Going to a place in Darjeeling and not seeing a tea estate will leave you trip incomplete. Mirik is full of valley covered in tea bushes. Almost throughout the year, you can see workers picking ripe leaves or watering the bushes.
The most fascinating thing about them is that you can walk though the gardens, that is if you don't damage the bushes, with thee bushes growing on either side. Spending an hour or two here will make the rest of your day.