Creating a DIY Terrarium

Creating a DIY Terrarium

Looking to liven up a dreary afternoon? Designing and assembling your very own terrarium is the perfect project to exercise your creative muscles and experiment with growing houseplants in a new way. Plus, at the end, you'll have a beautiful finished product to beautify your home! Follow along with this step-by-step tutorial to create the terrarium of your dreams with a little help from Cornell Farm.

Planting a Terrarium

1. Gather your materials. The obvious place to start when setting out to make a terrarium is with a glass container — the vessel that will hold this miniature world of your own creation. Your options vary from large to small and open to enclosed, and these are important factors to consider when selecting the type and number of plants you will start with. If you go the classic route and create a closed terrarium, you should stick to a palette of plants that thrive in environments with high humidity and low air flow, such as Club Mosses, Miniature Ferns, and Peperomias. For this tutorial, we have opted to create an open terrarium, which does require us to pay closer attention to our watering schedule, but offers us access to a wider range of plants in return, in addition to reducing the risk of unwanted mold and fungi. The other factor to consider when choosing a container is the size of the opening, as this will not only limit the scale of your plants and decor, but also the ease with which you will be able to set things up and perform any necessary maintenance down the line.

When selecting plants for a terrarium, keep in mind the "thriller, filler, spiller" mantra often used for designing container gardens outdoors. The scale may be different, but the principle still applies! In our case, we chose a miniature False Aralia as our "thriller," a Bird's Nest Fern as our "filler," and an adorable Pilea glauca as our "spiller." These plants offered us a variety of contrasting textures. colors, and forms, which makes for a visually dynamic arrangement. If your goal is to keep your terrarium going for years, think about the amount of time you are likely to invest in trimming on a regular basis and choose your plants accordingly: Smaller, slower-growing plants are easier to maintain long-term. Of course, while a well-designed terrarium can last for years, there's nothing wrong with changing things up and re-planting a terrarium more often than that, either.

In addition to your choice of container and plants you will need the following materials and tools to get started:

  • Set of Miniature Terrarium Tools or Long-Handled Aquarium Tweezers (Chopsticks can also do in a pinch!)
  • Long-Handled Paintbrush
  • Scissors
  • Spray Bottle
  • Small Pebbles or Aquarium Gravel
  • Horticultural Charcoal
  • Potting Soil
  • Recycled Plastic Bag, Permanent Marker, and Thumb Tack (Alternately, a small section of Window Screen will work.)
  • Rocks, Stones, Pieces of Cork, Small Twigs
  • Preserved Moss
  • Decorative Touches (Fairy Garden Elements, etc.)

2. Create a drainage layer using small pebbles or gravel. You will want to add at least a half-inch of pebbles, though if you have the vertical room, closer to an inch is preferable. In general, the larger your terrarium, the deeper you want this to be. A drainage layer is the foundation of any successful terrarium because it gives excess water someplace to go. Without a drainage layer, this water can quickly saturate the growing medium, which can rot not only your plant's roots, but the soil itself. Yuck! (This is the same reason that plants should be grown in pots with drainage holes.)

3. Create a substrate barrier that will allow water — but not soil — to pass through. Without this layer, your growing medium will have a tendency to migrate down into your drainage layer over time, defeating the purpose of having a drainage layer in the first place. While you can certainly use a fine mesh such as window screen for this purpose, we think this is a great opportunity to reduce, reuse, recycle. A simple plastic sandwich bag that has been used and rinsed will do the trick. Just trace the outline of your container's base onto the plastic using a permanent marker, then, break out the thumb tack! You'll want to poke a good number of holes inside the outline you've just traced, and once you're satisfied that water will be able to drain through the plastic, you can cut out your outline using scissors and lay this barrier on top of the gravel at the bottom of your terrarium. Slightly too big is better than too small to help ensure that soil is sufficiently trapped above, but for aesthetic effect, don't leave too much excess. When done correctly, this layer of plastic will be hardly noticeable in the final product.

4. Add a filtration layer of horticultural charcoal. While this step isn't strictly necessary, an additional charcoal barrier helps to filter impurities, which can stop any unpleasant odors that might arise over time. It also provides extra drainage space, which — as discussed earlier — can never hurt, especially if you accidentally go a little heavy-handed with watering. A long-handled paintbrush can help you evenly distribute the charcoal in this step, and you'll want to keep it handy for the next step, too.


5. Add your planting medium. Although some people like to create their own soil mixes, a general, all-purpose potting soil formulated for indoor use is really all you need for most terrarium setups. We personally use Edna's Best Potting Soil from E.B. Stone. Depending on the size of your terrarium and the plants you are growing, you might not need very much soil; a good rule of thumb is to have roughly the same depth  of soil as drainage layer, or perhaps a bit more.

6. Arrange hardscape elements to create the illusion of depth. This is the number one trick to creating a professional-looking terrarium. An easy place to start is by sloping the soil upwards towards the "back" of your terrarium, which will be determined based upon the orientation in which you plan to display the finished product. From there, you can heighten the effect by using stones or pieces of cork to create more dramatic changes in elevation for your miniature landscape — like tiny cliffs or rock faces. These also serve to hold back soil, which create natural places for planting.

Another way to create depth and drama is by creating a "vanishing point" with forced perspective. In our terrarium, we accomplished this by creating a small valley in the center of our design that narrows towards the back, in which we stacked three flat rocks of decreasing size, creating the illusion of a staircase connecting the low-lying area in the front of our terrarium to the "hill" behind.

7. Add your plants! As with your hardscape elements, think about creating depth and layers with your plants, placing taller ones in the back and shorter ones in front — perhaps leaving an open area in the middle. Feel free to get creative! And don't worry about leaving any "bare" patches; these can be covered with moss later on.

This is where a set of terrarium tools or aquarium tweezers come in handy — especially if your hands don't fit through the opening of your terrarium. These tools allow you to reach into your container to position plants and hold them in place as you anchor them in the planting medium. If you are trying to fit a plant into a tight space, feel free to knock off some of the soil from its roots to make it easier to plant. (We did this with our Pilea to make sure its main growth point was close enough to our cork "cliff" for the leaves to spill over easily.) If necessary, you can also perform some light trimming at this time to help realize your vision, but remember: If your plant requires a lot of chopping to help it fit in the space you can provide, you might want to rethink your selection.

8. Add moss to cover bare patches of potting soil. Using dried or preserved moss is a great way to obtain the look of live moss without having to keep it alive or risk introducing pests you might not have accounted for. Whether living or preserved, moss adds a carpet of green that really underscores the sense of scale in your terrarium, forming a groundcover layer of sorts. We can imagine a few clever designers using moss to give the impression of a lawn under a canopy of diminuitive houseplant "trees!"

9. Place your final decorative elements. This is the time to let your personality shine! If you're going for a naturalistic look, a few well-placed twigs might resemble miniature trees or fallen logs. For a fantastical flare, consider adding colorful stones or crystals. As with moss, fairy garden elements like these miniature mushroom accents we used really help the illusion of scale.

10. Water in your plants. We recommend spot watering your plants using a spray bottle with a "stream" setting. Targeting the base of individual plants with water rather than spraying down the whole container will help to ensure that you don't saturate your growing medium before your plants have had the chance to grow roots that can access this water. On a related note, if you plan to enclose your terrarium, it is a good idea to leave lid off for the first few weeks after planting to allow everything to get established. When water can evaporate out of your container, this minimizes the potential of damage from any overwatering mishaps that might occur — especially early on.

...And Voilà! Just like that, you have a finished terrarium. Step back and admire your creation.

Caring for Your Terrarium

Once you are happy with your masterpiece, find a good home for it based on the light requirements of the plants you have selected. Most terrariums will appreciate being placed in a spot that receives bright indirect light from a window, but be wary of a windowsill that receives hot afternoon sun, as this can cause too much heat to accumulate in a closed setup.

Watch your plants carefilly to see how they're acclimating to their new home and your watering schedule. Spot watering twice a week is probably a good place to start, depending on your plants. If you notice a lot of water accumulating in your drainage layer, you can cut back on your watering routine.

After some time, you will likely need to trim your plants back a little to keep your terrarium looking fresh and maintaining the illusion of miniature scale. This can be done with regular craft scissors if the opening of your terrarium allows; otherwise, most terrarium tool kits include long-handled trimmers perfect for getting the job done. In closed setups, you will likely also want to clean the glass occasionally to remove any algae that may form. After all, you've spent all this time putting together an awesome miniature world, and you ought to be able to see it! With a little care and planning, you can enjoy your terrarium setup for years to come.

We have a wide array of houseplants at the Farm just waiting to be explored, including miniature potted plants perfect for crafting your own terrarium or dish garden. And if you'd rather purchase a ready-to-go terrarium made with love by one of our team members, we have those, too! As always, feel free to ask us for help in picking out or caring for your plants — whether they're destined for terrarium life or not.