Tesco claimed last week that its earliest ever crop of Jersey Royals had gone into its Kensington store, selling loose for £2.99/kg. The potatoes are not usually available until mid-March.
Asda, meanwhile, said its own Jersey Royals, which also went into stores last week, are eight weeks earlier than usual and will be priced competitively in the Extra Special range.
"We are proud to have Extra Special Jersey Royals on our shelves at the very start of the season, earlier than ever before," said buyer Des Wilson.
Sainsbury's is expecting to have the potatoes in store from 13 March and the supermarket is claiming its new supply chain, which gets most produce from soil to store within 24 hours, means it can offer the freshest potatoes yet.
It added it was the only one of the big four to wash and pack on the island.