I recently made my first foray into homemade laundry detergent. I wanted to attempt the version that was easiest to store and required the least amount of work to make, so I grated two bars of Ivory soap, and mixed it with one cup of Borax and one cup of washing soda (also known as soda ash). I was less than ecstatic with the results--while it works fine in hot water, clothing washed in cold water tends to come out of the machine with little flakes of ivory soap all over it. I have taken to using it only for whites, linens, and dark towels, and pajamas, and using purchased detergent for our clothing. Considering that I do an average of 18 loads of laundry a week, using this homemade detergent on 2/3 of them still saves us a significant amount of money (It works out to about a nickel a load, versus about $0.15 a load for Purex or about $0.22 per load for Tide). However, I will be trying a new recipe next week, substituting oxygen laundry booster for the ivory soap. In the mean time, I put two tablespoons of detergent directly into the machine before the laundry for my whites, and I put two tablespoons into a mason jar with a cup of hot water to use with dark towels/pajamas. Since homemade laundry detergent does not have added rinse agents, I also add vinegar to the rinse cycle to help rinse the soap out. I put my vinegar into a downy ball and drop it in at the beginning of the wash.
Here are a few sites with laundry detergent recipes if you'd like to try it yourself:
Ten Homemade Laundry Soap Recipes
Make Your Own Laundry Soap
The Simple Dollar: How to make your own laundry detergent and The detailed visual guide
Suite 101: Making your own laundry detergent
If making your own laundry detergent isn't for you, you can still save money in the laundry room. Check out Frugal in the Laundry Room for more.