This easy small batch rhubarb jam recipe is flavoured with juniper berries for a beautiful way of preserving rhubarb without pectin (includes canning instructions). This way you can enjoy this rhubarb throughout the year.
Wash five 250 mL jars and lids. Place the jars on a sheet pan in the oven and heat them at 250 °F to sterilize them while you make the jam. Keep the jars in the oven until you will use them. Keep the clean lids aside on the counter for later.
Combine the rhubarb, sugar, and juniper berries (if using) in a large, deep pot.
Cook the fruit and sugar mixture on medium heat to first dissolve the sugar.
Increase the heat to medium–high and continue to cook the jam, allowing it to come to a full boil, stirring with a wooden spoon so it doesn't catch on the bottom and burn.
The jam will bubble up high in the pot initially and then eventually settle again. Continue cooking the jam until it reaches about 217–220 °F or 103–104 °C (the jam setting point).
Divide the jam among the jars, leaving a ¼ inch headspace. Remove air bubbles, wipe the rims clean, then cover with the lids, fingertight. If any of the jars aren't filled full, don't seal them. Instead you can cover them and enjoy them right away, storing in the fridge. You will likely fill 4 to 4.5 jars.
Seal the closed jars according to the manufacturers recommendations. I used Bernardin jars and I boiled my jam jars for 10 minutes to seal them. You can also invert the closed jars and keep them upside down for a couple of minutes before flipping them right side up. With either method, a vacuum should form.
Let sit 24 hours undisturbed before storing them in the pantry.
Notes
I like to check the temperature of the jam as it cooks to ensure that jam reaches the jam setting temperature point so it sets properly in the end. A probe thermometer with a longer cable like the ChefAlarm would be great for this purpose!If you are looking for an awesome cookbook dedicated to homemade preserves, the Preservation Society book on preserves is my favourite and it's available on Amazon.For a less sweet jam, you can reduce the sugar to 500 grams but not less than that, if desired.