A father who grew a cannabis crop and planned to traffic the drugs to pay for his son's treatment for an ice addiction has been jailed for four years.

When Veli Selmani learned ice was behind his 26-year-old son's increasingly aggressive behaviour, he vowed to get help and paid $40,000 for his son to attend The Hader Clinic, a renowned rehabilitation centre.

Knowing the treatment would put further strain on his family's tight finances, Selmami also acted on the advice of a friend, who said growing and selling cannabis might be the best way to find extra cash.

It proved, the County Court heard on Wednesday, a disastrous decision and one the judge described as a "misguided" attempt to help.