CNBC's Jim Cramer warned on the eve of Canada's legalization of marijuana for recreational use that he'd stay away from pot stocks for the time being.

"Everything related to the Canadian cannabis space has already run up dramatically and I'm worried that many of these companies aren't even worth speculating on," he said Tuesday evening on "Mad Money."

In fact, Canadian cannabis stocks such as Canopy Growth and Tilray have been soaring. Canopy has gained more than 400 percent in the past 12 months. Tilray, whose volatile trading captivated Wall Street in September, has skyrocketed more than 800 percent since going public in July.

Canopy and Tilray opened sharply lower on Wall Street at Wednesday's open.

Cramer argued, "There could be a lot of disappointment once it turns out that legal marijuana is a lot less profitable than illegal marijuana."

Canopy Growth CEO Bruce Linton, speaking with CNBC's Deirdre Bosa from one of his stores in Newfoundland, disputed that notion.