Tree buyer Andy Bunker said usually 1-2 per cent of trees might drop needles and need replacing but this year it was up to five per cent.
He said trees had not "closed down" properly before harvesting and next weekend could bring more returns to garden centres.
He added: "It's been a real problem this year, but that's nature."
Buckingham Garden Centre's Chris Day said the mild weather means trees are dropping needles early, adding: "It's more woe that we have no control over."
British Christmas Tree Growers Association advisor Colin Palmer said trees are put under pressure and drop their needles to conserve water. He advised cutting an inch off the base and keeping the tree topped up with water daily.