The Uva Halpewaththa Tea Factory, 5km north of Ella, runs some of the better tea plantation tours in Sri Lanka. After you've enriched yourself with knowledge, treat your taste buds by trying samples of the estate's different teas. There's also a small shop selling leaves and tea-related paraphernalia. Tours take place throughout the day, but the frequency of tours varies slightly depending on the kind of tea being processed. To be safe, visit in the morning.
To get here, catch a bus towards Bandarawela, get off at Kumbawela junction, and flag a bus going towards Badulla. Get off just after the 27km post, near the Halpe Temple. From here you have a very steep 2km walk to the factory. A three-wheeler from Ella will charge Rs 1000 return.