Slow Cooker Vegetable Soup

Name: Slow Cooker Vegetable Soup
Prep time: 15 min
Cook time: 240 min
Total time: 255 min
Ingredients: 1 tablespoon extra-virgin olive oil; 1 large sweet onion (finely diced); 4 garlic cloves (minced); 2 tablespoons tomato paste; 3 cups chopped green cabbage; 3 medium carrots (diced); 2 celery stalks (diced); 3 medium Yukon Gold potatoes (cut into ½-inch cubes); 1 large parsnip (peeled and diced); 1 bell pepper (diced); 14.5 ounces diced tomatoes (one can, with their juices); 8 cups low-sodium vegetable broth; 1 teaspoon dried thyme; 1 teaspoon dried oregano; 1 bay leaf; ½ teaspoon smoked paprika; ½ teaspoon fine sea salt (plus more to taste); ½ teaspoon freshly ground black pepper; 1 Parmesan rind (optional); 1 medium zucchini (cut into ½-inch pieces); 1 cup frozen green peas (thawed); 1 cup frozen sweet corn (thawed); 2 tablespoons fresh lemon juice

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This Slow Cooker Vegetable Soup is packed with veggies, potatoes, cabbage, and a flavorful tomato broth. It’s an easy soup that cooks in the crockpot with very little hands-on time. Perfect for a cozy dinner, meal prep, or using up extra vegetables in the fridge.

a round white bowl filled with vegetable soup with a spoon in the bowl.

I love making a big pot of vegetable soup, especially when the weather gets colder. It’s one of those recipes where you can toss in a little bit of everything, and it turns into such a comforting meal. I like adding potatoes to make it more filling, along with a squeeze of fresh lemon juice at the end to brighten up all the flavors. Plus, the leftovers are just as good the next day!

Recipe Overview

Skill Level

Beginner

Prep Time

15 mins

Cook Time

4 hrs

Ingredients You’ll Need

Below are the ingredients needed to make this slow cooker soup. Full measurements are listed further down on the recipe card.

ingredients for slow cooker vegetable soup.

Olive oil: Just a little for sautéing the onion and garlic.
Onion and garlic: Give a flavorful base to the soup.
Tomato paste and diced tomatoes: Add richness and a little acidity to the broth.
Vegetables: Cabbage, carrots, celery, parsnip, bell pepper, zucchini, peas, and corn make this soup hearty and colorful.
Potatoes: I like Yukon Gold potatoes because they hold their shape well and become nice and tender.
Vegetable broth: Use low-sodium broth so you can adjust the salt to taste.
Seasonings: Thyme, oregano, smoked paprika, bay leaf, salt, and pepper add plenty of flavor without making the soup complicated.
Parmesan rind: Optional, but it adds a delicious savory flavor as the soup cooks.
Lemon juice: Stirred in at the end for a fresh, bright finish. This can be optional. My kids don’t prefer it.

Tips for the Best Vegetable Soup

Don’t skip sautéing the onion and garlic. It takes only a few minutes and gives the soup better flavor than adding everything raw.
Cut the vegetables evenly. Keep the potatoes and other root vegetables around the same size so they cook at a similar rate.
Add the zucchini, peas, and corn toward the end. These vegetables cook much faster and can get too soft if you add them at the beginning.
Use whatever vegetables you have. Green beans, sweet potatoes, or butternut squash are great additions. Just keep in mind that firmer vegetables need more cooking time.
Adjust the broth. If you prefer a thicker, chunkier soup, start with a little less broth. You can always add more later.

How To Make Slow Cooker Vegetable Soup

Sauté the vegetables: Heat the olive oil in a skillet over medium heat. Add the onion and cook for 4-5 minutes, until softened. Stir in the garlic and tomato paste and cook for another minute, until fragrant.

Add the cabbage: Stir in the chopped cabbage and cook until wilted and reduced in size. Transfer everything to a 6-quart slow cooker.

Process shot to sauté aromatics, and add them to the slow cooker with the veggies.

Combine the ingredients: Add the carrots, celery, potatoes, parsnip, bell pepper, diced tomatoes, vegetable broth, seasonings, and Parmesan rind (if using). Stir to combine.

Slow cook: Cover and cook on LOW for 6-7 hours or HIGH for 3-4 hours, until the potatoes and root vegetables are almost tender.

process shot of adding the tomatoes and broth over the veggies in the slow cooker.

Add the remaining vegetables: Stir in the zucchini, peas, and corn during the last 30 minutes of cooking. Continue cooking on HIGH for 20-30 minutes, or on LOW for 45-60 minutes, until the vegetables are tender.

Finish and serve: Remove the bay leaf and Parmesan rind. Stir in the fresh parsley, basil, and lemon juice. Taste and adjust the seasonings as needed.

process shot of cooking the soup in the slow cooker and serving in a bowl.

Easy Variations

This soup is easy to customize depending on what you have available.

Add beans: Stir in a can of drained and rinsed white beans or kidney beans for extra protein and fiber.
Make it more filling: Add cooked pasta, rice, or quinoa toward the end of cooking.
Add greens: Stir in a few handfuls of baby spinach or chopped kale near the end.
Make it spicy: Add crushed red pepper flakes or a pinch of cayenne pepper.
Keep it vegan: Skip the Parmesan rind or use a plant-based alternative.

Common Questions

Can I put all the vegetables in the slow cooker at once?

You can, but I recommend adding the zucchini, peas, and corn toward the end. This keeps them from getting too soft while the potatoes and carrots finish cooking.

Do I have to sauté the vegetables first?

No, but I recommend it. Sautéing the onion, garlic, and tomato paste adds more flavor to the broth. If you’re short on time, you can skip this step and add everything directly to the slow cooker.

Can I make this vegetable soup ahead of time?

Absolutely! This is a great soup to prepare ahead because the flavors develop as it sits. Store it in the fridge and reheat when ready to serve.

Can I use frozen vegetables?

Yes! Frozen peas, corn, green beans, and mixed vegetables work well. Add the quicker-cooking vegetables toward the end so they don’t become mushy.

What to Serve With Vegetable Soup

This soup is hearty enough to enjoy on its own, but I love serving it with warm, crusty bread or a slice of homemade garlic bread. A grilled cheese sandwich is another great option, especially for a cozy lunch.

Storage and Reheating

Fridge: Let the soup cool and store it in an airtight container in the refrigerator for up to 4 days.
Freezer: Freeze in individual portions or freezer-safe containers for up to 3 months. Leave a little room for expansion. The potatoes and zucchini may become softer after thawing.
Reheating: Warm on the stovetop over medium heat or in the microwave until heated through. Add a splash of broth or water if needed.