You open the bag in late autumn, ready to deal with the first icy driveway, and find a solid lump you’d need a hammer to break. Annoying, and mostly avoidable.
Salt attracts moisture. That’s the heart of the problem. Here’s how to store it so it stays usable.
Keep it off the ground. Concrete floors can hold dampness that creeps up into the bag. Stack bags on a pallet or a sturdy shelf, even a few boards, so air can move underneath.
Pick a dry spot. A garage or shed with a leaky roof, or a basement that gets damp, is the enemy. Look for somewhere that stays dry through humid summers and wet springs.
Check the bag, not just the room. A torn or poorly sealed bag lets in humidity, so look for small holes before storing. Plastic film that’s thick enough to resist punctures and closes properly makes a real difference. If you buy in large quantities, pay attention to how the bags are made and sealed.
Don’t stack too high. Weight at the bottom of a tall stack squeezes salt into a solid mass. Keep stacks modest and rotate them now and then.
Use the older stock first. Mark the date on the bag if you can, and use the oldest ones before opening new ones. Salt doesn’t spoil, but long storage gives moisture more time to cause trouble.
Once it’s open, reseal it. If you only use part of a bag, fold the top over and seal it tightly, or move the salt to a lidded bin. Leaving it open overnight in a humid space is enough to start clumping.
Handle clumps carefully. If a bag does harden, break it up gently before opening, rather than hacking at it. Wear gloves, since salt dries out skin. Don’t pour it near plants or metal you care about, because it can damage both.
Keep it away from kids and pets. Store it somewhere they can’t reach, and label it so nobody confuses it with something else.
If you’re sourcing salt in volume for a business or a municipal job, the packaging matters as much as the product. You can look at polyethylene packaging made for salt to get a sense of what suits that kind of load.
A bit of care in autumn saves a lot of swearing in January.