When the temperature drops way below freezing, your local ACO Hardware Store has the best selection of Ice Melting products. In these temperatures,plain rock salt won't be an effective ice melter.
It stops working at about 20°.
 
Try Super RID ICE® potassium chloride. It works down to 12°.
It's also easier on the grass, concrete and decks around your house.
 
When it's really cold, ask for ICE Warrior® calcium chloride. It still works at -20° 

An easy way of distributing the ice melt product is the Scotts® Handy Green II spreader featured on the ACO Website.

Check out the Scotts® Spreader page for more details - Click Here