Polar vortex is a term that most of us had never heard until this winter. I live in the Midwest, and at this point, we’re sick of hearing about it! The swirling snow and cutting wind are brutal, and every aspect of our lives has to be adjusted to deal with the intense cold. Indoor plants are no exception, and my way of handling them during the freezing winter months is to scale down my operation. I’m thinking small. Terrariums are a great way to add plant life to your indoor environment on a really small scale. They look great anywhere in your house, take up little space, and make great gifts. Building them can be a way to flex your creativity, as well. You can buy a kit to build a terrarium, or purchase the plants and substrate ingredients separately. You can also purchase completed terrariums, but where’s the fun in that? You could say the terrarium was the grandfather of indoor gardening. The original terrarium was the Wardian case. During the height of British colonial rule, exotic botanical specimens were in high demand. Many species of flora and fauna were brought back from far-flung locales to delight the British upper crust. Unfortunately, many of the plants and creatures were unable to survive the cold English winters. Greenhouses eventually became popular, but even these structures left plants vulnerable to Britain’s high level of coal smoke. Dr. Nathaniel Bagshaw Ward was a physician and garden hobbyist who found that enclosing ferns in small glass containers allowed the plants to flourish in protected air space. Pretty soon, Dr. Ward was commissioning larger cases made specifically to fit into the cargo holds of ships. These Wardian cases enabled travelers to ensure the survival of exotic species making the overseas trip with them back to England. Today, intricately framed Wardian cases are pricey, but a simpler terrarium can be made out of most any glass container, from an old jar to a blown glass globe. There are a few guidelines to remember when building a terrarium. The first is drainage. By definition, a terrarium is a closed glass container. This means that any moisture you add isn’t going anywhere. You must be careful to allow for drainage away from the roots of the plants. Adding an inch or two of clay pebbles at the bottom of the container will ensure that any unused moisture can collect harmlessly around them, instead of sitting around the roots of your plants, causing rot or mold. I prefer to use soaked coco coir bricks on top of the pebbles. They are free of pathogens, have a neutral pH, have a nice, natural color and are decay resistant. Water lightly! Since evaporation isn’t much of an issue, you won’t have to compensate for it. A terrarium is an enclosed water system, just like earth’s atmosphere, so any water that does evaporate will just condense and fall once more. You can assume that whatever water you put into the container will be used by your plants. Any excess could pose problems. As such, be a water miser. Be picky with your plant selections. Some plants are more suited to this space than others. You want something that isn’t going to grow fast and large—ask me how I know. I made a terrarium out of a wine decanter last year and put a single cloned pothos cutting into it. Now you can’t even see the decanter—the pothos has completely taken over. A quick internet search will lead you to tried and true plant varieties for terrariums, species that are by nature smaller and slow growing. I like to start my plants with a little room to grow, so they can fill the space in without crowding each other. If you use containers that are open on top, it will give you a little leeway with water needs, since there will be a bit of evaporation. Open containers are the best choice for cacti and succulents for this reason. You can incorporate your own style and/or interests into your terrarium, or one you make for a friend. Add some funky antique kitchen tools for a chef friend, or dice and poker chips for a gambler. You could do a tiny terrarium in a glass cup for your favorite caffeine addict. Whatever your approach, be creative and have fun!