The food industry has long realized that growing food in controlled environments is essential to supplement food supplies. There are some countries who have adapted well to the growing of food under cover of glass or poly tunnel and it’s these countries which have increased their own food supply to a level which enables them to support their own population and export the rest.
Over 90% of plants which are raised worldwide are grown in open fields. Over the centuries man has had to cope with the ever-changing environment and there still remains some regions where the climatic conditions and the substrata are adverse to the growth of crops. To counter this man has developed technological means to protect crops from excessive heat and cold and other negative climatic conditions.
The use of greenhouses and poly tunnels has increased exponentially over the last couple of decades as they provide favorable climatic conditions in which to grow crops. In effect they allow man to completely control the environment, protecting crops from adverse climatic conditions such as:
o Excessive precipitation or drought
o Excessive radiation
o Extremes in temperature
o Insect damage
A micro climate can be created for plants grown under cover which perfectly matches the conditions under which they best grow.
Some of the advantages of growing crops in a controlled micro climate, such as a climate created in a greenhouse or a poly tunnel include:
Advantages of poly tunnels
1. Yields can be increased dramatically depending on the type of crop and the control facilities used
2. Poly tunnels are ideally suited to flower crops and vegetable crops
3. Year-round production of some crops
4. Crop reliability increases
5. Production of vegetables and fruit out of season
6. Genetically superior plants can be produced which are disease-free
7. The use of pesticides and chemicals can be controlled
8. Water usage can be controlled
9. Tender plants can be hardened off easily
10. Increase in quality of crops
11. Possibility of hydroponic and aeroponic cultivation
he Netherlands has perhaps the most advanced greenhouse/poly tunnel industry in the world with just under 90,000 ha of growing space under cover. The Dutch insure relies heavily on this method of crop/flower production due to the cloudy conditions the county has to cope with.
Other European countries are also not far behind the Dutch with Spain and Italy also using this method of crop cultivation to produce goods out of season. Spain grows most of its vegetable crops under cover with watermelons, strawberries, cucumbers, beans, capsicums and tomatoes all produced in this way.
Due to Spain’s helpful growing conditions, most of their crop production is done in simple polytunnels which don’t require any sort of elaborate climatic controlled conditions.
Crop production under glass or polytunnel is also becoming popular in Asia, with China and Japan fast becoming world leaders in undercover crop production. Production in China has grown rapidly over the last few years and have over 50,000 ha of land covered by greenhouses, with over 10,000 ha alone producing fruits such as grapes, cherries, lemons and mangoes. In countries such as the Philippines crops which are grown under cover are not done so because they need extra heat, they are grown under cover to protect against excessive rainfall.
Gary Dolan grows his own produce on his allotment in Cheshire. He bought his polytunnel from First Tunnels.