A well-drained highland is suitable for tea cultivation. Waterlogging, heavy soil erosion, drought and land slides create great problems in tea cultivation. Tea can be cultivated in the areas where the slope is up to 50 percent .However, in areas where the slope is more than 2 percent, contour planting and contour drainage should be followed. Tea can successfully be cultivated in altitudes up to 2500 m above the mean sea level. At higher elevations, the air temperature falls at the rate of 2oC with increase in elevation by 300 m. The growth of tea plants at higher elevation is slow. In hilly areas, special care should be taken while cultivating tea in the southern aspects.
Plant and Soil Indicators
The suitability of an area for tea cultivation can be judged from the existing vegetation. This is important for planting tea in non-traditional areas. The plant and soil indicators can provide some guidance in selecting lands suitable for tea cultivation.
- Albizzias are reliable indicators of land suitable for tea. The area is suitable where Albizzia species form a part of the natural vegetation.
- Braken has long been recognised as an indicator plant in Sri Lanka and South India. The fernGleichnia is also regarded as an indicator.
- Aluminium accumulator plants of the families of Melastomaceae and Rubiaceae can provide some information about the tea soil. Melastoma malabathricum, a shrub bearing pink coloured flowers in an indicator plant which grows abundantly in tea growing areas of Assam.
- One species of the family, Rubiaceae (Craterisperum lauinum) is reported to have been a decisive factor in the choice of a site in Uganda for cultivation of tea.
- The forest with deep rooted trees indicates well depth soil which is suitable for tea growing.
- Red soil as found in Java, Sri Lanka, parts of China and N.E. India are considered to be suitable for tea. However,soil colour may not indicate the suitability of soil for tea.