...and works at temperatures above 12 degrees F, but it's tough on shrubs and grass and can eat away at concrete. Two other salts, magnesium chloride and calcium chloride, cost more but are less harsh (though still not great for plants) and work at much lower temps than rock salt (from 20 to 25 degrees below zero F). Still pricier is a nonsalt option called urea. It's usually used as a fertilizer, and it can be a little tough to find. Wear gloves when spreading any deicer by hand. For large areas, use a handheld spreader or a push spreader, but not a grass spreader (the deicing granules will gunk up its gears). Store deicers off the floor or in a sealed bucket to keep them dry.