DIY Terrarium

This isn’t just a terrarium.  No.  It’s a problem solver.  What problem does it solve, you ask.  It’s the only way I can seem to keep this dang maidenhair fern alive.  You see, these plants are pretty picky.  They need high consistent humidity, bright light but not direct sun, and rich soil, which they rapidly deplete.  I used to grow this particular plant in  regular glazed pot and it almost died (I thought it was dead but it came back) because it was too close to the breeze that comes out of the heating/cooling vent.  Yeah.  That’s picky.  The terrarium keeps a consistent 70% humidity; I know this because I keep a hygrometer in it.  The scientist in me needs to know.

The terrarium solves another problem too:  What to do with a vase with a crack in the bottom.  This recycled glass vase used to be my fish bowl.  One day, I was sitting near the fish bowl and hear “tink!” sound.  I didn’t think anything of it.  The fish often moved rocks around so I figured it was him.  Then it happened again, louder, and water started pouring on the floor.  Ugh.  Had to save the fish really quickly, then figure out how to get 1 1/2 gallons of water out of the carpet.  I still don’t really know how the crack happened, but it’s about 3 inches long on the corner between the side and the bottom.  The white line on the bottom of the terrarium is the silicone I used to patch it.

So how is this thing put together?  Here’s what I did:

  1. You need: a vase or big jar, gravel, sand, potting soil, a plant that likes humidity, decorations like rocks or a ceramic horse.
  2. Lay down about an inch of gravel, then an inch of sand.  This will help with drainage and provide a reservoir for water to keep the humidity constant.
  3. Add a few inches of potting soil, placing your plant in the soil where you want it.  If the container is big enough, you might be able to fit a couple of plants.
  4. Arrange your ornaments or rocks.  Don’t use anything that can rot.  I tried having some fat sticks in mine that looked like little logs and they molded.  Not pretty.  Stick to things that won’t grow mold.
  5. Water, but not too much.  It needs to be moist, but you don’t want a bunch of water to accumulate in the gravel.  Mine is usually just wet enough to see that the gravel is damp, but no real standing water.

How do I know that this is working?  Well, the fern makes new fronds every time I give it some new potting soil and I can see that some of its roots have grown down through the soil to the bottom of the container where it can always have water, like it would in the riparian areas it naturally grows in.

Are there any problems?  Aside from the mold issue with the sticks, I’ve grown some mushrooms accidentally, but they didn’t cause any problems.  Because the container is glass though, there are some fronds developing under the soil heading for the glass (picture below).  I covered it with black paper hoping they’ll head up instead of out, but I guess I have to wait and see what happens.  It’s an experiment, after all.

About micheletobias

I lead two lives - one as an artist and the other as a scientist. More and more I'm finding my two worlds colliding, and it's not the disaster you might expect. View all posts by micheletobias

7 responses to “DIY Terrarium

  • Kate

    I love terrariums, I just started making a bunch of them this week. I’m no fern expert, but from past experience I’ve found that some plants do better when there’s also a layer of charcoal included below the soil.

    • micheletobias

      I’ve heard that as well. I couldn’t figure out what exactly the charcoal was supposed to do. Do you know? Mine has been going fine without it for about a year now, but maybe it’s just that the plant is so happy to be out of the regular pot.

  • Imported Kiwi

    I like the look of your terrarium. I have one of these ferns, just in a pot. Had it for years and it grows like mad. It hardly needs looking after and even survived when my cat sat on it. Where I live is not humid or hot at all (latitude 43 degrees in New Zealand).

  • Veronika

    Hey! I found your blog after you found mine, and figured I’d say hi! It’s good to see a fellow scientist (I’m not an ecologist, but I am a food biochemist!) blogging about gardening, and other interesting stuff (liked your commentary on the not-as-pretty-as-some garden in the newest post too).

    This terrarium is something like what I would like to make for my next project – only I’d like to get some clumping moss to grow in it (and maybe a tiny local fern too). Do you have any advice regarding open-top terrariums, humidity and centrally heated apartments? Or should I try to go for one of those apothecary jars that pop up in image searches with the lid on?

    • micheletobias

      It’s nice to meet you, Veronika!

      I’ve only tried the one open terrarium. It’s definitely more humid inside than the outside air (I’ve got a hygrometer in there to check). The nice thing about having an open terrarium is that if the plants get too big, they can just grow right out the top. They key thing I’ve found is to keep it away from the air conditioning and heating vents. Figure out where the air blows and make sure the terrarium isn’t in the direct path of the air. I’ve tried to grow some moss in my terrarium, but it hasn’t worked. My water has a lot of salts and I think that’s been the problem.

      • Veronika

        Ah yes. Salts in the water would be a problem for mosses, even more so than for orchids. I guess I am lucky with water – after boiling water for over a year here I am yet to see visible deposits on it, so I can conclude (in absence of any instruments and after reading the water report as well) that it’s just very clean. We’ll see.

        Have you tried filtered and/or boiled or rain water for your terrarium? I haven’t but I imagine the fern would like it as well, and you could try some moss in there if it proves to be not too much work? Or just decided to stay mossless?

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