My friend Andy is a construction engineer and thrives on understanding the inner workings of most things. He told me that as a child he was fascinated by an enclosed glass container that held plants and snails. Andy wanted to know how everything living inside was maintained for many years without any human intervention. After listening to his story (over a couple of Manhattans), I decided to create a terrarium for him as a gift. Since I had never successfully created one before, I turned to a gardener friend and terrarium expert, Christie Nohle, to help me. Turns out, it’s not that difficult – you just need the proper materials and planting know-how.

Terrarium materials

Terrariums don’t cost a lot of money to make and only require a few simple materials.

Photo Credit: Mark A. Miller

Terrarium plants

There are many wonderful plants to choose from that prefer the high humidity of terrariums, including Pilea cadierei (center) and the pink-spotted Hypoestes.

Photo Credit: Mark A. Miller

Andy's terrrarium

My finished terrarium made the perfect gift for my friend Andy.

Photo Credit: Mark A. Miller

Terrarium close up

Adding a simple decorative stone to your planting brings an extra-special terrarium touch.

Photo Credit: Mark A. Miller

Terrarium 5-years later.

The terrarium is still going strong five years after making it. Some plant pruning was required.

Photo Credit: Mark A. Miller

Here are the keys – and easy steps – to planting a beautiful terrarium:

  1. The container you pick must be large enough to accommodate growing plants above the potting mix and not create a crammed environment. It can be frosted or tinted, just always keep in mind the amount of light the plants inside the container will receive. (Remember that you want to be able to see your plants, too!)
  2. Place a 1-inch-thick layer of aquarium gravel or small rocks in the bottom of the container. (Colored or decorative stones can be used if you’d like.)
  3. Add a sprinkled layer of activated carbon or charcoal on top of the gravel. (Note: This should be a “handful sprinkle” and not a thick layer.) The charcoal acts to purify the water in your terrarium – much like the charcoal in many water filters. You can find activated carbon or charcoal at pet stores that carry fish tank supplies or at any store that sells aquariums. (I found mine at Walmart.)
  4. Place a layer of unmilled sphagnum moss over the gravel and charcoal to act as a filter between the potting mix and the rocky bottom of your terrarium. This layer should be tamped down to completely cover the gravel – but don’t lay it on too thick. (About an inch or less should work – you want just enough to cover the gravel.)
  5. Add the potting soil or soil mixture of your choice, taking into consideration the mix requirements of your plants. (It’s always best to use a potting mix rather than heavy and possibly disease-laden garden soil. I added a 3-inch-deep layer of potting mix to my terrarium, allowing enough room in the large container for plant growth.)
  6. Place your plants into the potting mix and lightly press or tamp them in so they’re secure. (You should choose small, slow-growing plants that prefer high humidity and don’t require constant pruning. I chose a prayer plant (Maranta leuconeura), a brake fern (Pteris), a maidenhair fern (Adiantum) and an aluminum plant (Pilea) for my terrarium.
  7. Finally, gently pour some distilled water into your container, allowing some to trickle down the inner sides to wash down any lingering potting mix. You should see the water in the bottom of the container amongst the gravel, but it shouldn’t go above the gravel layer. (An inch of water was needed in my planting case.) Put the lid on top, and that’s it! (Let the wonders of condensation do the rest!)

Most terrariums should receive bright indirect light in its final spot – near a north or east window and slightly further away from sunny windows. If you have plants in your terrarium that require full sun, such as Venus flytraps, then place it where it will receive the most sunlight possible.

This simple, affordable container project is as beautiful as it is easy to create. It makes a wonderful gift, as well as brings life and interest to just about any room’s décor. Andy was thrilled to receive his terrarium; it sits in a place of honor on an antique sideboard in his dining room. (Now I just need to create one for his wife, Jayne!)