A conservatory terrarium is much like a traditional terrarium – a tiny garden under glass – but is easier to create and maintain because of the structure it lives within.
The concept is the same. The enclosed environment creates a self-sustaining ecosystem, but in a mini-conservatory you can pot your plants in their own individual containers (easier than planting a whole terrarium) and group them in the container. This allows you to easily swap them out or prune them when they get too big. You can also plant a single container, as in this example, and then insert it into the conservatory, which makes the planting process more manageable.
Finding a conservatory is the first step. They seem to be everywhere these days. Check your local garden retailers, home décor stores and online. Search under conservatories, terrariums, and Wardian cases. The secret to a successful, self-sustaining terrarium is to create enough of an enclosed environment that sufficient moisture collects within to water the plants. A benchmark to look for is to have beads of water collect consistently, but not to the point that they run in streams down the side of the glass or drip excessively. Most conservatories have a top that opens… prop it up an inch when this happens. Because many conservatories are larger and have more air space, you may have to supplement watering more than with a traditional terrarium. Keep an eye on the beads of water to know. And never fertilize plants in a terrarium… you actually want to discourage growth.
Terrarium plant closeup with orchid, pilea, dracaena, begonia and fern.
Stones, charcoal, moss, soil. From the bottom up, this is how to layer your terrarium planting base. The stones will provide drainage, but if you are planting in containers with built-in drainage, you can skip this step. The horticultural charcoal keeps the conservatory smelling fresh and also keeps fungus at bay, so it’s a good inclusion in an enclosed environment. The moss prevents the soil from washing down through the other layers. Strive for an inch or so of each of these layers and as much soil as you need to accommodate your plants…from two to three inches. Don’t use a soil with fertilizer incorporated into it.
The right plant for the job. Because terrarium gardens are hot right now you see a lot of them and many have plants that will never work in this type of environment. Succulents, though lovely, are not the right choice! Plants that are tolerant of a moist environment and moderate shade are what thrive. I have had success with these: ferns, peperomia, baby’s tears, hypoestes, nephthytis, prayer plant, pilea, dracaena, and begonias. Orchids do well in a terrarium and can be kept for their interesting leaves after blooming. Pothos and philodendrons also do well, but be ready to deal with their aggressive nature. You will either need to prune them or be pleased with the nest of foliage they produce.
Terrariums do best in bright, indirect light. Though they are self-sufficient, they are not without some maintenance. As mentioned, supplemental watering will likely be needed on occasion, even in tightly planted vessels. Again, monitor the condensation. Occasional pruning and thinning will also be needed but most likely only every two years or so. They are long-living indoor gardens that can be with you a lifetime when you plant and tend them thoughtfully.
This article ran in my DIY column in Northern Gardener magazine.