Entrepreneurs looking to cash in on California’s new marijuana gold rush flocked to Los Angeles this week for the city’s Fourth Annual Cannabis World Congress & Business Exposition, taking in advice and pitches from venture capitalists to a marijuana “sommelier”.

Workshops were conducted, business cards were swapped with more than 200 bustling booths – exhibiting everything from pot paper, to shampoo and even suppositories – at the LA Convention Centre. It was a spirited free-for-all that anticipated one thing: 1 January 2018 – a date that puts dollar signs in many a Californian’s eyes.

For it is then that the state will fully legalise recreational marijuana use, thanks to Proposition 64 – the adult use of marijuana act – which was passed last year. Explosive growth is then projected for the industry and the state; growth which may represent a boon to the tune of $7bn (£5bn), as well as the creation of hundreds of thousands of jobs.

“This is truly an exciting time,” gushed a speaker at one of the workshops, which covered the gamut of helpful weed topics, down to the burgeoning Canadian market and marijuana food pairings. “We hope you’ll enjoy the ride!”

Oils-free, biodegradeable plastics from hemp were touted as a potential “$400bn global market” in the “Hemp MBA In A Day” seminar – a number which would seem pie-in-the-sky for now at least.

Though the sky seemed the limit, the Expo’s takeaway messages were sometimes contradictory. Caution hung just under the surface of many of the big sells, with California's marijuana business still very much in flux while it prepares for the big day and a future that is difficult to predict.

In pictures: 4/20 Marijuana world rallies Show all 26 1 /26 In pictures: 4/20 Marijuana world rallies In pictures: 4/20 Marijuana world rallies A man wears a marijuana leaf mask during the annual 4/20 cannabis culture celebration at Sunset Beach in Vancouver, British Columbia AP In pictures: 4/20 Marijuana world rallies A lady smokes marijuana on Parliament Hill on 4/20 in Ottawa, Ontario Getty Images In pictures: 4/20 Marijuana world rallies James Reed smokes a joint during the Denver 420 Rally at Civic Center Park in Denver, Colorado Getty Images In pictures: 4/20 Marijuana world rallies People sign a 4/20 sign on Parliament Hill on in Ottawa, Ontario Getty Images In pictures: 4/20 Marijuana world rallies A woman smokes marijuana on Parliament Hill on 4/20 in Ottawa, Ontario. Polling released showed strong support in Canada for a government drive to legalise recreational use of marijuana, but many would like the proposed minimum age for consumption to be raised. Sixty-three percent of respondents told the Angus Reid Institute they support legalisation Getty Images In pictures: 4/20 Marijuana world rallies A man smokes marijuana during the annual 4/20 marijuana rally on Parliament Hill in Ottawa, Ontario, Canada Reuters In pictures: 4/20 Marijuana world rallies Demonstrators smoke marijuana during the '4/20 Santiago' rally in favour of legalisation in front of the La Moneda presidential palace in Santiago, as part of the Global Marijuana March which is being held in hundreds of cities worldwide Getty Images In pictures: 4/20 Marijuana world rallies People play with a mock marijuana joint during a 4/20 party to demand legalisation and to celebrate marijuana culture outside the Senate building in Mexico City, Mexico Reuters In pictures: 4/20 Marijuana world rallies Adam Eidinger, co-founder of DCMJ, hands out free marijuana joints to DC residents who worked on Capitol Hill as part of the 1st Annual Joint Session to mark '4/20' day and promote legalising marijuana on Capitol Hill in Washington, DC Getty Images In pictures: 4/20 Marijuana world rallies In pictures: 4/20 Marijuana world rallies Police arrest Rachel Ramone Donlan after she handed out free marijuana joints to DC residents who worked on Capitol Hill as part of the 1st Annual Joint Session to mark '4/20' day and promote legalising marijuana on Capitol Hill in Washington, DC AFP/Getty Images In pictures: 4/20 Marijuana world rallies Police arrest Rachel Ramone Donlan after she handed out free marijuana joints to DC residents who worked on Capitol Hill as part of the 1st Annual Joint Session to mark '4/20' day and promote legalising marijuana on Capitol Hill in Washington, DC Getty Images In pictures: 4/20 Marijuana world rallies Thousands of people gather to smoke marijuana during the '420 Santiago'rally in front of the La Moneda presidential palace in Santiago Getty Images In pictures: 4/20 Marijuana world rallies People attend the Denver 420 Rally at Civic Center Park in Denver, Colorado Getty Images In pictures: 4/20 Marijuana world rallies Kevin Barron and Lasean Moore of Raleigh, North Carolina, share a joint during the Denver 420 Rally at Civic Center Park in Denver, Colorado Getty Images In pictures: 4/20 Marijuana world rallies Nic Ruhl takes a pull on a giant hand rolled joint at precisely 4:20pm MDT during the Denver 420 Rally at Civic Center Park in Denver, Colorado Getty Images In pictures: 4/20 Marijuana world rallies Various cannabis paraphernalia on display at a vendor's stall during the Denver 420 Rally at Civic Center Park in Denver, Colorado Getty Images In pictures: 4/20 Marijuana world rallies Mo Banez, of Austin, Texas, lights a joint during the Denver 420 Rally at Civic Center Park in Denver, Colorado Getty Images In pictures: 4/20 Marijuana world rallies A man displays a large container of cannabis during the Denver 420 Rally at Civic Center Park in Denver, Colorado. The rally, held annually, is a celebration of both the legalisation of cannabis and cannabis culture. Colorado is one of twenty-six U.S. states along with the District of Columbia that has legalised the use of cannabis either recreationally or medically AFP/Getty Images In pictures: 4/20 Marijuana world rallies Sitting in small groups on mats shaded by trees in the Rose Garden just across from the Knesset, participants lit up as the clock struck 4:20 for the local version of the traditional worldwide April 20 pro-marijuana events, known as '420' rallies Getty Images In pictures: 4/20 Marijuana world rallies An Israeli smokes a marijuana joint in Jerusalem during a rally at the Rose garden Getty Images In pictures: 4/20 Marijuana world rallies Sitting in small groups on mats shaded by trees in the Rose Garden just across from the Knesset, participants lit up as the clock struck 4:20 for the local version of the traditional worldwide April 20 pro-marijuana events, known as '420' rallies Getty Images In pictures: 4/20 Marijuana world rallies An Israeli girl poses with a mock marijuana joint in Jerusalem during a rally at the Rose garden, to celebrate 420 and to express their defiance of current laws Getty Images In pictures: 4/20 Marijuana world rallies aelis pass around a marijuana joint in Jerusalem during a rally at the Rose garden, to celebrate 420 and to express their defiance of current laws Getty Images In pictures: 4/20 Marijuana world rallies An Israeli smokes a marijuana joint in Jerusalem during a rally at the Rose garden, to celebrate 420 and to express their defiance of current law Getty Images In pictures: 4/20 Marijuana world rallies An Israeli smokes a marijuana joint in Jerusalem on April 20, 2017 during a rally opposite the Knesset to celebrate 420 and express defiance of current laws AFP/Getty Images

At the “How To Buy Equity In A Cannabis Business: What To Look For, What To Avoid” workshop, a how-to for both pot newbies and more experienced investors, another speaker warned “The industry has a lot of smoke and mirrors,” but only after suggesting that certain investment returns could go as high as 150 per cent.

Workshop leaders also gingerly tip-toed around the “Sessions Depression,” an industry term affectionately coined for the Trump Administration’s Attorney General Jeff Sessions, who is said to be considering a crackdown on America’s supply of cannabis. But many remained confident that California, the largest of the weed states, would lead a development juggernaut that would eventually be too hard for Congressional leaders to ignore, let alone put down (notably, a national bill known as the Marijuana Effective Drug Study Act of 2017, or MEDS Act, was introduced by conservative firebrand, Utah Senator Orrin Hatch on Wednesday).

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In room 501AB, Max Montrose, President of Denver’s Trichome Institute, which offers cannabis certification and education, led his “Interpening: The Art of the Cannabis Sommelier” workshop. A gawky 30-something with red hair and glasses, Mr Montrose explained to attentive business minds, millennials and retirees alike how he developed his discriminating palate in Colorado, the first state in the US to legalise medicinal marijuana, in 2012. “I was a kid on a cocktail of pharmaceuticals. At 13, I started noticing how different types of cannabis strains affected me,” said the self-described “weed nerd,” and creator of the Island Diesel Skunk sativa strain.

Grasping, as many other speakers did, to convince his new students of his expertise in such a young, unsettled industry, he added, meekly: “I mean, started teaching people before I had facial hair”.

Thousands attended the the Cannabis World Congress in LA (Lucy Nicholson/Reuters)

Mr Montrose then adeptly pointed out a huge gap in the classification of marijuana types, one which could potentially create a giant headache in a national weed rollout. “I've bought six different types of ‘blue dream’ at four different dispensaries. Many experts don't know much about the actual plants, they don't know what they're talking about,” he said, advocating strongly for marijuana DNA testing – to ensure customers know the strength of what they are buying.

Much else has yet to be ironed out in this industry; the state, its counties and cities are rushing to finish cobbling together a myriad of new regulatory laws, which will do everything from resolving taxation and licensing issues, to deciding whether a pot smoker can have their weed delivered by drone (the final verdict: no, as airspace is regulated by federal laws).

The patchwork of state laws was ticked off at hyper-speed in the popular “Open A Cannabis Business” workshop, led by Nicole West, an instructor at Clover Leaf University, a Denver-based training institute.

Ms West lovingly painted a picture of one of the state’s most successful growers who had “15,000 square feet and 197 air conditioners.”

But caution was still a watchword. “California is a big state,” she said. “But this isn’t like opening up a brewery – I’m sorry to be so negative”

She added: “Nobody that understands how to be commercial understands anything about weed, and nobody that knows about weed understands commercial – 25 per cent of operators will roll out strong, and everyone else is going to have to pick up the pieces”.

But despite the odd products, the high talk and the pearls of wisdom, the resolution of one important matter still remained to be addressed for this marketplace - that of inclusion.

It is a matter that is raising hackles within California’s minority communities, who want fair representation.

One Expo attendee Joe Cain, a Malibu Gold, laid out the problem.

“I’m part of a team of growers, but the opportunity is not always there,” he said. “Certain communities are less informed.”

“Right now,” he added, “my auntie, who's on a community board in Compton, is currently going to war with the city, trying to get equal opportunities for blacks to own dispensaries.”

Mr Cain said that many African-Americans are “being blackballed from entering the industry” due to prior marijuana convictions. It is an irony that is particularly ripe, given that the state’s coffers are due to fill up from weed sales.

Reverend Al Sharpton, the civil rights leader, weighed in on the issue as he gave the Cannabis Expo keynote speech, while newly appointed City of LA cannabis czar, Cat Packer, promised to level the playing field by creating a social equity programme for dispensaries.

It is clear that interest is high however with Expo attendance far in excess of last year’s 4,000 attendees. Ms West was enthusiastic “Colorado made $900m. Imagine what California’s going to do!”