Plant Terrariums: 13 Things To Know

Plant terrariums are known for being refreshingly low-maintenance indoor planters for homes and office spaces alike. When constructed and cared for appropriately, terrariums can last for many years and bring a touch of nature inside to cure those biophilia blues. So whether you live in a dry or humid climate, there’s a terrarium model that’s just right for your space.

How Do You Choose Plants For Your Terrarium?

Choosing the flora for your plant terrariums is one of the most interesting and fun parts of owning a plant terrarium. As a general rule, it is wise to stick with plant varieties that are either dwarf species or at least slow-growing species.

For open-style terrariums, it is best to stick with plants that prefer a dry, arid environment. Consider air plants, cacti, and succulents.

For closed-style terrariums, you should choose more tropical plants that appreciate moisture.

What Do You Need To Build A Plant Terrarium?

Plant terrariums are relatively simple in construction and require a short list of supplies. To begin, you will need a glass container, a large substrate such as gravel or rock, sterile soil, activated charcoal, and the plants of your choice.

While they aren’t required, you will have greater success with your plant terrarium if you also pick up some long tweezers, long plant trimming scissors, and a mister bottle.

Should A Plant Terrarium Be Open Or Closed?

Both open and closed-style terrariums are functional and beautiful; however, they should be planted and cared for very differently. 

Closed terrariums are great for sub-tropical plants that enjoy constant moisture. However, open terrariums are much better for plants that need plenty of airflow and are susceptible to mold or rot.

Why Do You Need An Activated Charcoal Layer In A Plant Terrarium?

Closed-style plant terrariums require a layer of activated charcoal to purify any toxin build-up in the soil or water. Without the charcoal, the water would go stagnant and begin to grow bad bacteria which will kill plants and smell rather badly.

If your terrarium is open, you don’t absolutely have to have charcoal, but it is still beneficial.

How Do You Plant A Terrarium?

First, gather the supplies that we discussed needing earlier in the article. Then, once you have everything together, sterilize all of your tools to avoid introducing harmful bacteria to the environment.

Place 1-2 inches of your large substrate at the bottom of the terrarium. On top of this layer, you will place roughly ⅛ inch of activated charcoal.

The third layer of your terrarium should be sterile potting soil. Then you can start adding your plants and any other decorative items you want to include.

When Should You Water Your Plant Terrarium?

Open and closed terrariums have very different watering requirements. 

You will only want to water roughly every 3-5 weeks for open terrariums with arid plants. You should regularly check the soil humidity, however, to ensure that it is still somewhat moist.

Closed-style terrariums benefit from regular misting but should be monitored for problems such as mold and algae.

Do Plant Terrariums Require Sunlight?

Terrarium plants do require sunlight, just like other houseplants. Direct sunlight, however, is not advised for open or closed terrariums. 

Terrariums prefer low to medium indirect sunlight and flourish under these conditions when near a North-facing window.

Are Plant Terrariums Hard To Maintain?

While plant terrariums are typically very easy and simple to care for, there is certainly a learning curve to building and caring for them. If you’re an avid gardener, you may need a reminder not to fuss with terrariums as much as you do with other plants.

On the other hand, if you have no experience caring for plants, these low-maintenance planters may be easy to forget about entirely. Mark it down on your phone or calendar to help remind you to check on your terrarium conditions regularly until you know your terrariums maintenance schedule.

How Long Will A Plant Terrarium Last?

Plant terrariums can potentially last for many years if they are appropriately constructed and taken care of properly. Unfortunately, the most common reason for terrarium plants failing to thrive long-term is that their owners forget them or lose interest over time. 

While they are relatively low-maintenance house planters, they do still require some basic care to live.

Are Plant Terrariums Self-Sustaining?

Open terrariums are self-sustaining without any interference or care for up to 1-2 months but do require some occasional water and clean up every 1-2 months.

Closed terrariums can self-sustain for up to 6 months without any interference or care. However, they need to be aired out at least 2-3 times per year to release their greenhouse gas build-up and let in some fresh oxygen. 

What Are The Most Common Problems With Plant Terrariums?

The most common problems with plant terrariums are the same as those that plague other house plants. Terrariums need the proper balance of sunlight, water, and air for their plant residents to thrive. 

When they are kept in less than ideal environmental circumstances, terrariums will develop problems with water rot, mold, algae, harmful bacterial growth, and stagnant water. Activated charcoal should suppress the majority of these problems in your plant terrarium, however.

Why Do Plant Terrariums Fog Up?

Plant terrariums do not actually produce fog; they produce condensation. Condensation should occur roughly once per day in an enclosed terrarium space and then be reabsorbed by the micro-environment. 

If your closed terrarium does not produce condensation, try adding a teaspoon of water to it daily until condensation does occur. If your terrarium has too much condensation, try placing a silicate pack in the wettest area for a few hours and then remove it. 

Why Causes Mold In Plant Terrariums?

If your terrarium contains too much moisture and not enough oxygen, it will most likely cause fungal and mold growth on the surfaces of your plants and soil. This occurs when there is so much water that the soil and plants can not absorb it all to undergo their daily life processes.