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Canning Strawberry Jam is a delicious, low-sugar, and fresh-tasting spread for toast, yogurt, or dessert recipes. Homemade strawberry jam is an amazing way to preserve the harvest and is a treat for the whole family. 

Three jars of homemade strawberry jam on a cutting board with strawberries and a spoon
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This low-sugar strawberry jam recipe is exactly how homemade jam should taste – not too sweet and tasting of summer. Unlike traditional strawberry jam, it tastes like fresh berries, not sugar.

This post is long because I have stuffed it full of information, tips, tricks, and hacks I have learned over 20 years of canning. I’m telling you EVERYTHING you need to know to be successful at making homemade strawberry jam in your very own kitchen.

You can always click “jump to recipe” if you’d like, but I highly recommend a read-through at least once to make sure you understand what is going on.

How to Use Pomona’s Universal Pectin

Each box of Pomona’s comes with two little packages; 1) calcium powder 2) and pectin.  

You mix 1/2 tsp of calcium powder with 1/2 cup of water. You won’t use it all for this recipe, but it can be stored in the fridge for 2-3 months.

Packets of Pomona's Pectin and calcium water on a grey cloth

How to Make and Can Strawberry Jam

*I’ll walk you through it here with some photos and tips, and you’ll also find a printable recipe card at the bottom of the post with exact measurements, etc. You can also click “jump to recipe” to skip down.

Canning Prep

Prepare your water bath canner by filling it with water, and setting it on the stove. Turn the burner to high. Once it reaches a boil, reduce it to simmer. You want to keep the water hot so that everything is ready when the jam is.

Wash and sanitize your jars. You’ll want to keep them warm to avoid having them crack when placed in the canner. You can fill them with hot water, or place them on a tray in the oven at 170˚F.

Wash your lids and set them aside in a clean place. You no longer need to simmer lids in water to keep them sterile. Woot!

Making Strawberry Jam

Rinse the strawberries. Remove the tops, and place in a heavy-bottomed saucepan. You can also “cheat” and start with Strawberry Puree if you already have some on hand.

Heat the fruit over medium heat until the juices start to bubble. If your strawberries are ripe you should not need to add any water to the pot. Just stir often to prevent sticking, and soon the natural juices in the berries will be released. Be patient!

At this point, you can mash the fruit with a potato masher, but I prefer to be lazy and use my immersion blender. Pro tip: blend about 30% of the strawberries, and just gently pulse the others, leaving some chunks. The goal isn’t to puree the fruit completely as that will impact the final texture of the jam.

Two photos of strawberries in a pot being crushed for low sugar strawberry jam

In a small bowl, combine 1/2 tsp calcium powder with 1/2 cup cool water. <–this comes in the box of low-sugar pectin.

In a separate bowl, combine sugar and pectin. Set aside. To prevent clumping in the fruit, Pomona’s must be mixed with your sweetener before being added to the fruit.

Add the bottled lemon juice and calcium water to the pot with the strawberries, and stir.  Add the sugar/pectin mixture, and bring everything to a rolling boil. Stir the mixture constantly for 3 minutes, turning down the burner to medium if the jam starts popping.

Pro tip: actually set a timer and stir for the full three minutes. The constant stirring prevents the jam from burning, and the cooking time is important to help the jam set.

Pro tip #2: a rolling boil means no amount of stirring will stop the bubbling. Use a long spoon or spatula to avoid any jam popping onto your hand. Dibs on “Jam Hand” as a band name.

At this point, turn the burner under the canner back up to high and get that water boiling again.

Remove the jam pot from the heat, and stir it gently for 5 more minutes. At the end of the 5 minutes, skim off any foam that remains.

Three photos showing how to make low sugar strawberry jam

Using the funnel and a ladle, add the jam to your prepared jars, leaving 1/4 inch of headspace at the top. Headspace is the amount of room between the top of the food, and the top rim of the jar.

Using a wet clean rag, wipe the rim to make sure there isn’t any sticky jam on there. 

Place a new clean lid on the jar and then a canning ring. Tighten the ring to fingertip tight (tight enough that it won’t come off, but not so tight that a normal person couldn’t budge it).

Three photos showing how to fill and place the lids of jars of homemade strawberry jam

Using canning tongs, add your jars to the boiling water, and put the canner lid on. Pro tip: you must have at least 1 inch of water over the tops of the jars for safe canning. Processing times will vary based on altitude. See the chart below.

Processing Times for Strawberry Jam

Processing Time for Strawberry Jam
Process Times at Altitudes of:
Style of Pack Jar Size 0-1,000 ft 1,001-6,000 ft Aove 6,000 ft
Hot Half-Pints & Pints 5 min 10 min 15 min
*Source: National Center For Home Food Preservation

Remove the canner from heat, remove the lid of the canner, and let the canner sit for 5 minutes. Use canning tongs and remove the jars and place them on towels on the counter. Make sure you put them where they can be undisturbed for 12-24 hours.

After everything has cooled, check the seal by pushing down on the middle of the lid. If it doesn’t give way, it’s sealed. Label the jars, and store in a cool dark place for up to a year. If the lid bows a little bit, put that in the fridge and use it within 3 weeks.

Four jars of low-sugar strawberry preserves on a wooden board

Why Do I Have to Use Bottled Lemon Juice in Jam?

Fresh lemon juice is amazingly flavorful, but it’s not meant to be used in canning. The acidity of individual lemons can vary, but bottled lemon juice is consistent.

The natural pectin in the strawberries and the Pomona’s react to the citric acid in lemon juice and create an amazingly fresh-tasting jam. The lemon flavor is not overwhelming in the jam, but it brightens the natural flavor of the strawberries and improves the overall flavor without needing extra sugar.

Common Strawberry Jam Issues

Help, my jam didn’t set!

I have found with Pomona’s that every batch has set because it doesn’t depend on sugar to create the gel. If you’re using another brand of pectin, the common reason for the jam not setting is that it wasn’t cooked long enough or the (appalling) amount of sugar called for was adjusted.

Jam must be fully cooled in the jars for 24 hours before it is determined if it has truly set. It will thicken as it cools.

If your jam truly looks liquidy after 24 hours, Pomona’s has an amazing step-by-step guide on their site for troubleshooting and fixing jam issues.

How to test to see if the jam is set – spoon/sheet test

If you want to double or triple-check that your jam will set before canning it, try the spoon/sheet test. Stir a metal spoon into the jam and hold it sideways above the pot. If the jam runs off in drips, then keep cooking it. It’s just not ready.

But, if the jam drops start to run together and come off the spoon in a sheet, your jam is done! Yay!

Help, the Bottom of My Jam Jar is All Juice!

Been there, jammed that.

Once your jam has set, there may be some settling happening in the jar. That’s normal! But sometimes, what the final product looks like is strawberry liquid on the bottom and actual jam on the top. 

This occurs when the strawberries were over crushed/smushed and too much juice was released. If you’re using a potato masher to process the strawberries, do so one layer at a time.

Can Strawberry Jam Be Doubled?

Yes, but jam is best when made in small batches. With that in mind, doubling the jam recipe is fine but tripling is not advised. You’ll want to double each of the ingredients, including the pectin.

Making Jam With Frozen Fruit

YES, you can use frozen fruit for making jam. Hurray! Check out this post on how to freeze strawberries if you have lots of leftover fresh berries.

Homemade Strawberry Jam Recipe Notes

  • The mixed calcium water will last for three months in the fridge. Shake well before using it for other recipes.
  • You can reduce the sugar to 1 cup if desired but you would need to cook the jam down for 8 minutes instead of 3.
  • You can sub in honey if you’d like. Use 1 cup for this recipe. As the jam is cooked and then processed in the canner, any beneficial properties of using raw honey will be eliminated.
  • Try adding some chopped rhubarb for strawberry rhubarb jam. Related: Freezing Rhubarb
  • If you don’t have enough jars to fill the canner, consider Canning Water in a few jars to stock your emergency drinking water supplies.
Three jars of homemade strawberry jam with fresh strawberries on a white board
4.92 from 12 ratings

Canning Strawberry Jam

Servings: 5 8 oz jars
Prep: 20 minutes
Cook: 20 minutes
Canning Time: 10 minutes
Total: 50 minutes
Canning strawberry jam is a delicious, low-sugar, and fresh-tasting spread for toast, yogurt, or dessert recipes. Homemade strawberry jam is an amazing way to preserve the harvest and is a treat for the whole family. 

Ingredients 

  • 8 cups strawberries {tops removed (~4 pounds)
  • 2.5 tsp Pomona’s Pectin
  • 2.5 tsp calcium water {from Pomona's Pectin box}
  • 1.5 cups sugar
  • 1/4 cup bottled lemon juice {do not use fresh}

Instructions 

Prep for the canning part

  • Prepare water bath canner by filling it with water, and setting it on the stove. Turn the burner to high. Once it reaches a boil, reduce it to simmer. You want to keep the water hot so that everything is ready when the jam is.
  • Wash and sanitize your jars. You can fill them with hot water, or place them on a tray in the oven at 170˚F degrees.
  • Wash your lids and set aside in clean place.

Making Strawberry Jam

  • Rinse the strawberries. Remove the tops and cut in halves or quarters (8 cups total). Place in a heavy-bottomed saucepan.
    8 cups strawberries
  • Heat the fruit over medium heat until the juices start to bubble. At this point, you can mash the fruit with a potato masher, or use an immersion blender (only blend ~30% of berries).
  • In a small bowl, combine 1/2 tsp calcium powder (comes in the box of pectin) with 1/2 cup cool water.
  • In a separate bowl, combine sugar (1.5 cups) and pectin (2.5 tsp). Set aside. To prevent clumping in the fruit, Pomona's must be mixed with your sweetener before being added to the fruit.
    1.5 cups sugar, 2.5 tsp Pomona’s Pectin
  • Add the lemon juice (1/4 cup) and calcium water (2.5 tsp) to the pot with the strawberries, stir. 
    1/4 cup bottled lemon juice, 2.5 tsp calcium water
  • Add the sugar/pectin mixture, and bring to a rolling boil. Stir constantly for 3 minutes, turning down the burner to medium if the jam starts popping.
  • At this point, turn the burner under the canner back up to high and get that water boiling again.
  • Remove the jam pot from heat, and stir gently for 5 more minutes. At the end of the 5 minutes, skim any foam that remains.
  • Using the funnel and a ladle, add the jam to your prepared jars, leaving 1/4 inch of headspace at the top. Headspace is the amount of room between the top of the food, and the top rim of the jar.
  • Using a wet clean rag, wipe the rim to make sure there isn't any sticky jam on there.
  • Place a new clean lid on the jar and then a ring. Tighten the ring to fingertip tight.
  • Using canning tongs, add jars to the boiling water, and put the canner lid on. Pro tip: you must have at least 1 inch of water over the tops of the jars for safe canning.
  • Process half-pints and pints based on the elevation guide below:
    *0-1,000 ft – Half-Pints & Pints =5 min 
    *1,001-6,000 ft – Half-Pints & Pints =10 min 
    *6,000 ft+ – Half-Pints & Pints =15 min 
  • Once the jam has processed for the appropriate amount of time, remove the canner from the burner, and carefully remove the lid of the canner (Pro tip: use oven mitts to take the lid off because the steam is super hot).
  • Using canning tongs, carefully remove the jars, and place them on a thick towel in a place where they can be undisturbed for 12 hours.
  • After the jars have rested for about 12 hours, press down in the middle of each lid. If it "gives" at all, the jar didn't seal. Either enjoy it that day, put it in the fridge, or reprocess it.
  • Once the jars have sealed and cooled, remove the rings. Label and store sealed jars in a cool (best results are 50-70˚F) dark place for up to 12-18 months.

Notes

  1. Makes 5, 8 oz jars.
  2. 8 cups fresh strawberries generally equal about 5 cups of mashed berries.
  3. Jam is best when made in small batches. Avoid doubling or tripling the recipe.
  4. Will last for 2-3 weeks in the fridge or 12-18 months sealed and at room temperature.
  5. Nutrition values are an estimate only

Nutrition

Serving: 1tbspCalories: 24kcalCarbohydrates: 6gProtein: 1gFat: 1gSaturated Fat: 1gSodium: 1mgPotassium: 29mgFiber: 1gSugar: 6gVitamin A: 5IUVitamin C: 11mgCalcium: 3mgIron: 0.1mg

Nutrition information is automatically calculated, so should only be used as an approximation.

Additional Info

Course: Canning
Cuisine: American
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About Sarah Cook

I'm here to help you make easy, seasonal, and no-fuss recipes for yourself and your family.

Whether it's a quick one-pot dinner or if I am teaching you how to can and preserve local produce, you can consider me your elder millennial grandma

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55 Comments

    1. Hi Faith, yes you can use 4 oz jars. It would be the same processing time as the half-pints or pints, which depending on your elevation would be 5-15 minutes.

  1. I just made the low sugar strawberry jam and it is delicious. I might have to make a another batch tomorrow. Thank you for the recipe and all your hints.

    1. I’m honestly not sure. I wish I had an actual answer for you.

      It will still be very edible, but I’m not sure what the texture will be like.

  2. Has anyone used frozen strawberries for this? If so, was the extra water content from thawing an issue? I’m about to make this tonight and only have frozen! My Pomona’s is supposed to be here today (thanks Amazon!) and I’m nervous because I have only ever used Sure Jell for jams. I have had it with the insane sugar needed though so I am ready to try something new and, hopefully, better for you! (My fiancé has an utterly RIDICULOUS sugar addiction and I am trying to cut it WAY back in everything in the house. Hopefully without him noticing much. I swear he is 54 going on 10 when it comes to sugar! It’s terrible!) Any advice you can give a girl about Pomona’s or frozen berries is appreciated!

    1. Shannon, I have made it with frozen strawberries lots of times. Discard the liquid they produce when they thaw (or set it aside to use with sparkling water) and then make the recipe as directed.

    1. Hi Christen, there is a note about that in the body of the post. I’ll c/p below. Please let me know if you have any questions!

      WHY DO I HAVE TO USE BOTTLED LEMON JUICE IN JAM?
      Fresh lemon juice is amazingly flavorful, but it’s not meant to be used in canning. The acidity of individual lemons can vary, but bottled lemon juice is consistent.

  3. Hi! I made the low sugar strawberry jam yesterday. I opened a jar to try today, and it’s delicious. I just have one question. Somehow I missed the step where you take the canner off the heat and let it sit for 5 min. I took the jars out after 10 min processing. Should I redo it? Let me know! sue 🙂5 stars

    1. I know I answered this question via email but I also want to answer it here in case anyone has the same questions. As long as they sealed they will be safe! The 5 min is really just to see if the texture/thickness is how you want it. If you skipped it, the jam will still be safe to eat.

  4. Hi Sarah. Relatively new to canning, and the low sugar Pamona’s approach seems to be a fun and easy way to get better.

    Question: You call for 8 cups/4 pounds. At the end of the recipe you share that 8 cups becomes about 5 cups ‘mashed’. I’ve topped and cut as you instructed and 8 packed cups of these cut (not mashed) berries weigh 2lbs 11 oz. I’m confused as to what weight/volume to go with. Any advice?

    1. In this instance, go based on cup measurements. It is impossible to find consistent weight measurements for produce because storebought vs homemgrown is going to be vastly different.

      You just need 5 cups of smashed and you’ll be good to go!

  5. I use a pressure canner Instant pot to can my recipes. Would it be ok with this Jam? If so do you still cover with water an inch over top of jars?

    1. Vicki, I don’t have enough experience with that device to say if it is safe or not. My Instant Pot specifically says do not use it for canning.

      You could also freeze the jam or use a regular stockpot with a small rack on the bottom.

    2. Instant Pots are not advised for canning! Please do not use one for this purpose. Most specifically state not to do this in the booklet that comes with it.