How long do you leave baking soda on mattress?

It depends on how bad the mattress smells or how long it's been since it was cleaned. Mattresses collect dust, dust mites, and odors easily, so they need to be cleaned regularly. Baking soda is a really simple and effective cleaning agent for mattresses. Sprinkle enough baking soda over your mattress to cover it in an even layer. For minor odors, leave the baking soda to sit for at least half an hour. However, the longer you leave it, the more it absorbs moisture and odor-causing particles. In fact, you can leave it for a full 24 hours for the best results. Then, use an upholstery attachment or a handheld vacuum cleaner to vacuum up all of the baking soda, leaving your mattress clean and refreshed.