How to make strawberry, raspberry and blackberry jam
What do you do when you get to the end of strawberry season but don't have enough berries for yet another batch of strawberry jam?
Updated May 2025
And they aren't as flavorful and juicy as they could be this late in the season. And maybe you're tired of strawberries by now, so you're tempted to take them out to the compost pile. (I know, but it happens.)
Learn how to preserve berries for the short-term, and how to make mixed berry jam.
Freezing berries for short-term preservation
My solution is to freeze those berries (or peaches or whatever fruit it happens to be) to be used in a different way in the future.
It happens often, at least to me: I'll have a cup or even a half cup of some kind of fruit, and I'm kind of tired of eating them plain. So I freeze them until another fruit comes into season so I can combine them into a delicious recipe.
I did just that with some bland strawberries a few years ago: I froze them until peaches were in season and made a batch of delicious strawberry-peach jam. Yum!
Now that we live where wild blackberry thickets threaten to swallow fields whole - I'm not kidding, some of them cover more ground than a house - I always save enough strawberries to make a couple of batches of this triple berry jam. Even when the strawberries are flavorful and juicy enough to eat whole.
Berries are easy to flash freeze by spreading in a single layer on a metal baking sheet in the freezer for a few hours. When frozen, they go in a zipper bag and back into the freezer. You can flash freeze them whole, or slice them up before spreading them on the cookie sheet.
When the next berry or fruit is in season, just pull out the frozen ones and combine them into this delicious jam.
Making jam with berries
Raspberry season is hot on the heels of strawberry season and then, finally, wild blackberry season arrives in mid-July, and then it's time to make strawberry, raspberry and blackberry jam! You'll find the directions inside boxes of pectin and at the Sure Jell website - they call it Triple Berry Jam.
Using pectin makes the "set" of jam (the thickness, if you will) more predictable and easier, but it's possible to make jelly and jam without pectin too. You do what makes you happy.
It's also possible to make your own pectin from apples, which contain a high amount of natural pectin. For instance, I don't use any added pectin when I make my harvest apple jelly. I didn't make pectin from those apples, I just didn't add any commercial pectin. The "set" was perfect.
Strawberries, raspberries and blackberries contain low amounts of natural pectin, so I do use commercial pectin when I'm making this mixed berry jam.
The recipe inside the box of pectin lists the ingredients as:
exactly 2 1/2 cups prepared* strawberries
exactly 1 1/2 cups prepared raspberries
exactly 1 cup prepared blackberries
*The directions define "prepared" as stemmed and thoroughly crushed berries.
Did you notice how many times it specifies "exactly"?
Since my husband doesn't care for blackberry seeds, I add filtered water to the fresh blackberries, mash them up and simmer for an hour or two, then strain out all the fruit pulp and seeds and use blackberry juice instead of berries in this jam - 1 cup of blackberry juice. ("Exactly" one cup of juice!)
In fact, the difference between jelly and jam is the presence of fruit "pulp". Jelly is made with juice, while jam is made with mashed berries or chopped fruit and juice.
For more information and directions see this post on making fruit syrup and my three favorite jelly and jam recipes.
Get ready to make mixed berry jam
I often make mixed fruit jelly, as well as this mixed berry jam, with bits of frozen fruit in my freezer. It's different every time I make it, but it's always delicious.
The first step to canning anything including jam is to sterilize the jars; I run mine through the dishwasher. I use half-pint jars for jam and jelly.
Keep your sterilized jars in a sink of hot water until the jam is ready to add to the jars. Hot jars + hot food = less chance of cracked jars.
Gather all the items you'll need - jar lifter, rings and lids that fit your jars, canning funnel, lid magnet-thingy.
Put the canning lids ("flats") in a pan of hot water to soften the rubber seals. Wash and dry the rings.
Add water to your water bath canner and bring it to a simmer so the water will be warm-to-hot when you're ready to add the jars. Once again: hot jars plus hot food plus hot water in the canner means less chance of jar breakage.
Make the jam
With all the preparation finished, it's finally time to actually make the jam. Sometimes it seems like the preparation takes longer than the actual making of things, doesn't it?
Mash the thawed strawberries with a potato masher. I use my mom's; I love using the kitchen utensils that were hers, and having that connection with her even though she passed away many years ago.
Measure the mashed strawberries and add to a large heavy pot. Then mash, measure and add the raspberries. Chop the berries really small; I wish I'd used smaller pieces in this batch.
Thawed berries are happy to release their juice faster and easier than fresh berries, a side benefit of freezing them instead of using them fresh.
Then mash and measure the blackberries if you're using berries instead of juice. I used a full cup of the blackberry juice I made, instead of using mashed blackberries.
Mix the pectin into the combined fruits.
Measure the sugar into a bowl. Personally I don't use as much sugar as the directions call for. I know the pectin directions say that you must use that much so it will gel correctly, but I like my jam soft-set anyway. And I just can't make myself use more sugar than fruit in jelly or jam.
Sure Jell also sells no-sugar pectin for use in low-sugar and no-sugar recipes.
Heat up the fruit and pectin mixture to a rolling boil, then add the sugar and stir it all together.
When the mixture comes back to a rolling boil, stir constantly while it boils for one minute, then take the pot off the heat.
Ladle the hot jam into the still-warm jars using your canning funnel, leaving 1/2" head space between the top of the jam and the top of the jar.
Wipe the jar tops with a clean damp cloth, add lids and rings, and put each jar in the canning pot using the jar lifter.
Actually, at this point, you have made jam, and canning is optional - although you'd have to store them in the refrigerator instead of on your pantry shelves.
But if you'd like to can your jam instead, so it's shelf-stable, keep reading! It will last longer if it's canned too.
Canning jam
Now that you've put the filled jars in the canning kettle, let's keep going!
Add additional hot water to the canning pot so there's at least an inch of water above the tops of the jars.
It's easy to tell how deep the water is: stick the handle of a wooden spoon (I used a black plastic one) in the water to the top of a jar. When you pull it out, the wet part shows you how deep the water is.
That's one of those "smack your head" moments, isn't it? That's how I felt when someone told me that trick! Genius!
Put the lid on your canning pot and bring the water to a boil.
Begin timing when the water comes to a full rolling boil and set your kitchen timer for ten minutes.
If you live more than 1,000 feet above sea level you'll need to add one minute, so set your timer for 11 minutes. Add another minute for every additional 1,000 feet in altitude. If you live 5,000 feet above sea level, you'll need to add give minutes to the recommended processing time.
Recipe Tips has a very comprehensive resource on processing times.
When the timer dings pull out the jars with the canning jar lifter and set them on a folded towel to cool. Oh, that pinging sound the lids make when the lids seal is like music to a canner's ears, isn't it?
Leave the jars undisturbed for 24 hours. Don't touch them until the 24 hours has passed. Then press lightly on the lid to test the seal. The lid should not pop up and down when you touch it. If it does, the jar didn't seal well and you should refrigerate it and use this jar first.
If the seal is good, wipe the jars with a damp cloth and remove the rings, label the jars and put them away in the pantry.
Label your jars! It only takes a few minutes and you'll be glad you did later - or sorry that you didn't. If nothing else, use a Sharpie to write the year and contents on the lid.
Why you'll love this jam
The flavor of this jam is deep and complex; I can taste the strawberries but not quite... the raspberries are there... the blackberries aren't overpowering. It's .... perfect.
I think their exact proportions are exactly right - except that they recommend too much sugar, that is.
However, if you're short of the amount of strawberries but have more blackberries than needed, go ahead and make this jam - it will still be delicious!
If you planned ahead, you also made a loaf of bread that morning. Maybe I should add "make a loaf of homemade bread" at the beginning of the jam-making directions?
Opening a jar of this jam brings back memories of sunshine and summer, and hot mornings spent picking berries in a far-out pasture (or a pick-your-own farm) while birds sang in the trees.
Maybe a bunny jumped out of the thicket right under your feet and startled you; maybe you came face to face with a deer or even a coyote as you rounded a corner of the thicket.
Maybe you came home with chigger bites. (All of those have happened to me.)
Even if you "picked" your berries at the grocery store, this jam will be delicious!
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