How to Remove Mildew from Canvas Awnings
To remove mildew from a canvas awning, you can use your own cleaning solution made with bleach. First, brush off any dirt and debris from the awning with a broom. If possible, take your awning off of its frame and clean it on a flat surface to make the process easier. Once you've brushed everything off, hose the awning down until it's completely wet to make it easier for the cleaning solution to spread. Then, prepare your cleaning solution by mixing 1 cup bleach, 1/4 cup mild liquid soap, and a gallon of cool water in a bucket. Dip the awning into the mixture, covering every inch of the fabric, and give it 15 minutes to soak. After the cleaning solution has had time to soak, scrub the top of the fabric with a soft-bristled brush before rinsing it off with the hose. To dry your awning, either hang it on a clothesline or let it sit on its frame.
Gather your supplies. To clean mildew from a canvas awning, you'll need a cleaning solution made from water, bleach,or a mild liquid soap. Don't mix bleach with household cleaners, which may cause toxic fumes. To get the job done, you'll need some supplies and cleaning equipment, including: Ladder Broom Tarps or plastic covers Hose Large bucket Clean cloth or rag Soft-bristled brush Fabric protecting treatment spray Remove small awnings. Smaller awnings can be removed from their frames so that you can clean them on the ground level. Carefully remove the awing from the arms and frame. When you've got the awning down, lay it on a flat, clean surface to clean it. Set up a ladder for larger awnings. Awnings that are too large, too heavy, or too awkward are best left in place. You can clean them where they are, but you will need a ladder to access the top to clean the mildew. Look for a ladder with a platform at the top that will hold your cleaning supplies. If you have access to a cherry picker or other lift device, you can use those as well. Protect the surroundings. This is especially important if you're going to be cleaning the awning in place, because you don't want to splash cleaning solution onto nearby items. Cover the area under and around the awning with tarps or plastic sheets. Be particularly careful about covering things like plants, furniture, grass, decorations, carpets, and fabrics. Brush off dirt and organic debris. Before you start cleaning off the mildew, use a broom to clean off any dirt, leaves, sticks, twigs, cobwebs, or other organic materials that have accumulated on the awning. Leaving organic matter on your awning for an extended period can lead to damage, because the matter will cause deterioration to the fabric as it rots. Identify mildew on an awning. Awnings do require regular cleaning, but mildew demands a different kind of cleaning solution and more elbow grease. Mildew is a type of fungus that's similar to mold. On an awning, it will likely appear as gray or white spots, and will look like a powder. You can simply use a regular cleaner if your awning doesn't have mildew. Hose down the awning. To get the best results from your cleaning efforts, start by hosing down the awing so it's completely wet. This will make the cleaning solution easier to spread, and the mildew easier to remove. Mix your cleaning solution. To remove mildew from a canvas awning, you'll need a cleaning solution made with 1 cup (237 ml) bleach, ¼ cup (59 ml) of mild liquid soap, and 1 gallon (3.8 L) of cool water. If you need more cleaning solution, simply double or triple all the quantities. Mild liquid soaps include laundry soaps that are designed for sensitive skin, babies, or delicate fabrics. Do not use chlorine bleach on canvas, as this can damage the fabric. For colored awnings, use a color safe bleach. It's also a good idea to test a patch of the cleaning solution on an inconspicuous area to test for color fastness. Place some cleaning solution on a small patch of the top side of the awning and let it sit for 20 minutes before rinsing and checking for discoloration. Soak the awing in cleaning solution. Dip the clean cloth into the cleaning solution and spread the cleaner all over the awning. Re-dip the cloth as necessary so that cleaning solution reaches every inch of the fabric, otherwise you might miss some of the mildew. Once the entire surface of the awning has been soaked with cleaner, let it sit for about 15 minutes. This will give the cleaner time to soak into the fabric and kill the mildew. Scrub the canvas. When the cleaning solution has had time to soak in, take the soft-bristled brush and scrub the top side of the fabric. Use a vigorous circular motion to generate suds. Go over every inch of the awning to scrub away all the mildew. If the cleaning solution starts to dry anywhere, re-soak the area before you scrub. Rinse the awning. After scrubbing mildew from the whole awning, rinse it well with clean water from the hose. Continue rinsing until all the soap and dirt have been washed off. You don't want to leave any bleach residue on the fabric, or it could cause early deterioration. If there's any mildew left on the awning, repeat the soaking and scrubbing steps until it's gone. Allow the awning to air dry. Most awnings are designed to dry quickly after the rain, so it won't take your awning long to air dry. If you cleaned your awning in place, simply let it dry on the frame. If you removed your awning, hang it to dry on a line before reinstalling it. Never dry canvas awnings in a dryer, as they may shrink. Re-treat the awning. When you bought your awning, it would have been treated with a water- and stain-resistant coating to protect it from water and discoloration. But scrubbing it with bleach will have removed this coating, so you'll need to reapply it. Look for a commercial-grade fabric guard that can be sprayed on. Once the awning is dry, spray the fabric guard onto the top side of the awning. Read and follow the manufacturer's instructions for specific instructions. Some awning warranties will be voided if you use silicone sprays, so make sure you check the conditions of your warranty. Return the awning to its frame. For smaller awnings that you removed to clean, return the awning to its frame once it's dry and after the water-resistant treatment has had time to dry. Hose down the awning monthly. Keeping your awning mildew-free is much easier than having to clean mildew from it, but there are things you'll have to do monthly and yearly to prevent mildew from growing. Hosing down the awning regularly with clean water will remove dirt, organic matter, and other things that could lead to mildew growth. To hose down the awning, simply set up a ladder and use a garden hose to drench the awning. Pay special attention to remove any twigs, leaves, or other debris that's built up. Once you soak the awning, let it air dry. Clean it yearly. To clean your awning for annual maintenance, the process is the same as for removing mildew, but you don't use bleach in the cleaning solution. This will remove pollutants, organic matter, dirt, and other contaminants. Either remove the awning from its frame or set up a ladder to reach the top of the awning. Soak the awning with clean water. Mix a cleaning solution with 1 gallon (3.8 L) of water and ¼ cup (59 ml) of mild liquid soap. Soak the awning with the cleaning solution and let it sit for 15 minutes. Scrub the awning with a soft-bristled brush. Rinse and awning and allow it to air dry. Store it properly. When you remove your awning for winter or to store it for extended periods, you can prevent mildew when the awning is in storage. Perform your annual cleaning before storing the awning. Make sure the awning is clean and completely dry before putting it away. Store the awning somewhere clean and dry so that mildew isn't attracted to the area. Keep the awning somewhere well-ventilated, as this will prevent mildew from settling. 
Gather your supplies. Remove small awnings. Set up a ladder for larger awnings. Protect the surroundings. Brush off dirt and organic debris. Identify mildew on an awning. Hose down the awning. Mix your cleaning solution. Soak the awing in cleaning solution. Scrub the canvas. Rinse the awning. Allow the awning to air dry. Re-treat the awning. Return the awning to its frame. Hose down the awning monthly. Clean it yearly. Store it properly. 