If allowed to grow wild and unattended, tea plants would reach the height of large shrubs. To make harvesting easier and to improve yields (the production of pluckable, two leaves and a bud) the tea bushes are regularly pruned and shaped into flat-topped bushes of about three feet in height. Plants are placed in rows with standard spacing being 105cm x 60 cm apart. Shade trees are planted between the rows with standard spacing being 40ft x 40ft to protect the plants against intense heat. In Assam two leaves and a bud are harvested from the bushes at 7 day intervals. Tea harvesting is exhaustive and labour-intensive and is a procedure of considerable skill. Tea pluckers, traditionally women, learn to recognise the leaves which are ready to be harvested by experience. This is important because if the leaves are left to grow beyong their optimum growth period of 7 days, the leaves will harden. The tea made from these hardened leaves will not have the required liquoring charecteristics (briskness, brightness and body) and will produce inferior tea.