The tea plant (camellia sinensis) like most other plants originates from seeds. Only 1-2% of tea plants tend to grow these seeds, hence its always a race to find the best seeds from the best clones of tea.
The seeds are very fragile and therefore need to be taken care of as soon as they are plucked. Most esteemed tea farms have their own nurseries where the seeds are properly taken care of in a controlled environment.
Immediately after plucking the seeds, they are kept in a dark environment for almost a week after which they are transferred into saplings. The saplings are then nurtured in the nursery for almost 18-24 months and then planted on the farm.
The first leaves from the new plant will be plucked 1-1.5 years after being planted on the farm. At anytime, a healthy farm will have 1-2% of the farm always under re-plantation (to weave out the old plants and make way for the new ones).