How to Make a Lovely Closed Terrarium In a Jar

A successful terrarium lasts years

By
Kerry Michaels
Kerry Michaels

Kerry Michaels is a container gardening expert with over 20 years of experience maintaining container gardens in Maine. She specializes in writing and capturing photography for gardening and landscape design for print and broadcast media, including the Discovery Channel, Small Gardens, and Disney, among others.

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Updated on 04/02/23
Reviewed by
Julie Thompson-Adolf
Julie Thompson-Adolf
Reviewed by Julie Thompson-Adolf

Julie Thompson-Adolf is a Master Gardener and author with over 30 years of experience in year-round organic gardening; seed starting, growing heirlooms, and sustainable farming.

Learn more about The Spruce's Review Board
Mason jar terrarium with small plant and rock inside closeup

The Spruce / Adelyn Duchala

Project Overview
  • Working Time: 15 - 30 mins
  • Total Time: 30 mins
  • Yield: One terrarium
  • Skill Level: Beginner
  • Estimated Cost: $20 to $40

Mason jar terrariums make great gifts for teachers, as housewarming gifts, or as a way to bring sunshine into the world of a friend. Depending on the plants, these terrariums are inexpensive and can last for years. They thrive on neglect, so even a determined serial plant killer can keep one of these alive.

Making a terrarium in a mason jar is easy but requires a little finesse because you are working with a very small planting area. While you can make a standard terrarium by planting them right side up, the look of the upside-down jars is very appealing. To do this, you use the lid for your planter. 

Do Jar Terrariums Need Charcoal?

Activated charcoal is sometimes used in terrariums to help remove impurities from the air and water. It's often used as the drainage layer of the substrate materials. It can help to prevent mold and mildew growth and reduce humidity. It's not required for all terrariums, but it is helpful. However, over time, it is no longer effective.

Instead, use several alternatives to charcoal. One option is using moss as a layer that can absorb odors and excessive water, like activated charcoal. It can also help stabilize humidity levels if plants love high humidity. Another alternative is to use filtered or distilled water instead of tap water. Tap water can introduce chlorine, lead, or minerals that can leave deposits.

Another charcoal alternative is using springtails (small wingless insects) or isopods (miniature crustaceans) as your terrarium cleaners. Springtails feed on fungus, mold, and decaying matter in your terrarium. Similarly, isopods keep a terrarium clean by eating away unwanted materials, fertilizing the soil, and making it soft by tunneling.

25 Easy Terrarium Plants for Open or Closed Glass

What You'll Need

Equipment / Tools

  • Spray bottle or plant mister

Materials

  • Mason jar (or any other jar with a screw-on lid)
  • Small plants
  • Springtails or isopods (optional)
  • Moss (optional)
  • Activated charcoal (optional)
  • Stones, shells, ornamental objects (optional)
  • Raffia ribbon (optional)

Instructions

Materials and tools to create a mason jar terrarium

The Spruce / Adelyn Duchala

Instructions for Making a Simple Jar Terrarium

  1. Prepare Your Jar

    If you use glass cleaner or a harsh soap, make sure to wash out the jar after and let it air out completely. Next, take your jar top and put it on a flat surface, making sure the center disk is securely placed in the lid.

    Mason jar washed on outside of glass with white towel

    The Spruce / Adelyn Duchala

  2. Moisten the Soil 

    Dampen the potting medium of your plant and then remove its pot or cell, making sure not to pull it out by the top. If it is in a pot, tap the pot and slide the plant out by gently squeezing the sides and tipping it into your hand. If your plant is in a cell pack, squeeze the bottom and push the plant out. If the plant is rootbound, rough up the roots either by rubbing them or tearing them at the bottom

    Small plant slid out of pot and soil dampened with mist container

    The Spruce / Adelyn Duchala

  3. Place the Plant

    Squeeze the root ball and then place the plant in the lid of the jar. You want the root ball to be compact and if possible, have all the roots covered with soil. Press the root ball into the lid so that it is mounded, but doesn't overflow.

    Plant rootball pressed into mason jar lid and covered with soil

    The Spruce / Adelyn Duchala

  4. Add Moss (Optional)

    To give the terrarium a finished look, take small pieces of moss and press them onto the soil around the plant, creating a nice green mound. Keep the moss away from the crown of the plant.

    Small moss pieces pressed around plant base to create mound

    The Spruce / Adelyn Duchala

  5. Test Fit the Jar

    Carefully corral the leaves and branches of your plant so they will fit into the jar, being careful to push the leaves and branches up. Gently place the bottle over the plant, using your fingers to push the greenery into the jar. Twisting the jar can help. If possible, keep rotating the jar until the threads of the lid catch.

    Tip

    This assembly is a bit tricky and even if you can't make the threads catch, you can rest the lip of the jar on the lid and create a seal. Just be careful to remember this when moving the jar and pick it up by the lid and the glass.

    Mason jar placed over plant to test the fit

    The Spruce / Adelyn Duchala

  6. Dress Up Your Terrarium

    You can use any great terrarium plants that will fit. To add a whimsical or decorative touch to your terrarium, place stones, shells, miniature figurines, or anything else that will survive the humid atmosphere of a terrarium. Make "memory" terrariums by collecting and adding keepsakes from vacation, and create a terrarium with those as the theme.

    To give as a gift, simply tie a ribbon or piece of raffia around the lid of the mason jar.

    Small stones placed around base of plant for decoration

    The Spruce / Adelyn Duchala

  7. Care for Your Terrarium

    Keep it out of direct sunlight, but try to give it bright indirect light. You may not have to water it for months, though you should check every few weeks to make sure the soil is moist, not wet. If you see lots of condensation on the jar, leave it open for a few hours to dry the soil out a bit.

    Terrarium plant being misted with water to keep soil moist

    The Spruce / Adelyn Duchala

Terrarium Care and Tips: 10 Mistakes to Avoid