In a very large bowl combine squash, potatoes, beets, turnips, carrots, onion, and garlic. Drizzle with olive oil and toss to coat. Sprinkle with salt and pepper. Place squash mixture in a 3-1/2- or 4-quart slow cooker.
Cover and cook on high-heat setting for 3 to 4 hours or until vegetables are tender when pierced with a fork. Sprinkle with parsley.