What’s all the fuss about terrariums? Terrariums are mini masterpieces that you can enjoy throughout the year; they are easy to make and even easier to maintain. Terrariums make great office plants and can be made for birthday or valentine gifts or just as a way to brighten up someone’s day. In my (considerable) experience, there are just a few steadfast rules to follow for a long lasting ecosystem of your creation.
Before Getting Started
Consider the conditions of the location you want the terrarium to be in; most importantly the kind of light will it receive. If it is to be in a bright, sunny windowsill, you will want to select the appropriate plants for sun and avoid certain shapes of containers. If it is to be kept in a dimly lit room or well away from windows, a different selection of plants will thrive and certain shapes will work better than others.
Choosing a Container
- Your glass container can be tall or squat, and can have a lid or not, but it needs to be clear.
- Open container or closed, the size of the opening and neck influences the amount of air-flow inside container; a narrow opening stays moist and is better for mosses, where a wide-mouthed jar would dry out more quickly and be great for succulents. Open containers need more consistent moisture maintenance and watering; closed containers are less maintenance.
- Air-space or headroom inside container (above plants, once planted) should ideally be at least half of container or more.
Have These Tools on Hand
- Long tweezers make it much easier to work in the tight spaces of your glass vessel and are extra useful when handeling cacti
- Small scoops, funnel, and/or spoons to pour and place materials into small spaces
- Small brush to dust off wayward bits
- Spray bottle to clean glassware and water your finished creation
The Layers of a Terrarium
Rocks or Pebbles: Bottom layer of terrarium
Horticultural Charcoal: Sprinkle on top of the pebbles. A little charcoal goes a long way to filter air and water and prevent the terrarium environment from succumbing to moisture loving bacteria.
Sphagnum Moss: Acts as filter between soil & rock layer
Bonsai Soil Mix: This is my favorite indoor potting mix – period. It’s the perfect blend of organic matter (without adding unnecessary and often stinky manuers) with more sand and pumice than most potting blends to encourage good drainage without drying out too fast like cactus mix.
Plants: Do not crowd container; less is more. And remember, right plant, right place! For example, dwarf tropicals are much happier in a closed system (with a lid), and cacti are perfect for open air terrariums (no lid). Neither one requires a great botanist to keep content; they thrive on neglect and object to over watering more than anything. No-fuss tropicals include Red Star (Cryptanthus), Spikemoss, Button Fern, Baby Tears, and Pepperomia. Cacti are tough, but can be a little scary. Here are some tips to make them more user friendly. Protect your hands with gloves, protect the cactus spines by using a sponge, or avoid spines altogether by selecting a spineless variety!
Top Dressing: Smaller rock size is key to achieve a nice layer; I like to use a neutral rock as a base coat then accent with a few larger sizes and party rocks. Party rocks are actually small pieces of tumbled glass that we carry in a great array of colors (beach, ocean, amethyst, forest, candy).
Personality: Include something to your new planting that makes you smile; a rock from a favorite hike, a twig out of the garden, a miniature figurine to add a bit of whimsy. Whatever it may be, it’s a great way to personalize your creation!
Balancing light and moisture is key. Make sure that the plants you use get the care and conditions they need. Shade plants will need less water than sun-loving ones, while mosses and ferns prefer more constant moisture. Most closed terrariums will be happy with a misting every one or two weeks, where succulents or dry plantings should probably be watered lightly every two weeks or so. If your open terrarium seems to be drying out, but you can see water in the bottom rock layer, try covering or closing your container for a day or two to redistribute the moisture (even if you have to use clear, plastic cling-wrap). This works well for newly planted projects that have yet to fully develop new roots.
Some great beginner terrarium plants for sun:
- Dwarf boxwood
- Brass buttons: leptinella
- Creeping fig
- Sweet-flag: Acorus
Some great beginner terrarium plants for shade:
- Krauss’ Spikemoss
- Irish/Scotch moss
- Ferns, especially asparagus fern
- Golden baby tears
- Dwarf mondo grass
Other plants great for advanced terrariums in part-sun/part-shade:
- Bromeliads, epiphytes, and tillandsias (air plants)
- Haworthia (light shade)
- Jade plants
- Carnivorous plants: pitcher plants, Venus flytraps, sundews