A greenhouse or glasshouse is a structure in which generally plants are grown. It ranges in size from a small shelter to a large building.
Different materials, such as glass or plastic, are normally used for the roof and the walls. Incoming sunshine is heating the interior where some of the energy can be trapped.
Temperature and humidity inside a greenhouse can be controlled to create adequate and balanced conditions for plant growth. Thereby, infertile land can be turned into arable areas: plant production is improved and some crops can be grown throughout the year.
Proper ventilation is an important factor in the success of a greenhouse:
- Regulating the temperature
- Providing fresh air for photosynthesis
- Preventing pests
A greenhouse should get as much light as possible, except in a desert-like environment where too much light (irradiation) can be harmful for plant growth.
MY LIVING GREENHOUSE
Trying to take into account most of the factors above, I constructed a “living greenhouse” in the form of a conical “tipi” (teepee), planting branches (poles) of the Navajo willow (Globe willow) in my Belgian garden.
A tipi, used by some American nomadic tribes, is a conical tent traditionally made of wooden poles covered with animal skins. It provides warmth in winter, shelter during rains, and it is cool in the heat of summer. Tipis are disassembled when a tribe decides to move and reconstructed quickly when settling in a new area.
Contrary to these movable tents of the nomadic tribes, my “living greenhouse” is fixed on the spot, the willow poles having quickly rooted and ramified.
THE NAVAJO WILLOW
(Salix matsudana ‘Navajo’)
This round-headed, upright branching ‘Globe willow’ is related to the corkscrew willow (Salix matsudana ‘Tortuosa’). It is a hardy, large, deciduous tree, native to northeastern China, growing fast and reaching 15 meter (50 feet) in height.
In the southwestern United States, the ‘Navajo’ cultivar has been selected for its drought-tolerance and storm damage-resistance. It is adaptable to a wide range of soil conditions, even to the desert.
Particularly for that reason I used this lime green variety of the Globe Willow to construct my living greenhouse.
Semi-hardwood cuttings and hardwood cuttings are used for rapid propagation, e.g. in xeriscaping. I grew it from a small semi-hardwood cutting into a splendid 30 ft (9 meter) high, globe-shaped, upright branching tree in 9 years time. It is said to be a long-lived tree species It already resisted several years of winter frost in my own garden without any damage.
As it is possible to get willow poles easily rooting in the drylands, or even in a desert, one is in a position to create anywhere living tipis or tunnels in which:
- The sunlight will be filtered;
- There will be light shadow;
- There will be more humidity in the air;
- One could grow vegetables or saplings in such a tipi or tunnel.
Aiming at creating in the drylands shady spaces, to be used as a living greenhouse (or in which people could rest!), I have set up this experiment called “tipi living greenhouse”:
It convinced me that the Navajo willow merits full attention for its application potentials in all the drylands of this world.
With a minimal investment one could set up (ten) thousands of willow tipis or tunnels, thus offering people in drought-affected areas a chance to create shady spaces in which vegetables and tree saplings can be grown.
Who wouldn’t want to spend some time in such a mini-oasis ? Who wouldn’t be happy if aid organizations would start multiplying living greenhouses in all the drylands to combat desertification, to mitigate the effects of drought, to alleviate poverty?
That’s precisely what living greenhouses are meant for !
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