How to Make Low-Sugar Jam

Strawberry Jam

It’s strawberry season in Texas! Every year I drag my kids to the berry farm to pick strawberries. It’s only fair since they’re the ones who eat most of them!


It might not be berry season yet where you live, but it will be soon enough. Jam is my favorite way to keep that juicy goodness all year long. Some people really love freezer jam, and while it does taste fresh and lovely, I have very little freezer space that I can spare. Plus freezer jam is usually runny.

I prefer traditional jam that sits on a shelf like a glass-enclosed jewel waiting to be plucked and opened and slathered onto freshly baked bread;  or onto boring PB&J’s. Whatever. The prepper in me demands something that will last nicely even when the power goes out.

I have been making jam for years. Did you know that my jam even won blue ribbons at the State Fair? It did! And that was probably the proudest moment of my life.

Here’s the thing about jam: it’s full of sugar. Like, more sugar than fruit. For real. Even a sweet-lover like me was a little horrified at the amount of sugar required in every single recipe. It’s not like strawberries aren’t already sweet!

You might think, “I’ll  just make a regular batch of jam with way less sugar!”  It doesn’t work that way, my friend. The pectin (that’s the stuff that makes jam thick and jelly-ish instead of runny and syrupy) only works when there is at least as much sugar as there are berries. Bummer.

Fortunately there is another kind of pectin that is especially for lower-sugar recipes (or even sugar free!). Most grocery stores don’t sell it because, well, nobody even makes the regular kind of jam anymore. Just me and a few old ladies. But I have found this other kind at Sprouts and Whole Foods (in the spice aisle) and on Amazon. It’s called Pomona’s Universal Pectin. A box of this should make jam with at least a dozen cups of berries.


Besides berries, sugar and pectin you’re also going to need some jars to make jam. You can get jars at any grocery store. I, however, like pretty things so I bought these dandy jars made by Weck. It’s a German company but they have offices in America so you can order them here for a couple of dollars per jar (plus shipping!). They’re not as cheap as Ball or Kerr jars but I think their style makes up for the price difference. I’ve had my jars for over ten years so I have more than gotten my money’s worth. (The jars in the pictures are the Deco style, 1/5 liter size.)

Weck canning jars deco

I actually prefer my Weck jars. They have a rubber gasket like Ball canning jars (You probably didn’t notice that there’s a rubber seal on the bottom of those metal lids, did you?). And instead of having a screw-on ring, you simply pop two metal clips onto the glass lid. These stack a lot better than traditional canning jars and did I mention how much cuter they are?

When I make jam I use my Weck jars but I also use a couple of small traditional jam jars too. I always end up giving some jam away and I don’t like to give out my Weck jars. I horde those for myself.

No matter which kind of jar you’re using, you’ll need to get them as clean as possible. They don’t need to be surgically sterile, but squeaky clean is good. The best thing is to put them into your dishwasher and run them on hot (soap isn’t necessary unless they’re really dirty).


Next you’ll need to put a gigantic pot of water on to boil. The biggest pot you own. You can actually get a pot just for canning and they’re not very expensive. My pot came with this wire rack so you can put jars in two layers and thus be done faster. Keep the lid on so the water doesn’t evaporate. You’ll need this to be boiling in a half hour or so.


While the water is heating on the stove and your jars are getting clean and hot, you need to get started on the jam. You’ll begin with the pectin. Using Pamona’s pectin is a two step process.  First, you’ll have to mix some stuff from the calcium packet into water. Super hard, I know. This calcium mixture can be saved in your fridge for several months so keep it if you plan on making jam more than once.


Next is the most boring, dreadful part of all: cutting up the strawberries. If your kids thought that picking them was hard, wait til they have to cut these suckers up! You are going to make your kids help, right? Sure you are!  If you are hoping to win some awards or enter your jam in a fair, you’ll want to cut your berries up into neat little pieces. If you’re making this for your family, it’s a lot quicker to throw the berries in the food processor for a couple of seconds. But don’t cut them up too much! It’s better to have a few large chunks than too many tiny ones.


Once they’re all cut up you have to measure the strawberries. Since the entire jam making recipe depends on how many cups of fruit you have, this is very, very, very important.


The nice thing about Pamona’s pectin is that you can make several batches at once. This is not recommended if you’re making traditional jam; you shouldn’t make more than double a traditional recipe. Probably because nobody has a big enough pot to fit all that sugar in!

Next you’ll put all those cut berries into a big pot. You’ll measure out the proper amount of calcium water. . .


You’ll add some lemon juice (the kind from concentrate is best because it’s potency is very consistent. With actual lemons you never know which ones are going to be extremely tart and which ones will be more sweet). Lemon juice adds a nice counterpoint to all the sweetness plus it helps the fruit keep its color.


You’ll add a smidge of almond extract (seriously, a smidge. I’d say 1/8 teaspoon per cup of berries). . .


And a bit of butter (around a 1/4 tsp per cup of berries).


(See how there’s white stuff in my berries? I totally messed up and added the sugar too soon. So I scooped it out. Don’t add your sugar til later!)

Now put your pot o’ berries on the stove on medium and let it heat up til it gets to be a rolling boil. (A rolling boil is one that keeps boiling even if you stir it). It’ll start getting all frothy.


Once it’s boiling, mix the sugar and pectin powder (it was in the other packet in the Pamona’s box) together in a bowl. I like to cut the amount of sugar to about  1/4-1/3 of the amount of berries. So if I have 12 cups of cut berries, I add about 3-4 cups of sugar.  Then dump the bowl of sugar and pectin powder into the berry pot and keep stirring as you bring it to a boil again.


After it’s come to a boil, take it off the heat and get all your jars set up. You’ll need a shallow pan of water to simmer your lids/rubber gaskets. These stay warm in the simmering water until you need them.


Line up all your jars. If you have a canning funnel, use it! It doesn’t quite fit into the Weck jars, but it does an OK job of keeping hot jam off the outsides.


A ladle is awfully handy too.


Scoop enough jam into a jar to fill it to 1/4 of an inch from the top. You don’t want jam to go to the very top or it will keep the lid from fitting snugly.


Keep filling all your jars. If you have one that isn’t full and all the jam has been divvied up, just put a lid on it and stick it into the fridge. You’ll use that one first! No need to process it!


You may notice that you made a horrible mess. That’s how jamming goes.

The next step is very important because the lids won’t seal properly without this: you need to take a hot, clean washcloth and wipe the jam from the lip of each jar.


See that blob of jam on the edge of that jar? That’s a no-no.

Once the jars are full and edges are clean, you’re going to put on the lids. If you’re using traditional jars, that means putting on the metal lid (which will be HOT because is been simmering on the stove), then screwing the ring on. Note: the ring should not be very tight. It should be screwed on just until it stops. Air has to escape in order for a seal to form and this can’t happen if the rings are screwed on too tightly!

If you’re using Weck lids, place them all upside down on your counter, then fish the hot rubber gaskets out of the simmering water. Place each ring over the raised part of the lid.


Then the lids get placed on the jar and two clips are put onto each jar, right across from each other.


Once the lids are secured onto the jars, into the waterbath they go. The water in your giant metal pot should now be boiling. If it’s not, crank it up until it is. The jam won’t get properly processed unless the water is boiling.

Jars should never be placed directly onto the bottom of the pot. There is sometimes a metal plate to keep them off the bottom that is included with the pot. If not, get an old washcloth to place on the bottom. This will keep the jars from constantly jiggling as they boil and possibly getting a crack or breaking outright. Keep the jars separate from each other for this reason too.

If your jars are short and you have the proper kind of insert, you can sometimes get the jars in the pot in two layers. The important thing is that the jars need at least 1″ of water circulating at the top.  If you can only do one layer at a time, it’s not a big deal.


Once the jars are in the waterbath, set your timer for ten minutes (you’ll need to add more time if you’re over 1000 ft altitude. Check online to see how much time to add).

After ten minutes, your jam is finished. A jar remover is incredibly helpful!


Let the jars sit on the counter until cooled. I usually make jam at night and let the jars sit until the next day.

As the jars cool, I like to gently shake them to disperse the fruit so that the larger pieces don’t stay at the top.

If you’re using Ball or Kerr jars you’ll hear a little metal “pop” as they cool. This is the suction sucking down the lids so you know if a good seal has been made. This is so satisfying. It worked!

Once your jam has cooled, it’s time for the moment of triumph! You’ll take the rings off each jar and wiggle the lid. If it comes off, your jam didn’t seal properly and you’ll need to put it in the fridge and eat it soon. If the lid won’t budge then your jam is good to go to the pantry! (In case you didn’t know, the metal rings are only meant to be used while you’re making jam. They serve no purpose when your jam is being stored because the lid will be held on properly by suction.)

If you’re using Weck jars, you’ll remove the metal clips, Wiggle the glass lids and they should stay stuck on strongly. Yay! It worked! In order to open the lids, pull on the little tab on the rubber gasket. As it stretches it will break the seal. Easy peasy. (Obviously don’t break the seal until you’re about to eat your jam.)

No matter which lids you used, always check before you open a jar to make sure the lid is on tight. If you grab a new jar out of the cupboard and the lid comes off easily,  throw that jam out! Unless you want to get food poisoning, that is!

You did it! You made jam from scratch. It’s not terribly hard, just a little bit complicated. But I’m telling you, every time you pull a jar off of the shelf you will feel a surge of pride that you did it! It’s just the best feeling in the world! Jam is the ultimate homemaker trophy. You’re in the big leagues once you start making your own jam!

P.S. Commercially prepared jam and jellies include one ingredient that you will notice your jam doesn’t have: red dye. Your jam looks bright red and luscious right now, but within a couple of months it will start to turn brown. There is nothing wrong with brown jam! It will still taste exactly the same, I promise. It’s perfectly safe to eat,  just a little ugly. So be forwarned. As long as the seal is good, your jam is perfectly safe. The pectin package suggests eating your jam within a year but I’ve eaten mine two years later and it’s been fine. Ugly, but fine.


2 thoughts on “How to Make Low-Sugar Jam

  1. I love Pomona Pectin and jam making! Our favorite is Sour Cherry. It’s just like eating cherry pie. So, very yummy!!! I also double, triple, whatever I can fit in the pot. I also do the lowest amount of sugar and don’t mind browning jam because it tastes so good. I did a bread making night (No-knead bread) for our women’s group and while the bread was good, everyone kept coming back for the jam. I think I brought Apricot, Strawberry and Sour Cherry. I’ll have to look up those Weck jars, so cute. Right now I’m just using regular jars but I try to keep the wide mouth ones…….even though my DH has given them away in an effort to share the jam love. Bless his heart. Your tut is well done. Thanks! Oh, there’s a lady I know that says that she buys the pectin parts in large bags at the Mennonite stores, of course that’s here in Missouri but if someone lives close to a community, they might be able to find it too.

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