In Thailand, Chiang Mai and Chiang Rai provinces are the largest area planted with tea, occupying over 80 percent of the total tea growing area.The other provinces that also plant tea but on small scale, are Nan, Phrae, Lampang, Tak and Mae Hong Son. The tea areas lie between 180 and 200 N latitudes at elevations ranging from 300 to 400 m for low land tea and from 700 to 1300 m for hill tea. There are two categories of indigenous tea that grow in the lowlands at altitudes of about 300-400 m under heavy shade representing a small proportion of the overall tea area.The main hill plantings are located in the altitude ranging from 700-1300 m. The hill tea is generally grown in remote areas on very steep slopes.
Tea grows wild as an under-storey shrub in the forests of the northern hills of Thailand. Tea has been cultivated in many places as beverage, chewing matter, food and drug for a long time. The traditional use of tea has been in the form of pickled tea or Miang, the market of which is confined to both the hill tribes and the local people of northern Thailand. The hill tribes grow tea in fields at relatively wide spacing without any pruning. The plants grow 3-5 m high and the green leaves are plucked by bending the branches. However, in the modern plantations, the plants are kept low by pruning.
Both Assam tea and China tea are grown. Tea in Thailand is a seasonal crop, the harvesting season is when the leaf grows from April until November. The bushes become dormant during the dry period from December to March. Plucking system and round vary from place to place. For miang processing, there are four plucking in the year.
The domestic product on which the tea industry was primarily based, is the pickling miang tea for home consumption and trade amongst the people of northern hills. However, demand for miang has declined now and the demand for green tea has grown up. The green tea is processed in small factories by procuring leaves from the factory owners’ own plantations or purchasing from the villagers. The green tea so processed are normally transferred or sold to central factories for re-processing and grading. There are three market outlets viz.,local sale in the northern province, sale to the main traders in Bankok and export.