Here is the result of something English garden enthusiast, David Latimer did more than 55 years ago:
In 1960 he planted a single spiderwort seedling in some composted soil in this terrarium bottle, watered it and put a cork in the top. In 1972 he poured in a little more water and replaced the cork. That's it! Other than those actions and placing the bottle in a sunny spot, he just watched what happened. The little plant, using photosynthesis created its own balanced biosystem and thrived. It watered itself, fertilized itself and grew and grew.
HOW THE BOTTLE GARDEN GROWS
Bottle gardens work because their sealed space creates an entirely self-sufficient ecosystem in which plants can survive by using photosynthesis to recycle nutrients. The only external input needed to keep the plant going is light, since this provides it with the energy it needs to create its own food and continue to grow.
Light shining on the leaves of the plant is absorbed by proteins containing chlorophylls (a green pigment). Some of that light energy is stored in the form of adenosine triphosphate (ATP), a molecule that stores energy. The rest is used to remove electrons from the water being absorbed from the soil through the plant's roots. These electrons then become 'free' - and are used in chemical reactions that convert carbon dioxide into carbohydrates, releasing oxygen.
This photosynthesis process is the opposite of the cellular respiration that occurs in other organisms, including humans, where carbohydrates containing energy react with oxygen to produce carbon dioxide and water and release chemical energy.
But the eco-system also uses cellular respiration to break down decaying material shed by the plant. In this part of the process, bacteria inside the soil of the bottle garden absorb the plant's waste oxygen and release carbon dioxide which the growing plant can reuse.
And, of course, at night, when there is no sunlight to drive photosynthesis, the plant will also use cellular respiration to keep itself alive by breaking down the stored nutrients.
Because the bottle garden is a closed environment, that means its water cycle is also a self-contained process. The water in the bottle gets taken up by plant's roots, is released into the air during transpiration, condenses down into the potting mixture, where the cycle begins again.
I recently read Tracy Chevalier's The Edge of the Orchard, a wonderful fictional account of 19th-century settlers in Ohio who had a passion for apples. In this book, you will learn more about apples than you even knew existed.
In fact, I learned a lot about trees in general and about the harvesting of seeds and seedlings for transport overseas. The mid-19th century was the time of gathering North American botanical species of all kinds to ship to avid English gardeners, especially redwood seedlings which were sent to Wales for a wealthy landowner who wanted these magnificent trees on his estate (still to be seen at Penryn Castle).
One of the ways of shipping young seedlings, described in Chevalier's novel, was in a Ward's case: a construction of wood and glass that completely enclosed the seedling, protecting it from wind and salt spray. Once the seedling was planted and watered, it was encased in glass which then did not have to be opened during the journey, a trip lasting several months and requiring several legs by sea and by land: down the coast by ship from San Francisco, across the Panama isthmus by wagon, then up the east coast by ship to New York, and finally across by sea to Great Britain.
David Latimer's terrarium is essentially a Ward's or Wardian case, a remarkable accidental 1830's discovery by British surgeon, Dr. Nathaniel Ward, who encased a butterfly pupa in one, subsequently forgot about it for 6 months and then was stunned to discover a small fern growing alongside the dead pupa.