A man caught growing cannabis in a sophisticated hydroponic set-up at Medowie will spend at least a year behind bars.

The 36-year-old man, Corey Letherbarrow, has been found guilty of cultivating and possessing 12 cannabis plants in an old caravan.

Police say the plants were not just healthy, they were thriving, with the bumper crop having an estimated street value of half a million dollars.

Letherbarrow was sentenced to 18 months gaol with a non-parole period of 12 months.

He was fined $500 in costs for interfering with or altering an electricity meter.