This security door is the same type used to protect Germany's gold reserve. But at this facility, it's securing green gold. Here, they grow cannabis for medical use.

Right now, it's not psychoactive. If you would just eat the plant right now, you would not get high.

But a new law decriminalizing possession and home cultivation means they soon hope to expand their business.

Now we are allowed to grow more cannabis, which we can then also sell directly to the pharmacies. The second part, which is very important to the patients, is that cannabis now is declassified. It's not a narcic product anymore, which means that any doctor can now prescribe it.

From the first of April, adults will be allowed to possess up to 25 grams of the drug in public, hold 50 grams at home, and grow a maximum of three plants.

Here we show the whole plant. There's seeds in here because this is for seed production.

From July, private cannabis clubs can supply 500 members on a limited basis. Stefan is one of those who's been campaigning for legalization. A director of Berlin's Hemp Museum, he celebrates all things marijuana and sees the new law as a partial victory.

It's not the law we expected, but it's a good law because we will have 180,000 less prosecutions in the next year. There will be a big relief for cannabis consumers if you can have 25 grams of cannabis with you without being in fear of arrest, in fear of problems with the police.

But there are restrictions. For example, you have to be over 18 and can't smoke around areas, including playgrounds and sports centers. The potency will also be limited.

Getting this across the line has been quite the battle. The government claims it will help curb the black market and ensure a safe quality product. But opponents say it ignores the health issues and will overburden the police and justice system.

Polls show the public is also divided with a slim majority against it.

I think alcohol is the same dangerous as cannabis, and so I think it's okay. Now they can be sure it's good quality, and at least the state will get the taxes from that.

I think it's bad because of the youth.

It's dangerous. But this is now a growing industry. If this step is successful, in the future, cannabis could be sold in licensed shops. Siobhán Robbins, Skynews, Berlin.