Greens drug law reform spokeswoman Chloe Swarbrick, whose own medicinal cannabis bill was voted down in January, said her party would like to see the Government's bill go live much sooner than mid-2020.
Swarbrick said she had been speaking to Clark and Reti to get all parties working together.
"We think that it's important to ensure that we are getting the best possible outcomes for patients here. It's unfortunate that politics has obviously got in the way," she said.
Hikurangi Cannabis was the first New Zealand company to get a licence from the Ministry of Health to cultivate medicinal cannabis plants.
Managing director Manu Caddie said his company had been pushing hard to have the regulations in place six months after the law passes.
"It's almost going to make it untenable to have a company by that stage because New Zealand will be so inundated, I expect, by overseas companies by then."
Caddie said it was taking so long to progress that some people who made submissions on the bill would no longer be around to see the legislation in place, let alone access the drug.
"That's a real tragedy and that's why we need that urgent action."
Paul Manning, a director of medicinal cannabis start-up Helius Therapeutics, said most people had been expecting a go-live date in mid-2019.
"We don't understand why it will take so long to go live.
"There's a commercial consideration of course, but the other factor is that we know that there are thousands of Kiwis out there who are suffering today because they can't access medicinal cannabis," Manning said.
The Government's medicinal cannabis bill goes further than any previous parliament has been prepared to. The introduction of a medicinal cannabis scheme will increase the availability of medicinal cannabis for pain relief and allow for the domestic manufacturing of quality medicinal products.
Health Minister David Clark said he expected the Health Ministry would continue to work "at pace".
"If we are to create a strong local industry, with the potential to export internationally, we must take the time to get the regulatory environment right. We need a regime that is both robust and flexible enough to respond to a developing industry.
Overseas experience suggests it can take several years to establish such an environment.
"In the interim, as a compassionate measure, the legislation introduces a legal defence for the terminally ill to use illicit cannabis. That will be available once the legislation is passed into law in coming months," Clark said in a statement.