The fruity taste of strawberries really shines in this low-sugar strawberry freezer jam made easy in the microwave. Plus tips + tricks for setting jam!

Close-up of a glass jar of homemade strawberry freezer jam.

One of the supermarkets in my area had a ridiculously good deal on strawberries. $3.99 per flat! For those who don’t know, a flat is 8 pounds of strawberries! I needed some fruit for a party I was having, but there was plenty to spare, so I decided to make some freezer jam.

Top view of an open jar of low-sugar strawberry jam with a spoon inside.

Low-Sugar Strawberry Freezer Jam

I searched for a good recipe, and found some I liked, but was shocked about the amount of sugar in almost every recipe I found. I wanted a low-sugar strawberry freezer jam, so I decided to try and make it with less sugar.

At first, it was unsuccessful, which I am sure had nothing to do with the sugar and I will tell you why in a minute.

I ended up with jam that separated as soon as I poured it into my jars: fruit on top and liquid on bottom. I knew it wasn’t going to set, so I added more Pectin and re-heated my mixture, and it worked great.

Low-Sugar Strawberry Freezer Jam

The Science of Sugar and Pectin in Jam

Sugar draws liquid from fruits, which is also known as maceration.

When my low-sugar strawberry freezer jam was still runny after my first attempt, the fact that I used less sugar had nothing to do with it. After all, I had used less sugar, so hypothetically, there wouldn’t have been as much liquid drawn from the fruit, right?

Maybe or maybe not, but none of that mattered anyway because the sugar is not going to make a jam more thick or less thin; it’s not a thickening agent. The Pectin is the key thickener in jams.

Fruits naturally have Pectin, but the riper the fruit, the less Pectin the fruit naturally has. Strawberries are already lower on the Pectin spectrum.

Heat makes Pectin form into a gel. So when I added more Pectin and re-heated my mixture, the heat helped the Pectin gel up and it worked beautifully.

Top view of low-sugar strawberry freezer jam with a spoon inside.

Tips and Tricks to Setting Jam

I am pretty confident in saying, if you have runny jam, extra Pectin (start with 1 Tbsp more) AND Heat will fix your problem.

Here is some Pectin, fruit, and jam science facts for you:

“When dissolved and let cool, Pectin forms invisible strands that hold liquid in. Acid (such as lemon juice) helps draw even more Pectin out of fruit when it is heated. Water is attracted to sugar. Adding sugar causes some water to be drawn to the sugar molecules, leaving the Pectin molecules free to more easily get at and bind with each other, setting the preserve.” (Source:

So now that you know why you might be having problems with strawberry jam setting, you can go ahead and try this recipe! I hope it brings you success!

An open jar of thick strawberry freezer jam.

Ingredients for Low-Sugar Strawberry Freezer Jam

Ingredients for low-sugar strawberry freezer jam. Strawberries, granulated sugar, low/no sugar pectin, and lemon juice.

For this low-sugar strawberry freezer jam recipe you need four ingredients.

  1. Fresh Strawberries
  2. Lemon Juice
  3. Low/No Sugar Pectin
  4. Granulated Sugar

How to Make Strawberry Freezer Jam

Four image collage of recipe steps to make strawberry jam. 1- Crush strawberries in food processor. 2- Add pectin and lemon juice. 3- Add sugar. 4- Cook in microwave.

To make the strawberry freezer jam, you will:

  1. Crush the strawberries by pulsing them in a food processor or blender. Do not purée completely.
  2. Stir in the lemon juice and pectin. Let sit at room temperature for 20 minutes.
  3. Add the sugar and stir until mostly dissolved.
  4. Heat in microwave on high for 10 minutes until boiling and foamy.

How to Tell if Your Freezer Jam will Set

Once the jam has boiled sufficiently, the best way to tell if it will set is looking at the mixture from the side.

It’s best if you use a clear bowl to cook it in. You can also look through the container you will be storing the jam in, as long as it is clear.

If the mixture has a consistent texture of fruit and liquid throughout, it should set properly.

If the mixture separates into liquid on bottom and fruit on top, you will need to add additional pectin (1 Tablespoon) and bring the mixture back to a boil. Then check it again.

Crushed strawberry jam after being cooked in the microwave. Skimming the foam off the top.

Filling the Jars

  • Once the jam mixture looks consistent, skim the foam off the top and discard it.
  • Use a ladle and funnel to fill jars, leaving 1/2-inch head space for expansion.
  • Immediately top with lids and let stand at room temperature for 1 to 2 hours to cool down before placing in the freezer.
Pouring strawberry mixture into glass jars for freezer jam.

Will this Recipe Work with Other Fruits?

Yes! Just keep in mind the natural pectin in the fruit you are using and adjust the pectin as needed. Check out this pectin chart to help you. We’ve tried this recipe with strawberries and peaches.

Low-Sugar Strawberry Freezer Jam

How to Store Freezer Jam

You can store this un-processed strawberry freezer jam in the fridge up to 3 weeks or in the freezer up to 1 year.

It’s best to use a freezer-safe container. Here are some options:

  • Glass Mason Jars – are freezer safe as-is. I prefer to use the 8 oz jars, or half-pint size. The mini 4 oz jars are so cute and great for gifting. Stick with brand names here, Ball or Kerr have been around for years and make quality products.
  • Plastic Lids – You can use the lids and bands that typically come with the glass mason jars, but since you are not canning this strawberry freezer jam, I prefer to use these screw on plastic lids that come in regular or wide mouth.
  • Plastic Jars – If freezing glass makes you nervous, try these Ball Plastic Freezer Jars or these Screw Lid Freezer Containers.

NOTE: Be sure to add the date to the jar so you know when you made it. ( I write the date with a sharpie onto some masking tape attached to the lid.)

Mason jars filled with homemade strawberry jam.

More Strawberry Recipes

Looking for more ways to use a lot of strawberries? Try these strawberry recipes:

If You Make This Recipe, Please Rate and Review it in the Comments Below. THANKS!

Top view of an open jar of low-sugar strawberry jam with a spoon inside.

Low-Sugar Strawberry Freezer Jam

Prep Time: 10 minutes
Cook Time: 10 minutes
Inactive Time: 20 minutes
Total Time: 40 minutes
Yield: 5 half pints (8oz jars)

The fruity taste of strawberries really shines in this low-sugar strawberry freezer jam made easy in the microwave.


  • 4 cups crushed strawberries (about 2 lbs strawberries)
  • 2 Tablespoons lemon juice
  • 3 to 4 Tablespoons Ball Low or No Sugar Needed Pectin (equivalent to about 1 box Sure-Jell Less or No Sugar Needed Pectin)
  • 1 1/2 cups granulated sugar


  1. Wash, hull and crush strawberries in a LARGE (10 to 14-cup) microwaveable bowl to equal 4 cups. You may use a potato masher, food chopper, or food processor to crush the strawberries; do not puree--leave slightly chunky. Add lemon juice and Pectin. Mix well. Let it sit at room temperature for 20 minutes.
  2. Add sugar; stir until mostly dissolved. Heat in the microwave on high for 10 minutes until boiling and foamy. (Keep an eye on it so it doesn't boil over.) Remove and stir one last time. Mixture will still be thin.
  3. Skim the foam off the top, then pour jam into clean freezer containers leaving ½-inch head space for expansion. Your jam should look consistently chunky throughout the jar after it is poured into the jars. If the fruit has risen to the top and the liquid remains at the bottom, pour the fruit back into the bowl, add one additional Tablespoon of Pectin and heat again until boiling and foamy.
  4. Immediately top with lids and let stand at room temperature for 1 to 2 hours to cool down before placing in the freezer.


    • If you can't find low/no sugar pectin, you may substitute 6-8 Tbsp Ball Classic Pectin.
      • To store the jam: Refrigerate up to 3 weeks or freeze up to 1 year.
        • To use freezer jam: Pull from the freezer, allow to thaw in the fridge, and use like store-bought jam. (The freezer is for storing purposes, since the jam was not canned in a hot water bath.)

Nutrition Information:
Yield: 40 Serving Size: 2 Tbsp
Amount Per Serving: Calories: 53Total Fat: 0gSaturated Fat: 0gTrans Fat: 0gUnsaturated Fat: 0gCholesterol: 0mgSodium: 3mgCarbohydrates: 14gFiber: 0gSugar: 12gProtein: 0g

This data was provided and calculated by Nutritionix, and is an estimation only.

*Originally published 5/7/13. Photos updated March 2022.