Eben Makonese, chief executive of Chemplex Coroporation which runs the three semi-governmental firms, said Dorowa minerals, Iron Duke and Zimphos have not been able to operate since last month.
"We have sent people on forced leave and on half pay because of these operational challenges," the Herald quoted him as saying.
The Dorowa mine, which produces phosphate rock concentrate, a key component in making fertilizer, ceased operations due to "persistent power cuts" and lack of foreign exchange to import mining materials, said Makonese.
Fertilizer firms have so far produced 160,000 tonnes against a target of 600,000 tonnes for the forthcoming season.
Misheck Kachere, another senior company official, said fertilizer has been sold at a fifth of the cost of production as a result of government price controls imposed two months ago.
He said a bag of 50 kilogramme of fertiliser was selling at 88,000 Zimbabwe dollars (352 US dollars at the official rate, but 44 US cents at the parallel m