Containers for terrariums should optimally be made from glass because it is clear and tends to maintain a consistent temperature. When picking suitable glass for a terrarium, there are three major things to consider: transparency, airflow, and headroom, so the plants can breathe.
Transparency
The glass you choose for a terrarium must be clear. It may be slightly tinted, such as recycled glass (which usually has a blue or green cast), but fully colored glass will not allow the right light spectrum to penetrate the container, which plants need in order to be happy. This is especially true of green glass, in which plants will not grow (according to Michelle’s chemistry professor at Brooklyn College).
Airflow
The amount of airflow needed will depend on how moist the plant likes to be, and airflow is determined by the size of the terrarium’s opening. For most moss terrariums, the container must have a lid or a small opening so that moisture stays inside; that way, the terrarium can monitor its own moisture, and you will only have to check on it every few weeks. In contrast, shade-loving plants (like peacock spikemoss and asparagus ferns) need containers with larger openings since they don’t like to be as moist as moss.
Headroom
Sure, great terrarium glass can be as small as a salt shaker or a vintage Chanel bottle. But whatever you fancy, you’ll need to reserve some headspace at the top—usually about half of the container—to retain enough air to keep moss or plants healthy. Containers for succulents should have no walls at all, or very low ones at most so the glass doesn’t fry the succulents or retain so much moisture that they rot.
A Note on Plastic
Plastic terrariums aren’t totally out of the question—there are some super fun and funky containers from the 1970s that I love. But I’ve found that plastic reacts differently in changing temperatures and usually produces a lot more condensation than glass, which makes them trickier to maintain.
Glass is the optimal material for terrarium containers, and there are lots of types available. I like to use repurposed glass when possible, but almost any transparent glass will do the job.
- ANTIQUE AND VINTAGE GLASS
- RECYCLED GLASS
- NEW GLASS
- CRYSTAL
- HAND BLOWN GLASS
1. Antique and Vintage Glass
I love to use existing materials in order to reduce the use of new raw materials, and terrariums can be a perfect way to upcycle glass. According to antique experts (the upcycling gurus), glass must be more than one hundred years old to be considered “antique.” Glasses more than twenty but less than one hundred years old are “vintage.” Antique and vintage containers tend to have minor defects, such as air bubbles from old manufacturing processes, or nicks from having been around the block, but this can lend to their charm. A vintage pickle jar, an antique apothecary jar, an old compote bowl with lid (or without, if you’re using succulents), or even an old Mason jar…all of these are great terrarium finds.
2. Recycled Glass
Most recycled glass comes from two places: Spain and Italy. Spanish recycled glass has a very pretty aqua tint to it, while Italian recycled glass tends to have a greenish cast. Don’t worry, the tint is subtle enough to let light filter through. Both types are beautiful and look great as a terrarium! Some vessels have cork lids, which can add to their charm (and practicality). There are varying degrees of quality in recycled glass, and it’s usually best to look at the item in person before purchasing. Some of this glass is thick and hard to see through—thin, transparent recycled glass is preferable. It can be very hard to tell the difference online, and photos can sometimes misrepresent the real thing.
3. New Glass
If you find a new piece of glass in your favorite store that would be perfect for your terrarium, then you may not want to look further. That’s okay! With all the new glass products out there, it’s easy to find something you like without breaking the piggy bank or searching high and low in antique shops.
4. Crystal
If you don’t mind the high price tag, crystal is an elegant way to house a terrarium. Crystal vessels are usually perfectly clear. Lead is added to glass in order to create many types of crystal containers, and this is what gives it significantly more shine and makes it so clear. However, this also makes the glass softer, and I’ve been told that the higher the lead content, the more likely it is to shatter. For this reason, I recommend that crystal terrariums be kept away from children, but you probably knew that already.
5. Hand Blown Glass
Hand blown glass terrarium containers are available in more unique shapes than traditionally manufactured glass containers. It is also possible to ask a glassblower to customize a terrarium just for you. It’s an expensive option, but the results can be amazing.
In conclusion, glass is the optimal material for terrarium containers, and there are lots of types available. I like to use repurposed glass when possible, but almost any transparent glass will do the job.