A federal magistrate in Denver also ordered brothers Eric and Ryan Jensen to each pay $150,000 in restitution and perform 100 hours of community service. Each read an apologetic statement but didn't show any emotion during the hearing.
The U.S. Food and Drug Administration has said the rare move to charge the Jensens was intended to send a message to food producers in the wake of the deadliest case of foodborne illness in the nation in a quarter century.
The outbreak caused 33 deaths and sickened 147 people in 28 states.
The Jensens pleaded guilty last year to counts of introducing adulterated food into interstate commerce.
Relatives of seven people killed in the outbreak testified during the sentencing hearing, with some asking for probation and others asking for prison time for the brothers.
They could have faced up to six years in prison and $1.5 million in fines.
Magistrate Judge Michael E. Hegarty said he did not order prison time or fines against the brothers so they could keep working to support their own families and pay restitution.
Federal investigators said the melons likely were contaminated in the farm's packing house because of dirty water on the floor and old, hard-to-clean equipment.
The Jensens have said their operation was given a "superior" rating just a month before the outbreak by their independent auditors, whom they are now suing.
Attorney William Marler, who represents relatives of 24 people who died from the outbreak, also has said probation is adequate. He said farmers, retailers and the federal government learned valuable lessons and there are now new regulations in place that will reduce the likelihood of a repeat tragedy.
The Jensens also argued probation would allow them to try to raise more money for restitution. Attorneys say the two men have already filed bankruptcy that provided nearly $4 million to victims and their families. Marler and other attorneys are suing retailers and auditors involved in the case after a bankruptcy judge estimated damages at $50 million.
Lawyers for the two men have said their guilty pleas do not imply any intentional wrongdoing or knowledge that the cantaloupes were contaminated.