How to Make a Cactus Terrarium – Ultimate Guide

Cacti are generally hardy plants but are not ideal for a closed terrarium. However, you can get the desert theme on your tabletop by creating an open cactus terrarium. It’s no longer rocket science as long as you can provide proper airflow, well-draining soil, bright indirect light, and minimal watering.

When choosing cacti for a terrarium, opt for small and slow-growing varieties that won’t outgrow the terrarium quickly. Consider plants with different shapes, colors, and textures to create an appealing arrangement. I used the moon cactus, golden barrel cactus, and the rosy pincushion cactus.

Typically use the plants you already have in your cactus collection or purchase new ones from a store or nearby gardening center. You can grow more than one species of succulents in your terrarium as long as it’s spacious enough and the plants are compatible with their growth requirements.

How to make a cactus terrarium

Terrarium setup is a pretty simple task as long as you have all the materials needed. Once you have decided on which cactus to use, you’ll get the following:

A wide open clear container

Get a glass jar, a bowl, or a vase that is large enough to hold your plants. Your preferred container should be wide open at the top to allow free flow of air. 

Pear gravel or small rocks

You’ll need about one pound of pea gravel or small rocks which will be layered at the bottom of the container to collect excess water that drains from the potting media. Cacti are prone to root rot when overwatered or grown in waterlogged soil.

A piece of fine mesh

Get a piece of fine mesh that will help in preventing the cactus soil from compacting into the pear gravel. I prefer using windscreen mesh since it is easy to cut into sizes that fit in the container.

Succulent or cactus mix

You’ll need a well-draining soil mix specifically formulated for cacti and succulents Do not use regular potting soil as it can encourage root rot. You can also make your own cactus soil by combining regular potting soil with coarse sand and pumice.

Terrarium decorations

To create an appealing desert tranquility, you’ll need to add some decorations to the terrarium. Get some colored sand, sea shells, or small animal toys like lizards.

Steps for creating a cactus terrarium

1. Start by washing your container with a mild soap and clean water to remove any contaminations and dry it out completely with a dry piece of cloth or towel.
2. Fill the bottom of the jar or vase with pea gravel to half-full and spread them out to form an even layer.
3. Cover the rocks with a piece of fine mesh and ensure it completely fits. You may use sharp scissors to cut the mesh into shapes.
4. Pour about 3 inches of cacti soil to cover the wire mesh and spread it out evenly. Avoid using any standard substrate as it can cause retention of excess moisture around the roots.
5. Transplant your cactus into the soil and gently press around its roots to secure them in the soil. Be cautious of the cactus spines and use thick gloves when handling them.
6. Spread a thin layer of colored sand on top of the soil and add a few decorative rocks. twigs and animal toys can also make the terrarium look natural.

You can grow cacti and other species of succulents in the same container but make sure the terrarium is not overcrowded. Just make sure that both plants have similar requirements for light, watering, and temperature. 

Caring for your cacti in the terrarium 

Caring for cacti in a terrarium isn’t complicated but it requires a slightly different approach compared to their care in regular pots. Here is what you need to provide:

Lighting

Cacti need plenty of bright, indirect light to thrive. Be sure to place your terrarium in a location where the plant can receive at least 4 to 6 hours of sunlight per day. If your home doesn’t have enough natural light, you can supplement it with artificial grow lights.

Without sufficient light, cacti may become etiolated (stretching towards the light source) and lose their typical compact and sturdy form.

Watering

Water terrarium cacti sparingly, allowing the soil to dry out completely between the waterings. In a terrarium, the moisture can easily accumulate and that can result in cactus rot and other fungal problems. So, monitor the soil moisture level and adjust your watering accordingly. 

Temperature and humidity

Most cactus plants thrive in warm temperatures and low humidity. Therefore, keep the terrarium in a relatively dry area with a temperature range of  65-80°F (18-27°C). If the humidity inside the terrarium becomes too high, consider providing additional airflow.

Fertilization

While cacti have low nutrient requirements, feed sparingly during the active growing season (spring and summer). Use a diluted, balanced fertilizer specifically formulated for cacti and succulents. For best results, follow the instructions and application rates on the fertilizer packaging.

Potential problems

While some terrariums have transparent walls, they often reduce the amount of light that reaches the plants inside and this can affect their health. There is also a likelihood of poor air circulation, which can result in the growth of mold in the terrarium. 

Cacti are prone to root rot when overwatered. Moisture issues can also encourage insect pests such as mealybugs, scale, and aphids. Therefore, it’s important to regularly inspect your cacti for signs of distress and promptly address the underlying problem.

Final thought

You can create a desert-like display in your home by creating a cactus terrarium. Since cacti have adapted to survive in dry conditions with excellent drainage you must provide good airflow, well-drained soil, and plenty of indirect sunlight for them to thrive.

References

Cacti care – University of Nebraska Extension

Holiday cactus – University of Wisconsin-Madison

INDOOR CACTI – Clemson Cooperative Extension