Put the potatoes into a large pot and cover them with water. Bring them to a boil and continue to boil for 10 minutes or until they are tender.
Put the eggs into a medium pot and cover with water. Bring the water to a boil, then remove it from the heat, cover it, and let sit for 10 minutes.
When the potatoes and eggs have cooled, chop them, and also dice the celery stalk.
Put the chopped potatoes and eggs into a large bowl. Add the celery, mayonnaise, relish, mustard, celery seed, garlic granules, salt, and pepper. Mix well to combine the ingredients. Place into the fridge for 30 minutes to chill before serving.