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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.
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.
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.
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.
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).
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.
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.
Canning Strawberry Jam
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
- Makes 5, 8 oz jars.
- 8 cups fresh strawberries generally equal about 5 cups of mashed berries.
- Jam is best when made in small batches. Avoid doubling or tripling the recipe.
- Will last for 2-3 weeks in the fridge or 12-18 months sealed and at room temperature.
- Nutrition values are an estimate only
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
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