Built two terrariums last weekend, one with gravel and one with leca.

The one with the leca layer at the bottom is way less soggy after five days. The gravel one already has a puddle. Is leca just better for drainage, or did I mess up the gravel setup?

Found something nasty in my sealed jar from 2020

I opened a terrarium I made three years ago in my old apartment in Phoenix, and the whole thing was covered in thick white mold. I used regular potting soil instead of a sterile mix, and the humidity must have baked in that Arizona heat. Has anyone else had a sealed setup go bad after that long, and what do you do with it?

Found out most terrarium failures happen in the first 90 days from a plant shop blog

They said it's usually from overwatering or not enough air flow. Has anyone else had a project crash right around the three month mark?

My sealed jar in Denver got a crazy white mold bloom last month

Honestly, I was setting up a new mossarium in a big glass jar and forgot to let it air out for a few days before sealing it. Tbh, a week later the whole thing was covered in this fuzzy white layer. Has anyone else had this happen and what did you spray or wipe it down with?

Appreciation post: I stopped using charcoal in my closed terrarium layers

For a long time, I followed the common advice to put a thick charcoal layer under the soil to keep things fresh. My setup in a big glass jar from a local shop in Columbus would get cloudy and smell off after about six months. I switched to just using a deeper drainage layer of small stones and skipping the charcoal completely. The plants look healthier now and I haven't had any mold issues. Has anyone else ditched the charcoal and seen better results?

TIL my closed terrariums were basically drowning

I kept losing ferns in my big jar setup and my friend in Portland said, "Claire, you're watering a sealed box." I pulled the cork for a day and everything perked right up. How often do you guys actually open yours?

Tested charcoal chunks vs. activated carbon for drainage, and the results were clear

I saw a terrarium at the Portland garden show that made me question my whole setup

It was in a huge, clear apothecary jar, maybe 5 gallons, but the grower had used a false bottom made from plastic egg crate instead of gravel. They said it kept the water moving better and stopped root rot. I've always used a thick layer of small stones, but now I'm torn. Is the extra work of cutting and fitting the plastic grid worth it for better air flow, or is the classic stone layer just simpler and safer? What's your take on drainage layers?

Overheard a kid at the plant nursery call my terrarium a 'boomer jar'. Got me thinking about how the hobby has changed since I started in 2010.

I used to think you needed a ton of light for moss, but a guy at the Denver Botanic Garden changed my mind

I was setting up a closed jar terrarium last month and asked a staff member about my light setup. He pointed to a huge, healthy moss wall in their greenhouse that only gets indirect morning sun for about two hours a day. He said, 'Most mosses burn easy. Think damp forest floor, not open field.' I moved my jar from a south window to a north-facing shelf, and the moss is way greener after three weeks. How much light do your moss terrariums actually get?

So I tested charcoal vs. moss as a drainage layer in two identical jars

I made two small fern terrariums in the same kind of jar about a month ago. One got a half-inch layer of activated charcoal bits under the soil, the other got the same amount of sphagnum moss. The moss jar started smelling a bit funky after just two weeks, but the charcoal one still looks and smells fresh. I think the charcoal really does a better job keeping things clean. Has anyone else found a clear winner for their drainage setup?

I bought a 'self-watering' terrarium kit and it drowned my whole setup

Saw this fancy kit online for $45 that promised to keep the moisture perfect for a whole month. I set it up with some baby tears and a small fern, following the instructions exactly. The little water reservoir at the bottom just kept soaking the soil, and after about ten days everything was moldy and the plants were mush. I mean, it basically just made a swamp. Has anyone actually had luck with these things, or should I just stick to my spray bottle?

My sister told me my moss wall looked like a sad green sponge

I built a big closed terrarium last month with a vertical moss section, and my sister came over and just said 'It looks like a wet green sponge got stuck to the glass.' She was right. I had packed the sphagnum moss too tight and used only one type. I redid it with three different mosses from a hike near Boulder and left way more air pockets. Has anyone else had a family member give brutally honest feedback that actually improved a build?

Update: I used to just dump my charcoal layer straight in...

Now I put it in a little mesh bag after my third jar got that black dust everywhere. Anyone else find a cleaner way to handle it?

My moss wall kept failing until I switched to a different glue

I used to make moss walls with that white craft glue you get at any store. It worked okay for a few weeks, but then the moss would turn brown and fall off. I lost three projects in a row last spring. A guy at the plant swap in Denver saw my sad jar and told me to try a specific aquarium-safe silicone, the kind for fish tanks. I got a tube for about eight bucks. The difference is huge. You apply a thin layer, press the moss on, and it holds it in place but still lets it breathe. My latest wall in a big pickle jar has been green and happy for over four months now. Has anyone else found a better adhesive for holding live moss in place without killing it?

My 'cool' geometric glass jar from a flea market looked amazing but killed everything inside within a month, unlike my boring old fishbowl from the thrift store that's been thriving for over a year now.

The fancy jar had zero air flow and cooked my mosses, but the simple bowl's wide opening lets just enough moisture escape to keep my tiny fern happy... anyone else have a terrarium vessel that looked great but was secretly a death trap?

I tried both springtails and isopods for my closed terrarium and the results were clear

I built two identical 5-gallon jars with the same plants and soil mix last spring. One got a starter culture of springtails, the other got a few powder blue isopods. After 4 months, the isopod jar had visible plant damage and the soil stayed too wet. The springtail jar had zero mold and the plants thrived. I think people push isopods because they're more interesting to look at, but for a balanced closed system, springtails just do the cleanup job better without becoming a problem. Has anyone else found isopods to be more trouble than they're worth in a sealed setup?

Hot take: Buying a $50 moisture meter was the best thing I did for my closed terrariums

I mean, I used to just guess when to water by looking at the glass, and I lost three whole setups to mold in like six months. I finally got this little probe tool that tells you the exact wetness of the soil. It showed me my substrate was way too damp even when the top looked dry. Now I only water maybe once every two months, and everything stays healthy. Has anyone else found a simple tool that totally fixed a big problem for them?

My five year old asked if the springtails in my jar were 'tiny janitors' and now I can't unsee it.

It completely changed how I explain the cleanup crew to people who think my terrariums are just pretty decorations.

I always used tap water for my closed terrariums and they kept failing

For about a year, every sealed jar I made would get moldy or the moss would turn brown after a month or two. I was using filtered tap water from my kitchen in Atlanta. Then I saw a video where someone mentioned chlorine in city water can kill the good microbes. I switched to distilled water from the grocery store, and my last three builds have been thriving for over six months now. So, is using distilled or rainwater really that big of a deal, or was I just unlucky before? What do you all use?

Showerthought: I fought with springtail cultures for way too long

Took me 3 months to realize my tap water's chlorine was killing them, switched to bottled spring water and they exploded. Anyone know a good brand for dechlorinator drops?

My old terrarium from 3 years ago in my first apartment is still thriving with just the original moss and a few ferns.

Last week I moved it to a new spot with less sun, and it made me realize how much simpler my builds were back then compared to the complex setups I try now.

After 50 terrariums, I still don't add charcoal

I see so many people adding charcoal to their layers. Mine do just fine without it, no smells or mold. Is this step really needed for basic jar gardens?

Ngl, when family calls my terrarium a 'glass box of weeds', it stings. Some say ignore them, others say educate them. Where do you stand?