Police have seized around 400 cannabis plants from a huge farm on the outskirts of Newquay.
The plants were located in a large poly tunnel - each was at least 6 feet tall.
Four people were arrested on suspicion of being concerned in the production of cannabis.
Inspector Dave Meredith said he hoped it would put more pressure on drug dealers:
This was a substantial cannabis cultivation and one on the largest cannabis grows the police have located in Cornwall for several years. This cannabis crop was due to be harvested in the next few weeks, and we are fortunate to have located it before it was harvested and moved elsewhere. Large scale cannabis grows such as this generate considerable revenue for criminals gangs and are often linked to organised crime groups.