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Create a microclimate

Create a microclimate
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Build a small sealed terrarium to create a microclimate, observe temperature, humidity, and plant growth over several days to learn ecosystem basics.

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Step-by-step guide to build a sealed terrarium

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What is a microclimate?

What you need
Activated charcoal (optional), adult supervision required, clear jar or plastic container with tight lid, paper and pencil, potting soil, small moisture-loving plants or moss, small pebbles or stones, small spoon or trowel, small thermometer and hygrometer, spray bottle with water

Step 1

Gather all the Materials Needed and place them on a clean table so everything is easy to reach.

Step 2

Wash the jar and lid with soap and water and dry them so your terrarium starts clean.

Step 3

Put a 1 to 2 inch layer of small pebbles or stones into the bottom of the jar for drainage.

Step 4

Sprinkle a thin layer of activated charcoal over the pebbles to help keep the air fresh.

Step 5

Spoon in potting soil to make a planting layer about 2 to 3 inches deep depending on your jar.

Step 6

Place your small plants or moss into the soil and gently press soil around their roots to hold them in place.

Step 7

Lightly mist the soil and plants with the spray bottle until the soil feels damp but not soggy.

Step 8

Place the small thermometer and hygrometer inside the jar against the glass where you can read them from outside.

Step 9

Read the thermometer and hygrometer now to get the starting temperature and humidity.

Step 10

Write the starting temperature humidity and the date and time on your paper so you have a record.

Step 11

Close the jar tightly with the lid to seal the microclimate inside.

Step 12

Put the sealed terrarium in a spot with gentle indirect light away from direct sun and heaters.

Step 13

Each day at the same time for several days read the thermometer and hygrometer to watch changes.

Step 14

Each day at the same time for several days write the temperature humidity and one short note about how the plants look on your paper.

Step 15

Share a photo and what you learned about your microclimate and plant growth on DIY.org.

Final steps

You're almost there! Complete all the steps, bring your creation to life, post it, and conquer the challenge!

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Help!?

What can I use if I can't find activated charcoal or a small hygrometer?

If activated charcoal is unavailable for the step that says to sprinkle a thin layer over the pebbles, substitute a thin layer of coarse sand or aquarium gravel or buy horticultural charcoal from a garden center, and if you don't have a hygrometer place a small digital thermometer inside as instructed and use visible condensation on the glass as a simple humidity indicator.

What should I do if the soil becomes soggy or mold starts to grow?

If soil is soggy or you see mold, open the jar to air it for a day, remove any rotting leaves, reduce how much you mist with the spray bottle, and double-check that the 1–2 inch pebble layer and charcoal drainage layer are correct per the instructions.

How can I adapt this microclimate activity for different age groups?

For younger children have them do simpler tasks like washing the jar, adding pebbles, and placing plants with adult help sealing the jar, while older kids can measure 2–3 inches of potting soil, position the thermometer and hygrometer, record daily temperature/humidity readings and notes, and design small experiments.

How can we extend, improve, or personalize our terrarium project?

Extend and improve the activity by creating two sealed jars placed in different indirect light spots to compare daily thermometer and hygrometer logs, personalize by decorating the jar and adding tiny figurines, and enhance documentation by photographing plant changes for your DIY.org post.

Watch videos on how to build a sealed terrarium

Here at SafeTube, we're on a mission to create a safer and more delightful internet. 😊

What Is Micro Climate? - Weather Watchdog

4 Videos

Facts about terrariums and microclimates

💧 A sealed terrarium makes its own tiny water cycle—water evaporates, condenses on the glass, and drips back like rain.

🔬 A teaspoon of potting soil can hold millions of microbes that break down waste and recycle nutrients for your plants.

🌿 A well-balanced closed terrarium can stay moist and support plant life for months or even years without added water.

🌱 Mosses, ferns, and baby plants are great terrarium choices because they love the humid, low-light conditions.

🌡️ Small temperature changes inside a jar can change how fast plants transpire and how active the microclimate is.

How do we build a small sealed terrarium to create a microclimate and observe temperature, humidity, and plant growth?

Start with a clear jar or plastic container with a tight lid. Layer small stones for drainage, add activated charcoal to keep water fresh, then a thin layer of potting soil. Plant small, slow-growing plants (moss, baby tears, fittonia) and lightly water. Close the lid and place the terrarium in indirect light. Use a thermometer and hygrometer to record temperature and humidity daily, and note plant changes over several days.

What materials do I need to build a sealed terrarium microclimate?

You’ll need a clear glass or plastic jar with a sealable lid, small stones or pebbles, activated charcoal, potting soil, small plants (moss or tiny houseplants), a spray bottle, and a small spoon or trowel. Optional: a small thermometer and hygrometer for measurements, labels, tweezers for planting, and gloves. Avoid plants that grow quickly or need direct sun for this sealed setup.

What ages is this sealed terrarium activity suitable for?

This activity suits children about 5 years and up with adult help; younger kids can participate in simple steps like placing stones. Ages 8+ can follow steps more independently and take measurements. Always supervise handling glass, soil, and small parts. Adjust responsibilities by age: toddlers can observe and water under supervision, while older children can record data and make changes to the microclimate.

What are the benefits and safety tips for children when building a sealed terrarium?

Terrariums teach ecosystem basics, curiosity, observation skills, and responsibility for living things. They reinforce measurement and recording habits and fine motor skills. Safety tips: choose non-toxic plants, avoid glass with very young children, supervise when using soil or charcoal, and don’t overwater. Teach kids not to open the sealed jar frequently. Variation ideas include open terrariums, adding a small LED light, or using small sensors for temp and humidity.
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