To cure concrete, keep it moist and at a moderate temperature for at least 3 to 7 days after finishing — by misting and covering it with wet burlap, sealing the moisture in with plastic sheeting, or spraying on a curing compound. Curing is not the same as drying; it is keeping water in so the cement can keep hydrating and gaining strength.
Curing is the most under-rated step in a concrete job. Concrete that dries out in the first few days can lose a large share of its potential strength and end up with a dusty, scaling surface — and you cannot get that strength back later.
Why curing matters
Concrete hardens through hydration, a reaction between cement and water that continues for weeks. If the surface dries out, hydration stalls there and the concrete stays weaker and more porous. Proper curing can mean the difference between a slab that reaches full strength and one that gains only a fraction of it — most of the benefit comes from keeping it wet through the first 7 days.
Wet curing
The most effective method is to keep liquid water on the concrete: pond it, run a soaker hose, or lay wet burlap and keep it damp. Cover it so it does not dry between waterings. Start once the surface is firm enough not to mar, and keep it continuously moist — intermittent wetting and drying can actually promote cracking.
Sheet and compound curing
Plastic sheeting (6-mil poly) laid over the slab traps the concrete's own moisture — cheap and effective, though it can mottle the color. Liquid curing compounds spray on to form a membrane that holds water in, which is the common choice for driveways and larger pours where wet-covering is impractical. Either way, the goal is the same: stop the water from leaving.
How long to cure
Cure for a minimum of 3 days; 7 days is the practical target for most jobs, and longer in cold weather. Concrete keeps gaining strength for about 28 days, but the early curing window does the heavy lifting. For when you can actually use the slab, see the curing-time guide.
Common questions
Is curing just letting concrete dry?
No — it's the opposite. Curing keeps concrete moist so the cement can keep hydrating. Letting it dry out too soon leaves it weak and dusty.
How long should you cure concrete?
At least 3 days, ideally 7, and longer in cold weather. Most strength is gained in that early window, though full cure takes about 28 days.
How do you keep concrete wet for curing?
Mist and cover with wet burlap, lay plastic sheeting to trap moisture, or spray on a curing compound. Keep it continuously damp, not wet-then-dry.