Garden Variety: Build a terrarium garden at home

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Terrarium gardens are a fun and educational activity for people of all ages, and they can be as simple or as complicated as you want. Terrarium gardens are appropriate year-round (and should last for years), but winter building offers a special opportunity to connect with nature when the weather keeps many people inside.

A terrarium is a miniature ecosystem in a clear container. When set up properly, they require little maintenance. For young people especially, they teach about the water cycle and plant growth through visual display.

To make a terrarium garden, you need a clear glass or plastic container that can be sealed or closed; potting media (soil); pea gravel or other small rocks; and small tropical plants that fit in the chosen container. Activated charcoal may also be used, but it is not essential.

For a simple terrarium, you can use a plastic 2-liter bottle or a glass jar. If you want a larger terrarium, consider a vase, a cookie jar, a fishbowl or any other clear glass container with a lid, or use specialized vessels designed for use as terraria. Containers may be turned on their side to increase planting space.

Quality potting media are crucial to success. Use a potting mix that is labeled for the types of plants you’re using, whether that’s tropical plants or cacti and succulents. These mixes are engineered to provide the support, drainage and air space necessary for plant growth in an indoor environment. Low-quality potting mixes and garden soil are too heavy and provide inadequate drainage in this sort of environment.

To get started, wash or rinse out the inside of the container and allow it to dry. If using a plastic 2-liter bottle, cut it into two pieces about two-thirds of the way up the bottle for easy access. Keep both pieces and tape them back together after planting.

Add pea gravel, perlite or other small rocks to the bottom of the container. For very small containers, a thin layer of rocks is all that is needed. For a 2-liter bottle, use about an inch of rock. For large containers, you might need a thicker layer of rock. The purpose of the gravel is to provide an area for excess water to collect under the soil since it cannot drain from the container. The gravel mimics bedrock in the environment.

If you’re using activated charcoal in the terrarium, place a thin layer of it across the top of the gravel. It is not essential, but it works as a filter for any odor that might develop from standing water in the bottom of the terrarium. Check local garden centers and pet stores for this material.

Next, pour some of the potting media into a bowl, bucket or pan. Add a small amount of water and mix it in, breaking up any clumps. At optimal moisture, the potting mix will hold together in a ball without water dripping from it. Add water in small amounts and mix until you reach this point. If the mix is too wet, add more dry mix or allow it to dry to the optimal level before using.

Put the moistened potting media into the terrarium container on top of the gravel and/or charcoal. For the 2-liter bottle example, use 3 to 4 inches of potting media. For larger or smaller containers, adjust appropriately. Use enough potting media to provide adequate space for plant roots. Shake or tap the container gently to help the potting media settle without being packed or compacted.

Now the terrarium is ready for planting. For a 2-liter bottle, one or two small tropical plants are enough. Smaller terrariums might only hold one plant. Larger terrariums can hold more plants as size allows.

A few suggestions for plants are artillery plant, cacti, dwarf jade, false aralia, miniature ferns, miniature peperomias, polka dot plant, prayer plant, strawberry begonia and succulents. Be sure to use special potting media for cacti and succulents if using them.

Decorative rocks, sculptures or other garden decor can also be added at this point.

When you’re done planting and decorating, replace the lid or tape the bottle back together. Move the container to a location with bright indirect light.

Within the terrarium, water will evaporate from potting media and be released from plants. It will be visible as condensation on the top and sides of the container. Then it drips or rains back down onto the plants just as water cycles in the natural environment.

If the sides of the terrarium are constantly wet, open the container to allow some moisture to escape. If condensate does not appear over time, add a little water. When plants outgrow the space, open the terrarium to trim or divide them.

Terraria can house animals, as well, but these instructions focus only on terrarium gardens. If you’re interested in keeping frogs or other animals in this sort of environment, you’ll need to do more research on how to create a good habitat for them.


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