You need to make the most important choice of the whole process before you start building or even planning your terrarium.
Your choice will have far-reaching implications (at least as far as your terrarium is concerned). It dictates the type and number of plants and animals you can include. It will impact the aesthetics and the longevity of the system. It’s the difference between regular maintenance and no maintenance at all!.
We touched on it in the last chapter (Can a terrarium be self sustaining?), but it bears repeating. A sealed terrarium has no exchange of matter with the outside. It has two important corollaries:
Of course, like everything in life, it’s not quite black and white. Since terrariums can be made in lots of containers, there are varying degrees of “sealedness”. A pickle jar with the lid screwed on tight is about as sealed as you can get. It’s hard to completely seal those big terrariums made from fish tanks, and you probably wouldn’t want to.
Theoretically, if you were creative enough (and had silicone), you could seal anything. However, some containers are better off not being sealed at all or completely.
It’s also worth mentioning that there’s a bit of an in-between method. It’s common to make a sealed terrarium that is only opened sometimes to water, clean, and generally freshen things up.
And, actually, that method is a great compromise. It makes making a sealed terrarium a lot easier and less complicated, but it usually needs a lot less care than an open terrarium anyway.
This third category doesn’t really qualify as either sealed or unsealed. If it’s ever opened, even once, you break the seal (literally) and it’s no longer truly self-sustaining. As far as science is concerned, at least. You wouldn’t be able to use that terrarium as data because it was compromised.
Of course, that’s a moderately pretentious viewpoint. Not many of the people reading this plan to use their jar of bugs and plants as a research point. Ultimately, you should use whichever strategy brings you the most satisfaction.
That last one might not even be a con. Maybe I’m the only one who thinks that way.
As the creator, it’s up to you, but for the purposes of this site, most of the lessons and guides will be about how to make a sealed terrarium. After all, you’re on SelfSustainingEcosystem. com!.
That perspective can be considered a “restricted” view on terrariums. With a few small changes, everything we talk about will also work for unsealed (or sometimes unsealed) terrariums, so it’s all useful information.
There are no terrarium police enforcing the rules and regulations on sealed vs unsealed. Do what you want, try new stuff, learn along the way. Tell us what you discover!.
Terrariums are miniature indoor gardens enclosed in glass containers. Their charming, whimsical nature has made them increasingly popular for bringing a touch of nature inside. But do these tiny ecosystems really need a lid? The answer depends on the type of terrarium and plants inside. Let’s explore the purpose of terrarium lids and when they may or may not be necessary.
What is the Purpose of a Terrarium Lid?
The primary purpose of a lid is to keep humidity and moisture levels high inside a closed terrarium. The lid essentially creates a greenhouse effect trapping water vapor given off by the soil and plants. This warm humid microclimate suits tropical plants that thrive in rainforests and other steamy environments. By recycling moisture, a lid allows these plants to grow happily in the enclosed space without needing frequent watering.
Closed Terrariums Require Lids
Closed terrariums, featuring lids and completely sealed off from the outside environment, are ideal for tropical plants. Without a lid, humidity would quickly escape. The sealed lid keeps moisture in and allows tropicals like ferns, mosses, orchids, begonias and venus fly traps to flourish. These plants need consistent humidity between 60-100%.
Open Terrariums Don’t Use Lids
Plants that prefer drier conditions do best in open terrariums without lids. Succulents and cacti, for example, can rot and die from too much moisture. An open terrarium provides the air circulation and evaporation these desert plants need to mimic their natural habitat. Excess humidity is purged rather than trapped.
Problems That Can Occur Without a Lid
Neglecting to use a lid for a closed terrarium can cause issues:
- Low humidity from moisture escaping quickly
- Plants drying out faster, requiring more frequent watering
- Inability to maintain the warm, tropical environment expected by plants
- Greater temperature fluctuations from exposure to room air
Proper plant selection and more attentive care can help, but results may not be ideal.
Tips for a Lidless Closed Terrarium
While closed terrariums benefit greatly from lids, you can craft a lidless one with care:
- Choose plants suited for low humidity like ferns, pilesas, peperomias. Avoid tropicals.
- Use a tall, narrow container to retain some humidity.
- Mist frequently to manually increase humidity.
- Monitor soil moisture closely and water when just slightly dry.
- Keep terrarium in a warm, stable environment away from vents and windows.
Alternatives to Traditional Glass Lids
For those desiring a more open terrarium but seeking some humidity retention alternatives to fully sealed lids exist
- A lightweight screen lid maintains airflow while trapping some moisture.
- A removable pane of glass or plastic can act as a temporary lid added only when needed.
- Horizontal driftwood or a decorative stick laid across the top opening creates a small humidity gap.
- A band of moss snugly encircling the terrarium opening covers just enough area to boost humidity.
The Necessity of Lids Comes Down to Balance
Ultimately, whether a lid is needed comes down to balancing the humidity-loving needs of the plants with the desired aesthetics and functionality of the terrarium. Tropical closed terrariums require lids to thrive. For drier open terrariums, lids pose problems. With creativity and proper plant choices, lidless terrariums can work, but require vigilance in maintaining conditions. Consider both the plants’ needs and your own when deciding on a lid!
Open Terrariums are Plant Pets
You’re probably starting to see the difference.
An unsealed terrarium is basically a potted plant, or rather, a community of potted plants. You generally keep them around for aesthetics; they can be absolutely gorgeous. There are lots of ways to make it your own. A lot of people add crystals, statuettes, or gnomes.
Unsealed terrariums come with many of the same benefits and drawbacks of potted plants, too. You have to devote time to taking care of them every 1-3 days. Tropical plants, like those usually used in terrariums, are generally a bit more needy in this way.
Perhaps the biggest drawback is that you can’t really put any animals in an unsealed terrarium. Or, you could, but then it would probably be classified as a vivarium or something instead. What’s the difference between a bio-active lizard vivarium and an unsealed terrarium? Just the lizard, really.
Self-sustaining terrariums need a lot of bugs and microorganisms, which are exactly the things you don’t want coming into your house. You might be able to keep some springtails in an open terrarium, but not much else. It could be healthy, sure, but not really an ecosystem in a jar.
Do Terrariums Need Air? The SIMPLE Answer!
FAQ
Can you have a terrarium without a lid?
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