NAIROBI (Reuters) - Kenya's earnings from horticultural exports rose by 6 percent in 2013 helped by bigger orders and recovering from a drop the previous year, a senior official in the agriculture ministry said on Tuesday. Horticulture is a leading source of foreign exchange for east Africa's biggest economy alongside tea exports and tourism and agriculture accounts for about a quarter of Kenya's gross domestic product. Kenya has yet to release full-year economic growth for 2013 but it is estimated at 5.0 percent. The country exports most of its horticultural produce to Europe, where officials are optimistic of a better performance this year due to an improving economic outlook. Kenya earned 93 billion shillings from the cultivation of fruit, vegetables, flowers and nuts last year, up from 87.71 billion in 2012, Agriculture Principal Secretary Sicily Kariuki told Reuters. The volume of horticultural exports rose to 477,000 tonnes versus 380,421 tonnes in 2012, statistics from the ministry showed. Earnings from horticulture had fallen 3.8 percent in 2012 to 87.71 billion shillings, with exports dropping to 380,421 tonnes from 380,848 tonnes in 2011. A stable foreign exchange rate and projected favourable weather conditions are expected to boost the sector's performance in the short term, the official said. Kenya has maintained a relatively stable exchange rate since 2012, after it raised lending rates to tackle high inflation and market volatility. The central bank held its benchmark lending rate at 8.50 percent this month for the fifth policy meeting in a row, citing price stability. Rainfall during the long rainy season starting this month is expected to be near-normal and well distributed, presenting a bright outlook for the country's mainly rain-based agriculture. A Reuters poll forecast Kenya's economy would grow 5.5 percent this year.