Plan to complete your project before the weather gets too cold. New concrete should stay at a temperature of 50 F or greater for at least a week. As the temperature drops and approaches freezing, hydration is adversely affected, which prevents the concrete from gaining strength.
Assess the drainage in your location to determine if a temporary water barricade is required. If so, use wood planks to surround your fence post bases to prevent running water from interfering with your concrete pour.
Dig holes deep enough to accommodate one-third of the length of the post. Widen the holes to three times the post's diameter. Ensure that the walls of the holes are stable and firm. Position each fence post and hold in place with a brace or the assistance of a helper. Line each hole with gravel.
Mix concrete according to package instructions. Pour some of the mix into each hole and combine with the gravel using a shovel. Pour additional concrete over top until the holes are filled.
Protect your newly poured concrete from excess surface water by covering it with plastic. While hydration is necessary for the curing process to take place, too much water on the top interferes with the mix ratio and softens the concrete surface. Initial setting occurs within two to three hours of concrete pouring and requires cover from steady rain to ensure maximum surface durability.
Ensure that your curing concrete stays hydrated. Moist-cured concrete is 50 percent stronger than concrete that is left to cure dry. As long as excess water is kept off freshly poured concrete, rainy weather actually contributes to moist curing because of the humidity that is present.