How to Make Slow-Cooker Ketchup

Next week we’re going to be talking all about canning, but I couldn’t resist getting a head start today with these gorgeous tomatoes and a fuss-free recipe for homemade ketchup.

If you have kids in your house, chances are ketchup is one of your most-used ingredients. And why not? Sweet and tangy, ketchup, like its originator the tomato, goes great on just about everything. These days the big-name ketchup makers have been paying attention to the organic and whole-food movements, and have started offering more natural versions of their product. That’s great, but if you’re like me, you might still want to control what goes into the food your child is obsessed with.

Luckily, ketchup is quite easy to make, especially if you employ a slow cooker. The most work comes from preparing the tomatoes, which can be done ahead of time if you’re like me and not quite as deft at coring and dicing. Ketchup is perfect for the slow cooker because it takes a long time to cook away the excess liquid. Cooking it low and slow, rather than quickly on the stove, will help bring out a depth of flavor that lets the summer tomatoes shine and makes ketchup even more delicious.

Tips and tricks

  • Paste tomatoes, such as roma or San Marzano, are often recommended for recipes like tomato sauce and ketchup. I like to use a mix of heirloom and San Marzanos tomatoes for ultimate flavor. Keep in mind that heirloom or slicing tomatoes are more watery, and will take longer to cook down.
  • Feel free to change up the spices, but don’t change the ratio of vinegar and tomatoes if you decide to preserve using a water-bath canner. Ph levels are an important part of keeping your preserved items safe. When in doubt, store in the fridge or freezer.
  • Leaving the skins on the tomatoes will provide added texture, but if you want a smoother product, gently boil the whole tomatoes in water for about 30 seconds, then place in an ice-water bath. Remove skins once cooled.
  • If you don’t have cheesecloth for the spice bundle, you can use an unbleached tea filter or metal tea ball.

Whether you call it ketchup or catsup, here’s how to make this indispensable condiment.

Slow-Cooker Ketchup

An easy way to make ketchup at home.
4.67 from 15 votes
Print Pin Rate
Course: Condiments
Servings: 4 cups
Calories: 157kcal
Author: Megan Myers


  • 4 pounds tomatoes paste or mixed variety
  • 1/2 cup chopped onion
  • 2/3 cup apple cider vinegar
  • 1/4 cup brown sugar
  • 2 teaspoons fine sea salt
  • 1 cinnamon stick crushed
  • 1/2 teaspoon whole allspice
  • 1/2 teaspoon whole cloves
  • 1/2 teaspoon peppercorns
  • 1/2 teaspoon celery seeds
  • 1 bay leaf


  • Remove tomato skins (if desired), core, and seeds, and chop tomatoes.
  • Place tomatoes and onion in slow cooker and set to high. Cook approximately 1 hour, until tomatoes have started to break down and the juices are bubbling.
  • Puree tomatoes using a stick blender or in batches with a blender. Return to slow cooker.
  • Stir in vinegar, sugar, and salt.
  • Place remaining spices on a square of cheesecloth and tie into a bundle with kitchen twine. Add to the mixture.
  • Cook on low, with the lid removed, for approximately 8 hours. Pour into either prepared glass jars for canning, or freezer jars.
  • Process in a water-bath canner for 15 minutes if canning. If freezing, let cool in freezer jars to room temperature before sealing and moving to freezer.


Depending on desired consistency, you might need to cook for longer.
You may cook on high to reduce to required time, but be sure to keep an eye on the ketchup and stir to prevent sticking or scorching.


Calories: 157kcal | Carbohydrates: 35g | Protein: 4g | Fat: 1g | Saturated Fat: 1g | Sodium: 1193mg | Potassium: 1152mg | Fiber: 7g | Sugar: 26g | Vitamin A: 3780IU | Vitamin C: 63.9mg | Calcium: 81mg | Iron: 1.6mg


Have you tried making condiments at home? What’s your favorite?

About Megan

Megan Myers is a copyeditor and spatula-wielding mom seeking out the simpler life in Texas. Her blog, Stetted, focuses on her family’s journey from junk food addiction to a diet of local, organic, and whole foods, while exploring the many options farmers provide.

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  1. I’ve made homemade dressing before but never ketchup. It sounds so good.

  2. Stonewall Kitchens sells ketchup and it is delicious…I never would have thought of making my own until I had tasted some really tasty ketchup. It makes sense, since homemade is better than store bought for some many items. I like the idea of using my slow cooker, thanks.

  3. I am going to pass this along to friends! What a great sounding recipe!

  4. I’ve mixed up my own ketchup from tomato sauce & vinegar, but hadn’t thought of starting with tomatoes! I have some paste tomatoes growing in my garden, so I’ll definitely give this a try!

    My trick for the texture (and easiness) is leaving the skins on, but giving it a whir with my immersion blender to make it all smooth when it’s done. I do it for tomato sauce or berry sauces.

    Do you know if this does freeze well?

    • @Mystie, I do freeze this. I recommend thawing it in the fridge, and then giving it a good stir before using it. Remember to use freezer-safe containers!

  5. This is the year that I’ll make ketchup, so thank you for this easy method. I haven’t bought commercially made jam in three years. This year, I’m making tomatillo sauce and salsa, because I use them all the time. Canning is a blast!

  6. Thanks for the ketchup recipe. I can’t wait for the canning post! It’s a new hobby of mine- I just bought my first canner.

  7. 5 stars
    This is great! I’m sure it taste much better then store bought brands too!

  8. This looks like a ketchup I might actually like! Thanks for sharing it.
    I have made relish with my mother-in-law, but since it’s something I don’t really like, I wouldn’t call it a favorite.

  9. I’ve made homemade mustard before, but have never tried ketchup. Your instructions are so clear, I absolutely must try this now. Thank you for putting the water bath canning info in there, too!

  10. looks so yummy- I might start actually eating ketchup!

  11. 5 stars
    Homemade ketchup and it’s made in the slow-cooker! I’m sold!

  12. This sounds yummy! Can’t wait to try it, once our tomatoes come in. The condiments I’ve made the most are things like plum sauce or apricot mustard. Never ketchup, though.

  13. I am so excited! My slow cooker is my favourite kitchen appliance, but I had no idea you could use it to make ketchup. Awesome. NOW if only I can get through the summer without all of my roma tomato crop getting blight!

  14. I made this ketchup yesterday, and it turned out great.
    Here are some differences I did: First, I drained off most of the liquid before using the immersion blender. The cooked tomatoes were so watery that I knew it would take forever in the slow cooker to cook down if I left all that liquid in. Second, I left my slow cooker on all day and night. I was using a mini slow cooker, so perhaps this is why it took so much longer to cook down.
    I only got a little over 1/2 pint from this recipe, so there would be no ketchup to freeze or can. I feel it was a good use of tomatoes for me, since I had them on hand, and I really didn’t want to do a big canning project. As far as being able to can enough homemade ketchup to last the year (which is my ultimate goal with all things canning), there would be no way. I only have about 12 pounds of tomatoes per week in the summer, so salsa, sauce and oven roasted tomatoes are more practical goals for me.
    Keep up the great recipes. I appreciate all recipes that include instructions for canning!

    • HippieSoul says

      In the summer when my tomatoes plants are producing lots of tomatoes I cut out the core and throw them into a freezer bag until I’m ready to use them. Throw the whole frozen tomatoes in the instant pot and they work the same as fresh. I do put my onion on the bottom of the show cooker under the tomatoes to give them a little browning and to help with not scorching my tomatoes. I also found if you’re ketchup doesn’t come out as thick as you want you can add a little corn starch (teaspoon to start with a cold tablespoon of your tomato sauce and more if it hasn’t thickened in 15.). I love the taste of this recipe and usually double the recipe and hot water bath jelly jars full of ketchup. Be sure and cook the ketchup for 15 minutes or so after adding the corn starch to get rid of the uncooked starch taste.

  15. I have made condiments – always my own salad dressing and salsa. I have made ketchup, though it didn’t turn out great. As you point out, it can be purchased with whole foods ingredients, but I might try this delish-looking recipe (never heard of slow cooker ketchup until now).

  16. Love this recipe… I’ve been meaning to try making ketchup at home. And, I love the use of the slow cooker. Can’t wait to give it a try!

  17. Heather Chester says

    I haven’t try making ketchup because I just purchase it in the department store. Since, I don’t know how to make this one and I don’t have a guide so I don’t give a try. It is my first time having read this sort of post so I will make this. It seems so interesting to try.

  18. It is my first time meeting a ketchup recipe so I will make this one this weekend. It nice to try I hope it will taste the same or better than the usual ketchup.

  19. I have a question. I have tomato puree the freezer from last year’s tomatoes. I’ve been looking for a recipe to use it. Your ketchup sounds wonderful, but I don’t know how much puree to use since I’m not starting with whole tomatoes. Can you tell me how much puree you get when you’ve cooked and pureed the 4 lbs of tomatoes? Thank you! I really want to try this.

  20. This sounds amazing. I must give this a try. Is it ok to double or even triple the recipe?

  21. The American Homemaker says

    I’ve never tried making my own ketchup… Guess it’s time! 🙂

  22. Wow, this recipe is amazing! I will be now be trying more condiment recipes after tasting how much better than store bought they can be, thank you.

  23. Can you use frozen tomatoes? I have 3 one gallon bags in my freezer.

  24. i thank you will like thes rec

  25. 5 stars
    My mother just dropped off around 8 pounds of tomatoes from her garden and I was debating between this and Salsa. Im thinking ketchup since I have pickled red onions and garden relish and Im craving burgers!

  26. 5 stars
    I just made this two days ago. The house smelled so good and the ketchup is excellent. Thank you for posting.

  27. 5 stars
    I almost forgot to mention that a tea ball works for the spices too. I ran out of cheesecloth.

  28. A trick I learned this summer while making fruit butters, and one that comes in handy when ‘cooking down’ in a slow cooker is placing wooden spoons or chopsticks between crock and lid to let steam escape, usually done in the last hours. My older crockpot doesn’t have a rubber gasket on the lid so naturally allowed steam to escape; however, the new crocks with that gasket definitely need that small escape. The heat, in my crocks, is still maintained.

  29. This article got my attention by the fact that its a “slow cooker”… will be interesting to see how the cooking time effects the flavor 🙂

  30. 5 stars
    I love, love, love this ketchup recipe. Thank you so much for posting it and including instructions to make it using a slow cooker. Saved me from standing all day in front of a hot stove last summer.

  31. 5 stars
    OMG Just finished canning the first two batches. I used organic roma tomatoes. I used a blender after step one then used a food mill. that really helped. They were on low all night. Nice and thick and the flavour is amazing. I wanted to bath in it. I have two slow cookers and made two batches. I almost think if the recipe was doubled, it may not reduce well and get thick. Used came sugar instead in one batch and raw sugar in the other. The taste was very similar so I will keep using cane sugar from the coconut tree. Does not raise blood sugars so better for me. Thanks so much for this recipe.

  32. 5 stars
    I’ve been using your ketchup recipe for a few years now. The ketchup smells great while its cooking and I like the taste of fresh, clean tomato ketchup to use throughout the year. I just shared a link to it in my one canning FB groups because a few people asked about the ketchup recipe I use. Thanks for creating the recipe!

  33. 5 stars
    Made this today, took about 10 hours on low to get to the consistency i wanted. Absolutely packed full of flavour. Ended up using a mix of tomatoes. Mostly Rouge de marmande and Green Zebra. But also added some San marzano and purple romas. Probably took longer because of the high water content of the green zebras.

  34. Jeremiah Rodriguez says

    5 stars
    Just tried this recipe last night with four varieties of heirloom tomatoes form my garden. Turned out amazing! Even my kids love it.

  35. Linda todd says

    We canned 60 qts of tomatoes last summer and I thought I’d try my hand at making catsup and using the left over canned tomatoes up before next crop. I’ve made sweet relish in the past few years and we absolutely love it.

  36. The flavor is amazing! I’m always a little worried about online recipes – is 15 minutes enough canning time? I just fear botulism.. I’m new to canning, by the way. I just see other tomato based products needing to be cammed for 45 minutes. Can you put my mind at rest?

    • Hi Cat, I believe the longer times with tomatoes are for raw tomatoes only. With ketchup, salsas, and sauces, you need less time because they are already cooked and hot. Does that make sense? The Ball Book of Canning is a great beginner resource!

  37. 4 stars

  38. I just discovered this website and will be making the catsup in a few minutes. I don’t have any apple cider vinegar, so can I safely substitute the regular white vinegar? Also I printed off the recipe for use in the kitchen and was very disappointed to see that a lot of the printing on the right hand side of the page is missing, so I had to copy that part out by hand. Is there anything that you can do to reduce the amount of space taken up by the printing and thereby get it all on the page without having to write it in by hand? In case you didn’t guess, computers and me don’t really get along. I was very pleased with myself for getting the website up and getting it printed off. Thanks.

    • Be careful in substituting the vinegar. Apple cider vinegar is recommended due to it’s sweet fruity tang. White vinegar may give your ketchup a clinical, hospital-like taste. It’s very sharp with little wiggle room or personality. If you’ll be using white vinegar, I would suggest steeping spices in it for two weeks before hand. This will help take the very “cleaning product” edge off the flavor and add additional seasoning to your ketchup. 🙂

  39. 4 stars
    I made this recipe yesterday with tomatoes from the farmer’s market. I love the flavor, although I might try adding just a little bit more sugar next time. I used a food mill to get a finer consistency (after the overnight cook) and I liked not having to monitor the ketchup for hours or use any thickeners. It has a real tomato taste, unlike the commercial kind.

    The recipe yielded about 12 oz of finished ketchup for me. Next time I would at least double it or triple it for more jars in the pantry.

  40. Michelle M Giroux says

    Do you need the spice of it can the slices just be mixed in?

  41. 5 stars
    I want to make this with white heirloom tomatoes and freak my friends out. I suspect it would have a creamy color, maybe a slight green hue due to the tomatoes, but still very pretty. It would have a very mild, sweet flavor, I think.
    Heirloom purple tomatoes with red onions could be really gorgeous too, with a much deeper richness. It would be nearly a burgundy color, close to wine red? Exceedingly tempted to make small experimental batches!

  42. 3 stars
    I tried to double this recipe, as I have tomatoes coming out of my ears. It didn’t work for me and after sitting in the crockpot all night I had to transfer it to the stove to simmer down. It tastes like sweet BBQ sauce, not ketchup and was dark brown. My husband thinks he would eat it, so we put it in the freezer, but it’s back to store-bought for my daughter (who eats ketchup on everything), as she thought it was too sweet – it’s definitely not, but I think the tang and the cloves were throwing her off. I think next I’ll bring my tomatoes to nearly a paste before adding the other flavors, and do it on the stove. I think the tomato variety we have is too watery.

  43. 4 stars
    A truly good recipe. I will be making it with ten 6-ounce cans of Contadina tomato paste. My goal is thereby to make tomato chutney. The tomato paste is, of course, richer and more concentrated. In every other way I will follow the recipe and the instructions for the slow-cooker.

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