Flagpoles more than 10 feet high must be installed correctly, or you run the risk of the pole coming down and injuring a person or property. On windy days, poles not buried deep enough or secured correctly underground pose a safety hazard. Before you put up a 35-foot flagpole, learn how to properly install the base for a tall flagpole so it stays up and displays the flag correctly.
Locate a safe place to put up the flagpole. Avoid overhead wires, trees and buildings. Call your local utility companies or diggers hotline and ask them to mark any underground pipes or cables in the area you want to plant the flagpole.
Dig out a 30-inch-round circle of grass. Dig a 4-foot-deep hole in the circle. The hole must be wide enough for the sleeve around the bottom of the pole--30 inches wide. Remove any rocks that are in the way. When installing the sleeve, you will leave 2 inches of the sleeve above ground, so adjust the depth of the hole for this.
Place the flagpole sleeve in the hole. Mix the concrete in the wheelbarrow with the hoe. When the concrete is ready, start shoveling it into the hole. When you reach ground level, work the concrete to remove any air bubbles.
Place the garden edging around the edge of the hole. It should fit the 30-inch diameter hole you made in the grass. Use the duct tape to hold the garden edging in a circle around the hole.
Continue filing the hole until the concrete reaches the top of the garden edging. Move the sleeve around in the concrete to center it inside the garden edging. The concrete should stop 1/2 inch below the top of the sleeve.
Smooth the concrete so you have the desired finish. Allow it to dry for one to two days.
Remove the garden edging and place the 35-foot flagpole in the sleeve.