Mold grows on a couch if the couch has become wet from moisture build-up. Couches placed in storage might become wet from humidity, and without proper ventilation, mould develops. Cleaning mould from a couch is not difficult, but you want to make sure you eradicate all mould spores before placing the couch back into your home.
Remove the couch from the home if possible and set outside on concrete or gravel. Place removable cushions on the concrete.
Put on rubber gloves and a painter's mask to avoid touching and breathing toxic mould.
Scrape or brush off mould from the couch and cushions. Use a soft bristled brush or nylon scrubbing pad to brush the mould. Rub gently against the fabric of the couch.
Vacuum the mould from the couch and cushions using a vacuum attachment. Go over the entire couch, making sure to get into deep pockets in the sides and back of the couch where the cushions have rested. After vacuuming the entire couch, remove the sweeper bag filled with the mould and dispose of it in an outside trash receptacle.
Mix one part water and one part rubbing alcohol, and wipe over the entire surface of the couch and cushions with a clean rag. The rubbing alcohol kills any leftover mould hiding in the fabric of the couch.
Leave the couch and cushions in the sun to dry out. The sun's rays help to kill any remaining mould in the fabric of the couch. If you cannot take the couch out in the sun, set a fan or electrical heater by the couch to dry it out.
Sprinkle baking soda over the couch and cushions, and allow it to remain for two to three hours; then vacuum up the baking soda. The baking soda neutralises any musty smells left from the mould.