Chop the celery, potatoes, turnip and onion into ~1/2 inch pieces, as close to equally sized as possible so they’ll cook evenly.
Line 6 quart slow cooker* with plastic liner, if desired. Place chopped vegetables, garlic and spices into slow cooker.
Pour in the stock and stir the ingredients.
Cook on low for about 6 hours or until vegetables are no longer al-dente.
Turn off slow cooker. Using an immersion blender, blend for 3-5 minutes until well blended and no longer chunky. If you don’t have an immersion blender, you can transfer the cooked vegetables and liquid to a high-speed blender and blend in batches. Make sure soup has slightly cooled so you don’t burn yourself when transferring the soup or blending.
Ladle soup in serving bowls and add toppings if desired. I highly recommend mixing in about 2-3 tsp of plain unsweetened coconut milk yogurt for a slightly creamier soup that is still dairy-free!