Mayor Bloomberg said yesterday that he opposes legalizing marijuana — just a day after announcing the NYPD will give out desk appearance tickets to people found with small amounts of weed.

“It’s much more potent than when you and I were teenagers,” he said on his WOR radio show, without explaining how he knew that.

Legalizing pot, Bloomberg said, would encourage peddlers to sell more dangerous drugs.

He also weighed in on pot growers who oppose having electric meters in their apartments.

“They’re using their big sun lamps, and they’re growing marijuana. It would be obvious,” the mayor said.