Thames Valley Police received a tip off the drugs were in woodland near Oxford on Saturday.
Officers left a notice which read: "Ooops! Sorry we missed each other, but feel free to call me on 101 so we can discuss a deal. Lots of love, TVP xx."
The force tweeted that they had left the note because "#WeveGotManners".
The drugs were discovered in woodland between Wolvercote Mill Stream and the A34 near Oxford.
Thames Valley Police said the drugs were "seized and destroyed". No-one has been arrested.
Police left a light-hearted note saying "sorry we missed you" after digging up a cannabis plantation.