Here's what you'll need to make yours:
4- 4oz. bars of grated Castile soap
1- 78 oz. box of Borax
8- 16 oz. boxes of baking soda
3 tsp. (15mL) lavender essential oil
Ebates.com you can get 4% cash back (and 8% if it's a Double Day). Woo!
We grated our soap using a plain ol' cheese grater, which was a big hit with the little man. He wanted to get in on the action (see below) which saved this Mama a ton of forearm effort.
You can also use a food processor to do this step, if you don't have free labor available in your house. :)
Once we had the soap all grated, we threw it in a large plastic pail and tossed in the other ingredients. I used my hands to mix it all up and voila! Homemade powder laundry detergent!
Each load only takes 2 tablespoons of detergent, so this one batch will cover 288 loads of laundry. All together, the ingredients cost me about $25, which equals about 9 cents per load. Talk about saving money!
UPDATE: I've had quite a few questions about this recipe so I'll update you with some of the FAQs --
1. As far as I know, this detergent is HE/front load washer safe. You may have to adjust the amount you use slightly, but it's up to you to figure out how much more/less you need to get the same scent power as the 2 tblsp. I use in my top load washer.
2. You can substitute the castile soap with Fels-Naptha. I've always seen Fels-Naptha in the laundry detergent section of my local Wal-Mart, so it ought to be easier to find than the castile soap. I'm not sure how Ivory soap or any other similar soap would work out - I'm afraid it might be a really "sudsy" outcome though.
3. You can use washing soda instead of baking soda, if you prefer. I don't see a need in doubling up on the cleaning power since I'm already using Borax (which is pretty awesome on its own) and the castile soap.
This post does contain an affiliate link to Ebates.com. If you sign up through it, it does not cost you a thing, and does give my account a small credit which helps me keep this site going. Thank you!
Update 4/13/16 -- I've turned off comments on this post since the majority that it gets nowadays are spam. If you have any questions that aren't answered already, you're welcome to email me at firstname.lastname@example.org. Thanks for stopping by!