Ottawa is acknowledging for the first time that legal recreational marijuana will not be for sale until August or September.

The federal government initially promised to legalize cannabis before July 1, before giving itself until the end of July. Bill C-45 makes it clear that cannabis will become legal at a date set by cabinet, not when the legislation passes.

However, it became clear two weeks ago that even the revised target would be hard to meet. Speaking to the Senate then, Health Minister Ginette Petitpas Taylor said provinces and producers will need two to three months to get ready for legalization after Parliament officially approves Bill C-45, making it likely at that point that legal pot would not arrive until late summer.

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Earlier this week, the Liberal government's representative in the Senate, Peter Harder, threatened to cut off debate to ensure the passage of legislation in May. This would have been the only way for legalization to occur in July.

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However, Mr. Harder's motion was opposed by independent and Conservative senators. Under a deal that was negotiated by Mr. Harder, the Senate will hold its final vote on Bill C-45 by June 7.

"The provinces and the territories have made it very clear to us that they will need eight to 12 weeks for implementation. Therefore, if you do the math, you can see that it certainly won't be July, 2018," Ms. Petitpas Taylor told reporters on Thursday.

She added that legalization was "a process, not a date."

"We will make sure we have a very appropriate roll-out of this process, we want to get this done right," she said. "There is no exact date [for legalization] that I can tell you."

In a statement, Mr. Harder said there is no need at this point to impose time allocation in the Senate to speed up the approval of the legislation. He said the new timeline offers greater clarity to all Canadians with an interest in the legalization debate, as well as time for in-depth scrutiny of the legislation.

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"This should give stakeholders, governments, businesses, law-enforcement agencies and other Canadians a timeline for how and when the bill will be ultimately dealt with by the Upper Chamber," Mr. Harder said.

The Conservative Leader in the Senate, Larry Smith, said the new calendar will allow for "critical analysis" of the legislation and its widespread impacts on Canadian society. Among other things, he wants to ensure the government conducts a wide-ranging public awareness campaign on the dangers of cannabis before legalization comes into force.

"Our objective was always to have an opportunity to have the proper amount of time to do the in-depth evaluation and represent the voice of Canadians who have serious questions about the legislation," Mr. Smith said in an interview.

If the Senate votes to amend Bill C-45 in June, the proposed legislation will return to the House of Commons where MPs will have their say on the amendments. If the MPs reject some or all of the Senate's amendments, the bill will have to go back to the Senate for approval.

To this point, senators have raised concerns about a potential increase in drug-impaired driving after legalization, the availability of the drug to young Canadians under the new regime, and the controls that will be in place on advertising and marketing of cannabis.

Bill C-45 is currently at the second-reading stage of the legislative process in the Senate, with a number of senators still wanting to speak on the principle of legalization.

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Starting in March, Bill C-45 will be studied by five Senate committees: social affairs, legal affairs, aboriginal peoples, foreign affairs and national security. The work of all committees is expected to be completed by May 29.

The Senate is currently composed of 41 members of the independent Senate group, 33 Conservatives, 12 members of the independent Liberal caucus and five non-affiliated senators. The Conservatives have been the most vocal opponents of legalization.

On Thursday, Prime Minister Justin Trudeau announced the appointment of two new senators from Ontario: educator Martha Deacon and former civil servant Robert Black.