Nature in Miniature: Terrariums

Susan Warrenfeltz
Frederick County Master Gardeners

Terrariums are the perfect "houseplant" for busy gardeners! They take up very little room and require little or no maintenance. They can brighten up the grey, winter landscape. But most importantly, a terrarium can be a self-sufficient environment which will thrive on neglect.

The materials needed to create a thriving ecosystem consist of a clear container, drainage medium (stones), horticultural charcoal, a separation barrier, and plants.

A clear container: Virtually any clean, clear glass or plastic container will work. Avoid colored or cloudy containers. Containers with lids make the most efficient terrariums by requiring limited watering. Wash and dry your container thoroughly.

Drainage: Pea gravel, river stones, or aquarium rocks are all acceptable choices for drainage mediums. Avoid marble chips or other calciferous rocks. Whatever your choice, ensure they are clean.

Horticultural Charcoal: Charcoal is important for filtration, drainage, and reduction of odors. Use only horticultural charcoal.

Separation Barrier: Window-type screening, sphagnum moss, or similar thin material will be layered between the soil and drainage medium. The barrier should approximate the diameter of the container.

Soilless Mix: Sterilized, soilless mix is recommended to reduce the possibility of creating an unhealthy environment. The quantity required should fill slightly less than 1/4 the height of the container. Moisten 3/4 of the soil, setting aside 1/4 to remain dry.

Plants: Terrariums may consist of one specimen or a grouping of varied types and textures. Select plants suited to the type of environment to be created. For example, a woodland terrarium requires medium light and medium humidity. For a multiple plant environment, select plants with the same light and moisture needs. Choose miniature versions of plants, or plan on renovating the terrarium as plants grow.

Decorative Accents: For decorative interest, add statues, seedpods, stones, moss, or branches.

Water: Water used in the terrarium should be distilled. Tap water may be used if it is allowed to sit uncovered overnight so the chlorine dissipates.

Planting requires only a few steps once you ensure that all of your materials are clean and disease free.

Prepare the Drainage Layer: Mix 3 parts pebbles to 1 part charcoal. This layer should be - 2 inches thick, depending on size of container. Top the drainage layer with the separation barrier.

Add the Soilless Mix: 3-5 inches of mix is a general guide. Together the mix and drainage should occupy approximately 1/4 to 1/3 of the height of the container. First add the dry mix, which should form a layer about 1/2 inch thick over the separation barrier. Top with half or more of the damp mix, reserving the remainder.

Add the Plants: Remove each plant from its pot, gently remove excess soil, and plant it in the container at the same depth as it was in its pot, adding soil as required. Add decorative accents, or top the soil mix with moss. Wipe dirt off plant leaves with a paintbrush and remove smudges on the sides of the container.

Water: Water the terrarium lightly by spraying the leaves. Allow the terrarium to sit uncovered for 24 hours. The water level in the drainage layer after this period should not exceed inch. When this level is reached, mist lightly again, allow the leaves to dry, then put on the lid.

Enjoy: Place the completed terrarium in indirect light in average room temperatures. Rotate the container periodically. Ventilate every 2 3 weeks for 1 hour. Water when condensation does not appear on the glass after ventilation. Avoid fertilizer, which causes excess salts to form.

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