The Waitrose farmers will help the WildCare wildlife habitat scheme to complete its first official records of flowers.
Hot varieties include the bee orchid, the autumn lady's tresses orchid and the burnt orchid, which has flowers said to look like people in pink-spotted pyjamas.
WildCare works with farmers who have turned at least a tenth of their land over to wildlife habitats, said business services manager Tim Oliver.
The initiative is run by the company AB Agri in partnership with Waitrose Select milk farmers. Booklets will help farmers with any identification doubts.
"There are more than 50 species of wild orchid native to the British Isles," said Oliver. "Many are rare but are just never spotted.
"They are small and blend in so well with their surroundings. But orchids are some of the most iconic flowers of the British countryside and deserve to be preserved."
He said hitting the right balance between food production and helping wildlife was one of the main challenges of the WildCare scheme.