Blueberry Rhubarb Jam {for canning}

Published: Jul 20, 2022 · Modified: Jul 29, 2025 by jamjarkitchen · This post may contain affiliate links · 46 Comments

This delightful Blueberry Rhubarb Jam is a simple, no-pectin recipe made with just four ingredients for fresh, vibrant flavor. It's an easy way to capture summer's best produce and enjoy it long after the season ends. Perfect for spreading on toast, swirling into yogurt, or gifting to friends and family.

An open jar of blueberry rhubarb jam with a spoon inside sits on a wooden board next to slices of bread and butter, with sealed jars of jam in the background.

This Blueberry Rhubarb Jam has quickly become one of my new favorite canning recipes when rhubarb comes in season. While this combo may not be as commonly known as strawberry rhubarb, I actually prefer making rhubarb jam with blueberries. Not only do naturally sweet blueberries balance the tartness of rhubarb, but they also contain a good amount of pectin (which rhubarb does not), making this recipe easy to make without adding commercial pectin.

While there's nothing wrong with commercial pectin, and it can really reduce the time of jam making, it does require significant amount of sugar. Whereas in this no pectin recipe you can play around a little and adjust the sweetness to taste. *Although I do warn against leaving sugar out all together as you still need some to ensure a good gel.*

I hope you enjoy this blueberry rhubarb jam as much as we do!

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What is water bath canning?
Safe Canning Resources
More preserving recipes for you to enjoy.
Equipment
Ingredients
Recipe FAQs
Recipe

A jar of blueberry rhubarb jam with a spoon, sliced bread, and a slice spread with the jam on a wooden board; more jam jars and bread appear in the background.

What is water bath canning?

Canning is simply the process of applying adequate heat to high acid food that is sealed in jars for the allotted time necessary to kill off bacteria and micro-organisms that cause food spoilage. During heating, oxygen is driven out of the jars, causing a vacuum seal to form when the jars cool down. This prevents any outside micro-organisms and oxygen from getting back into the food. When done correctly, canning preserves food safely for at least a year, although probably much, much longer.

You can check out my guide on How to Safely Water Bath Can at Home more resources on safe home preserving.

Safe Canning Resources

If you are new to canning you can find great resources, recipes and tutorials at Ball Canning and the National Center for Home Food Preservation.

You can also check out my guide on How to Water Bath Can at Home.

More preserving recipes for you to enjoy.

Fresh rhubarb stalks, a bowl of granulated sugar, a lemon, and blueberries arranged on a gray surface—perfect ingredients for homemade blueberry rhubarb jam.

Equipment

For the Blueberry Rhubarb Jam.

Large pot or Jam pan
Cutting board and knife
Measuring cups
Potato masher: I like to use this to mash up the softened fruit for a smoother consistency. You could also just use a fork or even an immersion blender.

For Water Bath Canning.

Mason jars: Make sure the jars are clean and that the lids are brand new. You cannot reuse canning lids.
Large pot with rack OR Electric Canner: If you only can once in a while using a large pot with a canning rack works just fine. As someone who personally does a lot of canning and I absolutely LOVE my Ball FreshTech Electric Canner.
Jar lifter: You will need a jar lifter to remove the hot jars from the water bath.
Funnel: I personally love this canning funnel because it also allows you to measure the headspace easily.
Ladle: This Prepworks Canning Scoop is my favorite.

Ingredients

Rhubarb: Fresh or frozen both work. But make sure to thaw before using.
Blueberries: Fresh or frozen both work, just make sure they're thawed before using.
Sugar: White granulated sugar works best.
Lemon: I recommend both juice and zest for this recipe. But you can use bottled lemon juice in a pinch.

A close-up of a glass jar filled with blueberry rhubarb jam, with a spoon scooping some out; slices of bread are visible in the background.

Recipe FAQs

How will I know when the jam is set?

There are a couple ways to know when jam has reached its setting point.

The first is to check for something called "sheeting". For this method simply dip a spoon into the hot jam and then remove it turning so the jam runs down the back of the spoon. The jam is set when you see the drops hang on to the spoon, rather than just flowing down into the pot.

Another method is to pop a small plate into the freezer when you begin making the jam so it has time to get very cold. Then when you think the jam is ready simply spoon a little onto the cold plate and give a few seconds to set, then run you finger down the middle. If the jam immediately seeps back where you finger has been then it is not yet set. If the space your finger made remains clear then the jam is set.

Can I reduce the amount of sugar in this recipe?

Simply put, yes. Because you are not relying on added commercial pectin to set the jam you can adjust the sugar according to your preferred level of sweetness.

However, as the sugar still does contribute to ensuring a good set, if you reduce it too much it may result in a looser jam. If that's not a problem for you then reduce way. If you prefer a better set then keep the amount closer to what this recipe recommends.

Can I add additional fruit or flavors?

Yes, feel free to get creative with this jam. I personally love making it with a little nutmeg and vanilla extract. Cinnamon or cardamom would also be delicious.

A slice of bread with blueberry rhubarb jam sits on a wooden board beside a jar of jam with a spoon and several slices of bread in the background.

More berry preserve recipes to check out.

Slow Cooker Blueberry Butter

Mixed Berry Jam

Blackberry Preserves

Made this homemade Blueberry Rhubarb Jam recipe? Let me know what you think in the comments!

Recipe