If the dispute is not resolved quickly, it could dash the country's hopes of increasing output to 10 million 60-kg bags this year, up from the 8 million in 2012.
Colombia's coffee farmers have seen their livelihoods shrink in recent years as the cost of fertilizers and other imports needed to produce coffee has chipped away at earnings, already reduced by low bean prices and the country's strong currency.
A strong currency hurts coffee growers and other exporters that receive dollars for sales but pay costs in pesos.
"We need earnings for coffee growers; we are broke," said Oscar Gutierrez, coordinator of a union that groups coffee growers in various Colombian provinces.
He said that while the strike goes on, farmers will not pick beans nor sell them.
Colombia, a top producer worldwide after Brazil, Vietnam and Indonesia, reported its lowest crop in three decades last year at 7.74 million sacks.
Since 2009, growers also have suffered from the impact of torrential rains that flooded soil and knocked beans from the trees. That later brought on disease that wiped out crops.
A tree renovation program - aimed at improving output in years to come - also took thousands of hectares out of production.
STRIKE UNJUST
"We are living in misery," said Teodulo Guzman, director of a private organization of coffee growers in southern Huila province.
"Right now, we don't have money to pay for coffee pickers, not even to fertilize. The secondary harvest looks good but it is going to get damaged because we don't have money to pick the beans."
In an early morning address, President Juan Manuel Santos called the strike "unjust" and said his government has done more to aid the sector than his predecessors, providing subsidies and cheap loans to help small-scale farmers.
Santos said the government has invested about 1 trillion pesos ($555 million) in the coffee sector since he took office in mid 2010 and called for strikers to reflect on that investment.
"This strike isn't just inconvenient and unnecessary, it's unjust," he said in a radio address as the strike kicked off.
A coffee grower gets around 550,000 Colombian pesos ($305) for a 125-kilogram sack, while production costs are 650,000 pesos for an efficient grower and as much as 700,000 pesos for regular ones, producers and exporters said.
The government provides a 60,000-peso subsidy for every 125 kg of coffee produced. A pound of Colombian coffee on international markets sells for $1.40, down from $2 a bag a year ago.
"We have tents and food to withstand a coffee strike that could last eight days," said Carlos Ocampo, who manages a workforce of 3,000 growers in the southern Valle del Cauca province.