Chicfarm: www.chicfarm.org: Bottle garden of your choices

Thriving since 1960, a garden in a bottle: Seedling sealed in its own ecosystem and watered just once in 53 years. David Latimer first planted his bottle garden in 1960 and last watered it in 1972 before tightly sealing it shut 'as an experiment' The hardy spiderworts plant inside has grown to fill the 10-gallon container by surviving entirely on recycled air, nutrients and water. Gardeners' Question Time expert says it is 'a great example just how pioneering plants can be'

For the last 40 years it has been completely sealed from the outside world. But the indoor variety of spiderworts (or Tradescantia, to give the plant species its scientific Latin name) within has thrived, filling its globular bottle home with healthy foliage.

Mr Latimer, 80, said: ‘It’s 6ft from a window so gets a bit of sunlight. It grows towards the light so it gets turned round every so often so it grows evenly. ‘Otherwise, it’s the definition of low-maintenance. I’ve never pruned it, it just seems to have grown to the limits of the bottle.’ The bottle garden has created its own miniature ecosystem. Despite being cut off from the outside world, because it is still absorbing light it can photosynthesise, the process by which plants convert sunlight into the energy they need to grow.

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, 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 absorbs the plant's waste oxygen and releasing 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 plants’ roots, is released into the air during transpiration, condenses down into the potting mixture, where the cycle begins again.

Photosynthesis creates oxygen and also puts more moisture in the air. The moisture builds up inside the bottle and ‘rains’ back down on the plant. The leaves it drops rot at the bottom of the bottle, creating the carbon dioxide also needed for photosynthesis and nutrients which it absorbs through its roots.

Water with extreme care (your jar won't need much) and place the finished mini garden in a well-lit spot, but not on a hot south-facing windowsill. Into a cleaned out ten gallon carboy, or globular bottle, which once contained sulphuric acid, he poured some compost then carefully lowered in a seedling using a piece of wire.

He put in about a quarter of a pint of water. It was not until 1972 that he gave it another ‘drink’. After that, he greased the bung so it wedged in tightly... and has not watered it since. The bottle stands on display under the stairs in the hallway of his home in Cranleigh, Surrey, the same spot it has occupied for 27 years after he and his wife Gretchen moved from Lancashire when he retired as an electrical engineer.

He added that this process is one reason why NASA was interested in taking plants into space.‘The only input to this whole process has been solar energy, that’s the thing it has needed to keep it going. Everything else, every other thing in there has been recycled. That’s fantastic.’

If you can’t see the point, you can’t smell it, nor eating it. You can try to have a cola bottle short-term garden instead.