Germany plans to legalise cannabis as of April after lengthy wrangling between the governing parties over the final details and health protections.

"The law can thus come into force on April 1," deputy parliamentary group leaders Dagmar Schmidt of the Social Democrats, Maria Klein-Schmeink of the Green Party and Konstantin Kuhle of the pro-business Free Democrats (FDP) said on Thursday evening after a last round of talks.

"The regulations are a real milestone for a modern drug policy that strengthens prevention and improves the protection of health, children and young people," they said.

In future, adults will be able to grow cannabis at home and possess small quantities.

As of July 1, clubs will be allowed for joint cultivation.

The law aims to push back on the black market and reduce drug-related crime, curb dealing of cut or toxic substances and to bring down the number of users, the health minister has said.

Formally, the law is set to be passed by the Bundestag in the week starting February 19.

It would then be passed to the Bundesrat on March 22, where it is not expected to meet hurdles.

As of April 1, the cannabis ban in place for more than 40 years is almost certain to be lifted.

The legislation was agreed in November but there were lengthy discussions within the coalition over protections for young people, with one MP voiced fears that "people would literally be smoking weed on every corner".

The law remains unchanged since, however, except that its effectiveness is to be reviewed in several stages.