A moss landscape under glass: open and closed terraria
A botanical terrarium is a glass vessel containing one or more plants. The history of plant terraria began in Victorian England. Then, the physician Nathaniel Bagshaw Ward (1791– 1868) discovered that transporting medicinal and exotic plants by ship became easier when the plants were kept in glass containers that protected them from wind and changing temperatures. With the use of Ward’s vessels, plants could be successfully transported between remote countries.
There are two different types of plant terrarium: open and closed. The plants in a closed terrarium cycle their moisture and nutrition, and the humidity of the air under the glass is high. An open terrarium can be used for plants that require an even temperature but which can cope with a drier atmosphere. Mosses benefit greatly from being grown in either kind of terrarium because of the humidity created under the glass.
In these open plant terraria I have used the flowering plants Pulsatilla vulgaris and Rex begonia, the grass Carex brunnea and the Cypress-leaved plait- moss (Hypnum cupressiforme).
Materials and tools needed
• Glass bowl, or if you don't have one, a jar or glass
• Water-retaining granules
• Plants such as Pulsatilla vulgaris (Pasqueflower), Rex begonia (Begonia), Carex brunnea (Sedge) and Cypress-leaved plait-moss (Moss)
• Spray bottle
An open terrarium should be watered twice a week and the moss may need to be sprayed daily. Use a pipette to water the soil under the moss. You will know whether the soil is moist by weighing the terrarium in your hands before and after watering. The terrarium will feel significantly heavier when the soil is moist.
Place the terrarium in a spot that gets only indirect sunlight. Keep in mind that glass can get very hot if it is near a sunny window, so move the terrarium further into the room during the summer. If the light comes from only one direction, rotate the glass periodically to allow light to reach all plants inside.
How to make it
1. If the plants are relatively small you do not need to remove more than possibly the top layer of loose soil when lifting them out of their pots. Clean the tops of the moss pieces you want to use in the terrarium and remove any old moss from the underside. Keep a little of the soil layer if you picked the moss outdoors.
2. Pour water-retaining granules to a depth of a few centimetres into the bottom of the container. Make sure the layer covers the entire area you plan to plant.
3. Mix a little perlite into some potting compost and pour about 10cm of the mixture over the water-retaining granules and flatten to level the surface.
4. Position the plants and rearrange them until you find a composition you like. Turn the glass to check that their positions look good when viewed from all directions. Push down the clusters of plants into the new soil layer.
5. When all the plants are in place, fill up with more of the soil mixture and mould the soil to get the shape you want. Water with a spray bottle.
6. Add stones and any gravel you want in the terrarium. Push the stones slightly into the soil so that they are held in place.
7. Place your moss pieces on the soil. Use a stick to poke the edges of the moss under the stones. Press the moss down so that it has good contact with the surface.
8. Check to make sure the landscape looks good from all directions and spray the moss again with water.
Tend and trim any plants that begin to grow out of the vessel. After a while, the inside of the glass can become dirty and may need to be cleaned. If you have difficulty accessing the inside of the glass, you can tape a loop of paper towel on to a stick, to help you reach difficult areas.
In the end, by trying to create small moss landscapes, maybe we are mimicking and creating the great outdoor landscape to care for and admire in our homes.