Two men have been sentenced to 12-and-a-half years in prison over their involvement in a large illegal cannabis-growing operation at Toolamba in northern Victoria.

The pair, Duy Duc Dao and Quoc Van Tran, were sentenced in the County Court after pleading guilty to cultivating a large commercial quantity of cannabis. They will each have to serve a minimum of eight years and four months before becoming eligible for parole.

The case relates to a police raid on a property near Shepparton in February 2022. Investigators discovered thousands of cannabis plants being cultivated inside large greenhouses on the rural property.

Authorities found 8,805 plants across two greenhouses. The plants were being grown using extensive equipment, including lighting and irrigation systems. Police also identified evidence that electricity and water meters at the property had been tampered with.

When the plants were seized, the total weight was approximately 5.1 tonnes. The court heard this represented the largest reported cannabis seizure by weight in Victoria.

The prosecution estimated that the crop could have been worth between $22 million and $26 million if the plants had reached maturity and been sold in bulk.

Dao and Tran were arrested alongside three other people following the police operation. Those three people later failed to appear after being released on bail and remain wanted, according to the court.

During sentencing, the judge considered the men's personal circumstances and their previous lack of criminal records. Both men had experienced financial difficulties and had supported relatives overseas.

The court heard that Dao had been unemployed and carrying significant debt at the time of the offending, while Tran had worked in several occupations before becoming involved in the agricultural operation.

The men told the court they had not initially understood that the work they had accepted involved illegal drug cultivation. However, the judge found that they continued participating after the nature of the operation became apparent.

The sentencing brings the court proceedings against the two men to an end, although other people allegedly connected to the operation remain at large.

The case demonstrates the scale of illegal commercial cannabis cultivation that authorities can encounter in regional farming areas. Large growing operations can involve significant infrastructure and substantial financial investment.

Police said the seized crop would have had a significant estimated value if it had reached maturity and entered the illegal market. Its destruction prevented the plants from being harvested and distributed.

The two men will remain in custody while serving their sentences. Their parole eligibility will depend on the minimum periods imposed by the court and the operation of Victorian sentencing laws.

The case remains separate from the proceedings involving the other alleged participants, who have not been brought before the court for final determination.