Question

when should you put rock salt down, before or during a snow storm?

Answer 1

Short answer: both can be useful, but the best approach depends on the storm and the temperature.

Practical guidance
- Anti-ice (pre-treat) before the storm if:
- Temperatures are above about 15–20°F (−9 to −7°C) and you expect light to moderate snow or freezing rain.
- You can apply a light, even layer (or better, a salt brine) to bare pavement. That helps prevent snow/ice from bonding to the surface and makes later removal much easier.

- De-ice (apply during/after) when:
- Heavy snow is expected — plow or shovel large accumulations first, then apply salt to the cleared surface so the salt contacts pavement and melts residual ice.
- Pavement is already covered with a lot of snow or compacted ice — rock salt under a thick covering won’t reach the pavement and will be slow to act.

Temperature limits and alternatives
- Rock salt (sodium chloride) is effective down to roughly 15–20°F. Below that its melting power drops off. For very cold conditions use calcium chloride or magnesium chloride (work at lower temperatures).
- Using a liquid brine pre-treatment is often more effective than broadcasting dry rock salt before a storm because it sticks to pavement and begins working immediately.

Other tips
- Shovel first when possible, then salt the bare pavement — salt works fastest when it can contact the surface.
- Use only the recommended amount (a light, even layer). Over‑salting wastes material and harms plants/pets and concrete/metal.
- If you need traction but not melting, use sand or an abrasive rather than extra salt.
- Keep pets’ paws rinsed/cleaned after walking on treated surfaces.

If you tell me the expected temperature and storm type (light snow vs. heavy, freezing rain, etc.), I can give a specific recommendation for your situation.