Gardening under glass

Terrariums provide indoor greenery for any space


With winter approaching, indoor plants are a great way to have some greenery in your life, even if the weather is bleak. Terrariums, glass containers with soil and plants, are an excellent way to have a garden even in the tiniest, overpriced apartments. Terrariums can create a high-humidity environment that many tropical plants need to thrive. While they may seem intimidating to own and maintain, they are low-maintenance if you choose the right plants.

The terrarium and the plant material that you decide to use will be a large deciding factor for how to maintain it. Terrariums can either have a sealed or unsealed bottom as well as having an open or enclosed top. Unsealed bottoms will leak, so you will have to water your terrarium in a sink to prevent a mess on your table or desk. Sealed bottoms won’t leak, but you will have to be careful when watering as well to prevent flooding. With open top terrariums you won’t need to worry as much about plant height as in an enclosed one.

When deciding what plants to use, it’s best to choose plants that prefer similar conditions to ensure that everything thrives. Spike moss, ferns, begonias, and calatheas work great in low light. If you are planning to place your terrarium in a room with a lot of light, succulents will work with a well-drained soil mix — just be aware that you will need to water much less than a tropical terrarium.

When planting, place about a half-inch of soil in the bottom of the container to ensure the plant roots have soil to grow into. Place your plants and then fill in with soil. You should fill less than half of the terrarium space so there is as much space for the plants as possible. You can place a top layer of gravel or moss for an aesthetically pleasing cover. I also enjoy using twigs, stones and figurines for a personal touch.

Maintenance can be tricky for those who continually like to do things with their plants. Over-watering is one of the greatest killers of houseplants, so one must resist the temptation of watering constantly. It can take weeks before a terrarium dries out and requires watering. An advantage of a terrarium is that you can see how wet the soil is. Always check the soil before watering. You can stick your finger about an inch into the soil and feel how moist it is. After watering keep the terrarium door open, to allow air circulation for one day. You can provide supplemental mist every couple of days if you have that burning desire to do something to your plants.

With many people living in Denver without a garden, a terrarium is a great way to foster a budding horticultural talent. Terrariums allow people to grow plants that don’t do well outside in Colorado and they are guaranteed to liven up any bland office or living space.

Nicholas Giaquinto is a conservatory horticulturist at the Denver Botanic Gardens. He can be reached at


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