Canning Low Sugar Strawberry Jam is a delicious 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.
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Unlike traditional strawberry jam, this low sugar recipe is exactly how jam should taste – not too sweet and tasting of summer. 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 18 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 “jump to recipe” if you’d like, but I do recommend a read-through at least once to make sure you understand what is going on.
And if you get to the end of this and realize canning is just not your jam (<—-see what I did there…?), I have a Strawberry Freezer Jam Recipe, Blueberry Freezer Jam, No-Cook Raspberry Freezer Jam, and Blackberry Freezer Jam recipes that you’ll love! No cooking, no canning; just fresh tasting freezer jam.
Can I Use Regular Pectin for Low Sugar Jam?
Such a bummer, but no. “Normal” jam recipes need all that sugar for the jam to set. If you go and mess with the measurements, your jam won’t set up properly. But hey, then you can make strawberry syrup I suppose, or add it to Homemade Strawberry Ice Cream.
There are other low-sugar pectin brands that work well (Ball Low Sugar Pectin is great too!), but my heart belongs to Pomona’s because it has never once let me down. This recipe has not been developed for using Stevia and any substitutions will likely result in a different texture.
Most commercial pectins are added to fruit along with bonkers amounts of sugar to create a “gel” that makes jam, well, jam. Most conventional recipes call for at least a 1:1 ratio of fruit to sugar. That means for a recipe that makes five jars of jam, you’re looking at needing 6-8 cups of sugar. SIX CUPS OF SUGAR PEOPLE.
Pomona’s, on the other hand, is activated by calcium (not sure) and needs just a touch of sugar to work. :confetti: This recipe makes five (8 oz) jars using just 1.5 cups of sugar. Pomona’s is also gluten-free, vegan, certified kosher, and GMO-free. You can also use it in this Strawberry Rhubarb Jam.
How to Use Pomona’s Universal Pectin
Pomona’s comes with two little packages; 1) calcium powder 2) and pectin.
This is the calcium powder. You mix 1/2 tsp of it with 1/2 cup of water. You won’t use it all for this recipe; it’s gonna last you a long time!
Homemade Strawberry Jam Equipment
- Jars! Canning jars only (don’t use leftover mayo, jam, or pasta sauce jars from the store). I recommend 8 oz jam jars, or pints (16 oz for my American friends who like me, ignored learning this stuff in fourth grade) if your family goes through jam quickly.
- Clean, never before used canning lids
- Water bath canner or deep stockpot with a jar rack.
- Large saucepan. I adore my dutch oven for so many reasons, and jam season is another one of those reasons! Having a wide pot with high sides is best for making jam as it allows the jam to process at a rolling boil without slopping over the sides.
- Jar lifter
- Clean washcloths and towels
- Medium mixing bowl
- Knife and cutting board
- Comfy shoes
Check out this Canning Supplies and Equipment List for a detailed explanation of all the supplies and brands I recommend.
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 strawberry and improves the overall flavor without needing extra sugar.
How to Make Low-Sugar Strawberry Jam
*A detailed and printable recipe is available at the bottom of this post
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 170F.
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 the 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 totally as that will impact the final texture of the jam.
In a small bowl, combine 1/2 tsp calcium powder with 1/2 cup cool water.
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 lemon juice and calcium water to the pot with the strawberries, stir. 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. 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: 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 heat, and stir gently for 5 more minutes. At the end of the 5 minutes, remove 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 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 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).
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. Process (boil) for 10 minutes.
Remove the canner from heat, and let sit for 5 minutes. Remove the jars and place them on towels on the counter. Make sure you put them someplace 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.
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 the sugar to create the gel. If you’re using another 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, 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.
How Long Does Canned Strawberry Jam Last?
You can keep an opened jar of low-sugar strawberry jam in the fridge for a month. Sealed jars are safely stored at room temperature for up to a year.
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.
Low Sugar Strawberry Jam
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 200 degrees F.
- 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 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, remove 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 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 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 (boil) for 10 minutes.
- Remove the canner from heat, and let sit for 5 minutes.
- Remove the jars and place them on towels on the counter 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. If the lid bows a little bit, put that in the fridge and use it within 3 weeks.
- Label the sealed jars, and store in a cool dark place for up to a year.