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Before getting started, you’ll want to make sure your patio is completely clear. Find a place away from your work area to stash patio furniture, dining sets, planters, grills, toys and anything else that may be damaged by free-flowing water or cleaning solutions. Your work area should ideally be as empty as you can get it.  Bring lightweight furniture inside, and move heavier pieces to the yard, sidewalk or a covered porch. Prolonged exposure to moisture can cause metal furniture and appliances to rust. Use a broom to dislodge as much loose debris from the patio as you can. This will make it easier to reach the more stubborn stains underneath, as well as give you an idea how extensive the cleaning methods you employ will need to be. Substances like compact dirt, dried mulch or sidewalk chalk may need to be scrubbed by hand using an abrasive sponge. Once you’ve swept the concrete, hose it down with a heavy stream of water. Push the dirt off to an adjoining section of the yard to drain. The concrete will then need time to dry before you can move on to other, more involved methods.  If it’s been awhile since you last cleaned your patio, add some mild liquid dish detergent to a bucket of warm water to make a soapy rinse. The surfactants in the soap will help break up dirt and oil more effectively.  In some cases, a good hosing may be all you need to remove a thin layer of dirt and sediment.

Summary:
Remove all furniture and other objects. Sweep away excess dirt. Spray the patio with a garden hose.