A Tasmanian coroner has found a teenager died from an overdose after researching on the internet how to extract opium from poppy heads.

The 17-year-old boy died last November after drinking a brew he made from poppies.

After researching how to extract the morphine, the teenager and a friend went to a farm at Lewisham, near Hobart, where they took five kilograms of poppy heads.

The pair made poppy tea which they drank with another friend.

The teenager continued drinking the liquid alone before going home to sleep. He was found dead the following day.

Coroner Chris Webster said the teenager died from morphine toxicity, after drinking the opium extract.

He said there were signs on the poppy farm fence prohibiting trespass.

The Coroner made no recommendations.