Why a blanket goes on in the first place
Fresh concrete needs to stay above freezing while it cures, because a hard freeze on green concrete can wreck the surface for good and there is no sanding it back out. A curing blanket is an insulated cover laid over the slab right after finishing to hold the heat the concrete generates as it cures, so the cold air above it does not pull that heat away faster than the reaction can replace it.
The blanket is not decoration and it is not optional once the forecast calls for a hard freeze. It goes down the same day as the pour, while the slab is still warm from finishing.
How long it actually stays down
Two to four days covers most winter pours in this area, long enough for the slab to build the early strength that lets it handle a freeze on its own. A stretch of nights well below freezing, or a slab that went down late in the day with less daylight left to cure, can push that closer to a week.
Some winter mixes add an accelerator to speed up that early strength gain, which can shorten how long the blanket needs to stay down. It does not replace the blanket when a hard freeze is still forecast, it just gets the slab to the point where the blanket can come off sooner.
There is no fixed calendar date for this. The blanket comes off when the concrete has earned it, not when a certain number of days has passed, so we watch the forecast and the slab together rather than counting to a number and pulling it regardless.
What tells us it is ready to come off
We are reading the same signs a warm-weather cure gives off, just stretched out by the cold. The surface firms up, the color evens out, and the forecast clears of the hard overnight freezes that made the blanket necessary in the first place. Pull it too early into another cold snap and you are right back where you started.
Peeking under a corner to check does not hurt anything, but leaving the blanket off overnight because it looked fine at noon is how a slab that was almost through curing takes freeze damage on the last cold night instead of the first one.
Once the blanket is off
The slab still has weeks of curing ahead of it. A winter pour reaches the same milestones a summer one does, walking, driving, full strength, it just takes longer to get there because cold slows the chemical reaction doing the work. Treat a freshly uncovered winter slab as gently as a slab poured yesterday, even if the calendar says it has been down for a week.
The ground under the slab keeps dealing with frost heave every winter regardless of what happened during curing, swelling and shifting a little as it freezes and thaws. That is a separate concern from the blanket and one more reason a new slab gets watched closely through its first winter.
De-icing salt stays out of the picture through that first winter regardless of when the blanket came off. Salt pulls water into and out of the surface faster than a normal freeze and thaw cycle, and concrete that has not finished curing feels that harder than an older slab does.