Time for coffee and tea
Tea Growing - climatic requirements
It is very difficult to specify the ideal climate tea requires for good growth especially with regards to rainfall. Many attempts have been made, using many species, to measure the water lost in transpiration; these investigations have been carried out both in annual and perennial tea types with the hope of finding the ideal climatic conditions for tea growing. It is thought that the various species of tea do not have unique transpiration coefficients, and therefore the amount of transpiration that takes place is a relevance of weather conditions and soil types.
The kind of rain that falls is important in assessing the rainfall requirements of tea. Tea grown in the equatorial zones enjoys two rainy seasons; these coincide with the course of the sun across the tropical zones.
This means that regions in the North or South only get one passage and are therefore prone to long dry seasons. How the land is configured also has a large impact upon rainfall requirements. For example, Sri lanka is subjected to two prolonged rainy seasons, the north-east and southwest monsoons respectively, yet it has a rain shadow caused by the mountain massif. this deprives the eastern districts of the rains supplied by the south west monsoon. In as similar fashion the western ghats of south india are deprived of monsoon rains.
The elevation of prevailing temperatures has an important effect in modifying transpiration losses. The range in temperature of a particular region is affected by location, for instance an Oceanic area will have totally different temperature characteristic than a tea growing area located in continental climate. The elevation of the land also has a large impact upon the temperature climate of tea growth. Taken together the location and altitude can have a large affect upon temperature climate, for example, the upland districts of Sri Lanka have a similar temperature climate range to that of Highlands of Kenya, which are 450 metres higher in altitude.
There does not seem to be a decisive upper limit to the amount of rainfall under which tea will maintain a vigorous growth. In Sri Lanka certain areas receive as much as 5100 mm of rain yet tea does well. As regards the lower range it is thought that rainfall of less than 1300 mm per annum has a detrimental effect upon tea growth.