"As a further precaution, Southern Fresh has made the decision to place all washed salad products in the marketplace on hold until testing confirms that it is 100 per cent safe to eat. These results are expected to be available on Friday, April 15, in the afternoon at the earliest," said Southern Fresh Group general manager Jeremy Dunn.
"It is important to note that there have been no notified cases of Listeria illness from eating these salads. We are taking these precautionary steps to proactively protect our consumers.
"Our other lines, including herbs and baby vegetables, are unaffected by this issue and are available for dispatch as usual."
Southern Fresh would take "all necessary steps" to ensure its produce was safe to eat, Mr Dunn said.
A My Food Bag statement to clients said of the spinach: "Erring on the side of caution, we ask you to discard the spinach. If you have already consumed it and feel unwell please contact your doctor."
The voluntary recall affected its customers in Wellington, Palmerston North, Hawkes Bay, Taranaki, Kapiti Coast, Nelson, Christchurch and Dunedin.
Auckland, Whangarei, Rotorua, Taupo, Bay of Plenty and Waikato customers are not affected.
My Food Bag will provide a $10 credit to customers affected.
