Shred the soap bar using the fine grate of the box grater.
Next, add the shredded soap, washing soda, and baking soda to a large mixing bowl, and stir the ingredients well.
Finally, stir in the lavender essential oil.
Transfer powder laundry soap to a 1-quart mason jar for storage.
Notes
Use 2 tablespoons of the powder laundry detergent per load.I’ve included step-by-step images in the post above for visual guidance. If you would rather watch, I’ve included the complete step-by-step video tutorial here in the recipe card.