Mold can be a huge problem for tents. It can be caused when a damp or wet tent is put away in a cool or dark place. Unfortunately, mould can cause health concerns for children and people with respiratory disorders. While prevention is the best remedy--being sure your tent is fully dry before storing it--if you have mould on your tent you need to clean it off. Bleach is one of the few products shown to effectively kill mould, but not everyone wants to use this chemical. Fortunately, there are alternatives.
Take the mouldy tent and your supplies outside to an open, sunny patch of grass. Fill the bucket about one-third full with water and add about 1 cup of lemon juice. Using a rag, scrub the mouldy areas of the tent. Also try using the scrub brush to really work the lemon juice mixture into the tent fabric. After five minutes of scrubbing, hose off the tent to remove the lemon juice. Let the tent air dry in the sun. If the lemon juice did not remove the mould, try the next step.
Take one cup of vinegar and put it in a spray bottle. Spray the vinegar on the mould and let it sink in for five minutes. Spray again and let sit for another five minutes. Wash with clean water and let dry in the sun. Again, if this method does not eliminate the mould to your satisfaction, try the next step.
Spray window cleaner onto the affected areas of the dry tent. Window cleaner contains ammonia which can help kill mould, but it is a chemical and some would rather use the natural solutions listed above. Scrub the window cleaner into the tent for about five minutes. Let it sit if you desire. Then hose off the tent and let dry in the sun. This should remove the last traces of mould.
Be sure to do this project on a sunny, warm day when you can fully dry the tent outside.