Here’s the story
You can also read it in the Washington Post
Here’s parliament house’s home page – as yet nothing published about the act
The South African reports
The news was reported by the state-owned paper The Herald.
According to the paper, it was announced by Health and Child Care Minister Dr David Parirenyatwa in a Government Gazette on Friday under Statutory Instrument 62 of 2018 (Dangerous Drugs – Production of Cannabis for Medicinal and Scientific Use Regulations).
On Friday 27 April 2018 Zimbabwe became the second African country to legalize marijuana for medical and scientific purposes. 
In 2017, Macro-Economic Planning and Investment Promotion Minister Dr Obert Mpofu noted that a Canadian firm had applied to cultivate medical cannabis in Zimbabwe, stating the government was “seriously considering” the application.
Zimbabwe has legalized the production of marijuana for medicinal and scientific purposes, making it the rare African country to turn the drug into a source of revenue.
A government notice issued by the health minister says individuals and corporations can apply for licenses to grow marijuana, whose production and possession had brought up to 12 years in prison.
Recreational use remains illegal.
The decision is a marked shift from the traditionally tough stance on marijuana in the largely conservative country where members of Parliament who had advocated for legalization often were openly mocked.
The tiny nation of Lesotho last year became the first in Africa to issue a license for medical marijuana. Countries including Malawi and Ghana are reportedly exploring ways to legalize the drug.
A South African court last year ruled that private use of marijuana was legal but the government appealed the ruling at the Constitutional Court.
Much of Africa still criminalizes the production and use of marijuana.
Africa is second only to the Americas in terms of production and consumption of the drug, according to the United Nations’ 2017 World Drug Report.