Every summer, just as the fireweed starts painting the roadsides in shades of pink, I gather a basket and head out for one of my favourite preserving projects. If you’ve got a handful of fresh fruit and a sunny windowsill, you have everything you need to make beautiful, naturally thickened fruit preserves. I call it sun jam because it’s slow-cooked in the warmth of the sun instead of on the stove—and yes, it really works! In fact, it also creates the most delicious, fresh, and deeply coloured homemade jam you’ll ever eat, far better than anything from the grocery store.
This method is one of my favourite jam recipes, especially lovely with haskaps, which are one of the first berries to ripen here in our northern garden. They have that wild, tangy blueberry flavor and a deep purple color that makes the finished jam as pretty as it is delicious. However, you can absolutely make this with raspberries, strawberries, blackberries, or other different fruits—whatever’s in season near you.
Why Make Sun Jam?
Besides being low effort and totally charming? Ultimately, making sun jam is a wonderful project, especially if it’s your first time making preserves. For many people, this is the easiest way to start. Unlike traditional jam making, which often involves standing over a hot stove for a long time, using precise measurements, and adding much sugar, this method is far more intuitive and hands-off.
First of all, it preserves the bright, fresh flavour of the berries in a way that high-heat cooking sometimes can’t.
Additionally, it doesn’t require commercial pectin, instead relying on the natural pectin in the fruit, which is concentrated by slow evaporation.
Perhaps most importantly, you control the sugar. You only need enough sugar to help with preservation and taste; no extra is needed to get a set. You can start with just a fraction of what most recipes call for.
And finally, it feels like summer in a jar. It’s a slow, old-fashioned process that feels deeply rewarding.
What You’ll Need
2–3 cups fresh berries: (haskaps, strawberries, raspberries, etc.)
½–1 cup of sugar: This is a starting point. We’ll talk more about how to adjust this.
A small amount of lemon juice: Using juice from fresh lemons is best, as it adds both brightness and a touch of natural pectin.
A large bowl or dish: Glass or ceramic is essential as metal can react with the fruit’s acidity and affect the taste.
Cheesecloth or a clean tea towel: To protect your jam from dust and insects while it “cooks.”
Sunshine (or another heat source): A sunny window, a dehydrator, a low oven, or even a hot car will work!
Clean glass jars: A variety of sizes work well, from small jam jars to larger pint jars, depending on how you plan to use them.
Step-by-Step Instructions
Step 1: Mash the Berries. To begin, wash and stem your berries, then place them in your large bowl. For a chunkier texture, mash them gently with a fork or potato masher. If you prefer a smoother jam, you can pulse them a few times in a food processor—just be careful not to completely liquefy them! The goal is to break down the fresh fruit to release its juices.
Step 2: Add Sugar and Lemon. Next, stir in your sugar. I recommend starting with ½ cup of sugar per 2 cups of fruit. You can always add more later if you think it needs it. Add a splash of lemon juice, especially if your berries (like strawberries) are naturally low in pectin. Mix well until the sugar mixture starts to dissolve and looks glossy.
Step 3: Choose Your “Cooking” Method. Now, this is where the magic happens. Cover your bowl with cheesecloth to keep pests out while letting moisture escape.
Sunny Window Sill: The classic method. Set your dish in a bright window that gets several hours of full sun each day. Stir with a wooden spoon every now and then for even warmth.
Low Oven (for Cloudy Days): Pop your mixture into a low oven—around 170°F (or your lowest setting)—with the door cracked open slightly.
Dehydrator Tray: Spread your mixture thinly on a fruit leather tray. This method is faster, so keep an eye on it.
Your Car (Yes, Really): On a scorching hot day, your car dashboard can act like a mini greenhouse. Just crack the windows slightly for airflow.
Step 4: Check for Thickness. After that, depending on the method, your jam could be ready in a few hours or a few days. You’re looking for it to become thick, glossy, and reduced. To test it, place a small spoonful on a cold plate and see if it holds its shape. Once it’s reached a consistency you like, your hot jam is ready for the next step.
Step 5: Store Your Jam. Finally, spoon the jam into clean jars and let it cool. Because this is a low-sugar refrigerator/freezer jam, it needs to be stored in the cold. It will keep for a few weeks in the fridge. For longer storage, freezing is an excellent option, especially in pint jars with straight sides, which are less likely to crack.
Canning Sun Jam for Long-Term Storage (Optional)
If you’d like your jars of jam to be shelf-stable, you can process them in a hot water bath. For this method, using a bit more sugar (closer to 1 cup for every 2 cups of fruit) is recommended for better preservation.
Prepare your equipment. Wash your jelly jars and lids in hot, soapy water. Keep the clean jars hot in your canner water to prevent them from breaking when the hot jam is added.
Heat the jam. To ensure a safe canning process, you’ll need to bring your finished sun jam to a full boil on the stovetop over medium-high heat for at least one minute before canning.
Fill the jars. Ladle the hot jam into the hot jars, leaving ¼-inch headspace. Remove air bubbles by running a non-metallic utensil around the inside.
Seal the jars. Wipe the rims, centre the lids, and screw on the bands until fingertip tight.
Process. Using a jar lifter, carefully place the filled jars into your boiling water canner. Ensure the jars are covered by at least 1 inch of water. Process for 10 minutes (adjusting for altitude).
Cool. Turn off the heat and wait 5 minutes before removing the jars. Let them cool undisturbed for 24 hours on a towel.
Sun Jam
Ingredients
- 2-3 cups Fresh Berries
- ½-1 cup Sugar
- 1 tbsp Lemon juice
Instructions
- See above for more details for each step
- Mash the Berries
- Add Sugar and Lemon
- Choose Your “Cooking” Method
- Check for Thickness
- Store Your Jam
How to Use Sun Jam
This is a versatile preserve! Spread it on toast, swirl it into yogurt, or use it as a topping for crepes or ice cream.
Watch the Process!
Reading the steps is one thing, but seeing it all come together can make the process even clearer, especially if this is your first year making jam! Here is the full video of me making this beautiful sun jam.
Frequently Asked Questions (FAQ)
How is this different from jam from the grocery store?
Most store-bought jam uses commercial pectin and a high quantity of sugar. This homemade jam has a softer, fresher texture and taste, and you have complete control over the ingredients.
What if my jam is too runny?
It likely needs more time in the sun/heat to evaporate more water, or the fruit you used might be low in natural pectin. You can always add a small amount of lemon juice (from fresh lemons) or simply let it cook a little longer.
Can I make this with different fruits?
Absolutely! This method works beautifully with most berries. Stone fruits also work, but you’ll want to chop them finely. Experimenting with small batches is the best way to find your favourite combinations.
How should I store the finished fruit preserves?
If not canned in a hot water bath, it must be stored in the refrigerator or freezer. If canned, store your sealed jars in a cool, dark place like a pantry or cupboard.
Sun jam is a slow, simple way to preserve berries without fuss. It’s one of those old-fashioned techniques that just feels good to make—and even better to eat. And that deep, sun-ripened flavour? It’s hard to beat. Enjoy!