To clean your canopy, simply use warm, soapy water. Dish detergent works well and will remove any heavy deposits. Remove the soap off both sides before setting the canopy up to dry. A garden hose with a spray nozzle set to a “flat” setting works well. Spray from top to bottom in vertical swipes until all of the soap residue has been removed. Do not use bleach - it will cause the fabric to discolor.
Fully stretch the canopy fabric out. To keep it off the ground, you can use a clothesline, sawhorses, or even the bed of a pickup truck. Many trucks will have a black spray in or fiberglass bed liner that retains heat, speeding the drying process. Allow air and light to hit as much of the fabric as possible — this will reduce the chance of mold and mildew.