Place the split peas, potatoes, carrots, onion, and garlic into the slow cooker.
Add the vegetable broth, thyme, bay leaf, salt, and pepper.
Stir everything together until the ingredients are evenly distributed.
Cover and cook on low for 7 to 8 hours or on high for 4 hours.
Check that the split peas have softened and the potatoes are tender.
Remove the bay leaf and stir the soup before serving.