United Nations agencies estimate up to 1.4 million Haitians need food help after Hurricane Matthew struck in mid-October, with 800,000 of those in dire need.
The Category 4 storm devastated fields, fruit orchards and food stocks and wiped out fishing operations in the worst-hit areas.
With existing local produce quickly running out, the Food and Agriculture Organization has appealed for more funding.
"If we don't act now to provide them with seed, fertilizer, and other materials they need, they will not be able to plant and will be faced with persisting food insecurity," Nathanaël Hishamunda, the FAO's Representative in Haiti, said in a release.
The worst-hit areas were Grand'Anse and Sud in the country's south, where 60 to 90 percent of all crops were destroyed.
The FAO estimates an additional $56 million is needed to stave off famine over the next three months.
The official death toll is more than 540, but local officials have reported more than double that number were killed.
The 2016 Global Hunger Index said that even before Matthew's destruction, more than half Haiti's 10 million population were undernourished.