Chances are good that you already have some earthworms in your garden. However, to do the most good, you want to attract lots of worms. Luckily, this is not terribly difficult, and is more about what you do not do than anything. The most important thing to remember is that worms like organic matter and moist soil. They dislike harsh pesticides, herbicides and chemicals. Keeping these two principles in mind will help you to garden with earthworms successfully.
Turn over your garden's soil. To do this, dig up the first 6 to 8 inches with your mattock, hoe, spade or other digging implement.
Amend the soil with compost. All soil types can benefit from the addition of more organic material. Earthworms enjoy it as well, and will find their way to it naturally.
Start a worm pile near your garden. Begin by layering some kitchen scraps with grass clippings, leaves and soil in an area near the garden. Continually add more organic matter, always ending it with a thin layer of soil. According to Mother Earth News, worms need soil to aid in digestion. Adding soil to the top of your worm pile will attract the worms to the new organic matter. They will then digest it and break it down for garden use.
Harvest the dirt from the worm pile once or twice a season. Do this by gathering dirt from the bottom center of the pile. This is the place where the worm castings (worm waste material) are likely to be the most decomposed. Do not harvest the worm castings very frequently. Worms require dark, moist environments and do not like direct sunlight or air.