The profit growth was largely drive by Horana Plantations' rubber business with only marginal growth in profits from tea and other businesses.
Rubber prices shot up to record highs earlier this year on the back of soaring oil prices, but have plunged since then as the commodities bubble burst.
Rubber prices hit 400 rupees a kilo in June at the height of the bubble but crashed to less than 200 rupees in October.
According to results released by Horana Plantations, net profits in the first half ending September 30 were up 140 percent to 58 million rupees from a year ago.