How to Create a Terrarium with Sphagnum Moss

Planting a terrarium is ideal for gardening indoors where space is limited for potted houseplants.  Terrarium gardens also are great for those who would like to try their hand at first time gardening.

A terrarium is the perfect answer for indoor container gardening in a tiny space.  Terrarium garden containers can be totally or partially enclosed, allowing heat and light to help the plants while holding moisture.  A terrarium can be totally sealed so there is no moisture loss; however, it is best to have the container remain partially open to permit air circulation.

Finished Terrarium

Project Difficulty

2/5

What You Will Need

  • A glass container with or without a lid
  • Mosser Lee’s Long Fibered Sphagnum Moss
  • Mosser Lee’s Horticultural Charcoal
  • Sterile potting mix
  • Latex gloves (Always wear gloves when handling moss, soil and plants.)
  • Large spoon
  • Plants

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We are using Mosser Lee’s Long Fibered Sphagnum Moss and Mosser Lee’s Horticultural Charcoal to help with water retention and to protect the plant roots from harmful pathogens which can develop more easily in a tight environment like a terrarium.

Directions to create your terrarium:

Add Dry Sphagnum Moss
  1. Place a two-inch layer of dry Mosser Lee’s Long-Fibered Sphagnum Moss in the bottom of the terrarium container. Long fibered sphagnum moss is excellent at retaining moisture for your plants and preventing root rot.
Wet Moss
  1. Wet the moss with water, but just enough for the moss to hold all the water. Compact the moss in the container so that the next layer will not drop through it. This wet layer should help your plants stay nourished. Hint: Wet the moss with a mixture of water and a mild water-soluble fertilizer suitable for your plants.
Add Charcoal
  1. Using a large metal or wooden spoon, add a ½ inch layer of Mosser Lee’s Horticultural Charcoal to the top of the wet moss. Horticultural charcoal is essential for keeping the water contained and inhibits the growth of bacteria which can damaging roots. It is especially necessary in planters with no container bottom drainage holes.

  1. Add about two inches of the potting mix on top of the Mosser Lee’s Horticultural Charcoal making sure you are leaving room for your plants to fit in the terrarium container.
Add Potting Soil
  1. Make holes in the potting mix to accept your plants and place them in the design, keeping in mind that the plants need unobstructed growth.  Hint: Use long tweezers or sugar tongs for smaller plants or when your container is small. Pat the soil down around the plant very gently.  
Finished Terrarium
  1. Place other items in your terrarium to add interest, such as bark, gems and sea glass or fairy items. Consider adding sheet moss or reindeer moss to add color and reduce soil moisture evaporation. (Picture includes two different colors of reindeer moss, bark and a red sprinkling can.)

  1. Water your plants by lightly spraying them with a spray bottle to dampen plants, carefully not to soak them. Remember, the plant roots will find the wet sphagnum moss for nourishment.

Choosing a Container:

Terrarium containers can be any glass container.  Mason jars, goldfish bowls or a wide-mouthed jar are ideal. The wider the opening, the easier it will be to build the terrarium, facilitate planting and placing any decorative pieces.

Choosing your Plants:

For an attractive display, think about design and placement of your plants.  Consider tall and short plants and a variety of texture, form and foliage of plants.  Try to choose plants suited to a humid environment in a terrarium and ones that prefer low to medium light.  Plants with large leaves will shield light from smaller plants.  Small ferns such as the button fern are delicate and elegant looking.  Another low growing, lovely plant suited for a small terrarium garden is baby tears. Also, the starfish plant maintains a low growth habit with leaves that change colors depending on the intensity of the light. The prayer plant, peperomia and croton are well-suited for a large container.  Sometimes small, spike-like flowers will appear on the peperomia, lending interest to your terrarium garden. Succulents are popular terrarium plants.  Those belonging to the Haworthia family have a variety of plants well-suited to a terrarium garden.  They are slow growers, and many of them grow 3 to 5 inches tall.

Additional Tips to Maintain Your Terrarium:

  • Aggressive fertilizing terrarium plants once planted is not necessary since fertilizing will result in your plants growing larger than the terrarium space.
  • Terrariums whether totally or partially enclosed retain water. The wet sphagnum moss should keep the roots adequately nourished, however check the soil once a week to see if it is dry.  Terrariums require less water than potted houseplants.
  • Closed terrariums will breed condensation.  To remove condensation, remove the top of the container to release air about once every month.