Plain old white vinegar - I love the stuff! It is useful dozens of ways around the home to clean, disinfect...and today's use is to soften clothes.
Use about 1/2 cup of plain white vinegar in the washer - just the regular wash cycle. Works great, and is a more natural and frugal option for softer clothes with less static cling.
More healthy, frugal cleaning tips - and easy to make homemade cleaning formulas all at: