There are fears some arable farmers in Canterbury will now have missed the autumn planting window.
The Foundation for Arable Research said growers with heavier soil types had been particularly hard hit by wet weather and their planting plans may have to change.
Its research manager Rob Craigie said the soil was still so wet in parts of Canterbury growers may not be able to sow until August.
"The concern for cropping farmers is that we have been bringing our sowing dates earlier to get a higher yield potential. So if the planting's delayed from autumn into spring it's that yield potential that's lost and can't be made up," he said.
"So that's one of the major problems. Another one is if the farm's a dry-land farm, you lose that buffer of planting in autumn, when you have more soil moisture for the crop and if you're planting in spring during grain-fill, that moisture quite often runs out in January. It's a kind of double whammy there: less yield potential and more soil moisture risk."