You would have to be completely stoned if you have not noticed the proliferation of retail cannabis outlets -- usually in the guise of 'clubs' in the face of legal uncertainty -- that have sprung up in South Africa in recent years, including in the ubiquitous malls.

It has become an annual ritual at the typically staid Sandton Convention Centre: the pungent aroma of pot drifting into the cool autumn air over Alice Lane as a DJ cranks tunes and occasionally flings joints to an appreciative crowd.

The stoners outside may be chilled, but inside the Cannabis Expo one gets a whiff of the serious business of pot in South Africa and the wider region. The cannabis sector is budding and reaching new highs.

This year's expo was visibly larger than last year's and featured companies providing software and hardware solutions geared for the cannabis retail sector, businesses offering growing technology such as lights and nutrients, as well as the usual assortment of hawkers selling bud, edibles and paraphernalia.

It also had consultants from as far away as Zambia, and you know a sector is taking off when consultants start getting involved.

"In Zambia, we are looking at a multibillion-dollar business. We are officially starting growing, with all of the regulations approved, and licences will be issued from August for production and commercial use for medical marijuana and hemp," said Stephano Majawa, a director of the Lusaka-based cannabis consultancy Prosper Sievu Investments.

"There are 100,000 hectares...