By Tonya Ashworth, Extension Agent
Right now, my plants outside look a bit sad. But, like many gardeners, I can’t go for too long without getting some dirt under my fingernails. So, to pass the time as we wait for spring, we turn our attention indoors. Houseplants have been around since the Victorian era bringing some life inside our homes as we wait out the winter. Check out Walter Bryant’s recent article on boosting the humidity for houseplants.
Terrariums are a good way to get creative with interior plants and make a cool centerpiece for your coffee table. They were accidental invented by London surgeon Nathaniel Ward in 1830. Dr. Ward was originally interested in entomology as a hobby. So, when he found a hawk moth pupa, he brought it home and put it in a sealed glass bottle along with some damp soil to watch it transform. After 6 months had passed, a fern had started to grow in the bottle and the first terrarium was born. This might not seem like a big deal to us now, but it was a major advancement in horticulture at the time. Dr. Ward wrote a paper on his discovery, and miniature greenhouses called Wardian Cases were built and used in the nursery trade. These forerunners to the humble terrarium allowed plants collected from the wild in places like Australia to survive an eight month or so journey at sea and arrive safely in London. This was such a big deal that Dr. Ward’s original bottle was displayed in 1851 at the World’s Fair.
How to Do A Terrarium
Now you can create your own relic of the Victorian era. Just about any container will work, so long as it is clear. Try canisters, candy jars, or anything with a lid for a traditional terrarium. A simple goldfish bowl or other glass container can be used for an open-air terrarium.
Since there are no drainage holes, getting the soil and water right is important. For open or enclosed terrariums, creating a layer for drainage can help keep plants from rotting. The first layer in should be fine gravel. Fish aquarium gravel works great. I prefer the natural-colored, but you can use hot pink if you are feeling fun. The next layer should be about ½” deep horticultural charcoal. This can be found online or at your local garden center. Before you add growing medium, layer in some sort of barrier to keep the charcoal and gravel from getting all mixed in with the soil. I like to use a layer of sheet moss or sphagnum moss. I have read that a small piece of landscape fabric or a thin screen material will also do. After your drainage layers are in, add moist potting soil. You want the soil to be damp enough so that when you squeeze it, it kind of sticks together but water doesn’t pour out.
Time to plant it up. Choose at least 3 plants of varying growth habits, colors, or textures to make it visually appealing. Buy the plants small, in 2 or 3” size pots. The most important thing about plant selection is that all the plants need to have similar moisture requirements. Don’t mix tropicals with cacti, for instance. Also, choose plants that have a dwarf growth habit, so they don’t outgrow the container too quickly. Long-term, you can prune to keep them in bounds if necessary. Make sure the root balls of the plants are moist before you put them in, and mist with water to get the soil off the leaves after planting. Finally, I like to add some interest to the composition by placing a cool-looking rock or a bit of reindeer moss or perhaps a small cone or twig to the soil surface. If you are making this into a project for a child, pair that hot pink fish gravel with a tiny unicorn toy or maybe use neon yellow gravel and a small dino.
For an enclosed terrarium, mist the inside with water and then seal it up. Keep in mind that it can take up to 6 months for the rain cycle to really get going. If you have too much condensation forming inside the container, just take the lid off for a while and let it evaporate.
With the open-air terrariums, getting your watering right is key. Use your finger to check how moist the soil is and only water as needed. Water a little at a time. You don’t want the soil to become saturated and not be able to drain. Don’t fertilize the first year, as you want the plants to grow slowly. If you do eventually fertilize, use a houseplant fertilizer at half the recommended rate on the bottle.
If you have never put together a terrarium before, you should give it a try. While you are at it, might as well make 2 so you can give one as a gift or take it to your office. For more info about growing plants indoors, go to our Ask IFAS website and type in your question.
This article appeared in the Florida Times Union and has been slightly modified per UF Communications Department Guidelines.