Be sure that a 3 foot area around the hydrant is clear of any debris or obstructions.
During winter conditions it is very important to make sure the hydrants near your home or place of business are clear and free of snow. Do not push snow from parking lots up over hydrants.
If you are concerned about how the hydrant looks on your property, you are more than welcome to beautify the space around it with flowers. But in doing so, be aware that the hydrant must be visible, accessible, and that the possibility of destruction of your plant life around the hydrant is very high in the event of an emergency.
Vehicles should not park within 15 feet of a fire hydrant.