The two countries disagree on the level of "dockage'' — foreign material such as weeds, other crops and detritus — that should be considered acceptable in Canada's canola exports to China.
The Chinese government had given Canada until Thursday to cut the level of foreign material in its deliveries by more than half.
Trudeau made the announcement about the extension in Beijing, where the canola dispute was expected to dominate the trade agenda during his high-level meetings and the G20, which gets underway later this week.
Riders and their horses pass through a canola field as they take an afternoon trail ride near Cremona, Alta., on July 19, 2016. The head of a national group that represents canola farmers says they're concerned that China's plan to impose stricter import regulations on the crop this week will put them at a competitive disadvantage and clog Canada's grain terminals. (Photo: Jeff McIntosh/Canadian Press)
"We're happy to reassure Canadian farmers that (at) the Sept. 1 deadline we will be able to continue with the current regime of canola and we (will) work together very closely towards a long-term solution in the coming days and weeks ahead,'' he said.
Chinese Premier Li Keqiang told reporters through a translator that both sides have "shown flexibility'' on the issue.
"Both sides will be able to make some mutual adjustments with the larger picture of China-Canadian trade and ties in mind."
He noted that while China itself is a large canola producer, it has no intention to keep its door closed to other exporters. But he said Chinese producers and consumers have concerns that disease could be imported.
"We believe that both sides will be able to make some mutual adjustments with the larger picture of China-Canadian trade and ties in mind,'' he said.
Issue of 'absolute importance'
International Trade Minister Chrystia Freeland, who is part of the delegation travelling with Trudeau, had earlier said the issue is of "absolute importance'' to the Canada-Chinese trade relationship.
"As everyone knows, this was something that was a very difficult issue for our canola growers, for our canola exporters and we were very, very pleased to be able to achieve today that Canadian canola shipments can continue,'' Freeland said.
China's ambassador to Canada, Luo Zhaohui, has stated that Canada has been inflexible and unfair in its approach to talks that began about seven years ago over Chinese concerns about rules for the make-up of canola shipments.
Luo said China buys 87 per cent of its canola from Canada because of its good quality and production. But he warned China can always look elsewhere for the product, if necessary.
Also on HuffPost