Blackberry Jam


Last weekend I made blackberry jam and canned it! I had a blast and the jam is delicious. For me it was worth making despite the sugar because it reminds me of summers in Michigan at my Grandmother’s cottage. We traveled back almost every year when I was growing up and I loved walking through the woods out into the field with my Grandmother to help her collect wild dewberries (closely related to blackberries).

Back then that was the extent of my involvement in the jam making process. After returning to her cottage, I rushed back out to swim in the lake while my Grandmother spent time in the kitchen making batch after batch of jam. At the end of our visits she always gifted us a few jars of fresh Michigan jam to carry back with us to California.

Ever since I did a little reading about food preservation (motivated by our interview with Smokey Ridge Charcuterie), I knew I wanted to try canning. Since then I read the canning section in The Encyclopedia of Country Living, while at the same time bugging my wife to let me get some canning equipment. For Father’s Day she “surprised” me with twelve 8oz Ball canning jars and this Ball Jar Canning Utensil Set.


I’m having fun making my way through Carla Emery’s book, but I’d recommend a simpler more focused book like the Joy of Cooking All About Canning & Preserving which I picked up at our library along with the Grapes of Wrath and a cookbook by Chez Panisse Cafe. And with all of that said the actual recipe I followed is from The Fannie Farmer Cookbook (after all my Grandmother never put ‘tart green apples’ in her berry jam, and I’m pretty sure apples and berries aren’t in season at the same time!)

Side Note: Jam is pretty much the easiest and safest canning you can do. The key with any canning is to make sure your recipe is reputable (you can check recipes out here) and that you don’t deviate from it. For example, the sugar in jam recipes is the preserver. If you skimp on the sugar you weaken the shelf life and increase chances for spoilage. Finally low acidic foods (not the case with jam) require a pressure canner and are much more dangerous if canned incorrectly (botulism can kill you). Canning is safe if you follow the recipes.



  • 4 cups blackberries
  • 3 cups sugar (this is a ratio of 1.33, the USDA’s jam is a ratio of 1.5, but in the Fannie Farmer recipe the berry liquid is reduced before the sugar is added. By all means follow the USDA recipe linked above if you’d rather)
  • 4 8 oz Ball Jelly Jars with new lids (it’s OK to reuse rings)



Sanitize your clean rings and jars (DO NOT BOIL THE LIDS) by boiling them for 10 mins in a large pot of water. Turn off the burner under the pot when the 10 mins are up, but leave everything in the hot water until it’s time to fill the jars. The pot should have a wire rack at the bottom to keep the jars from touching the very bottom of the pot (I tried to use an upside down cake tin with mixed results). The pot should be deep enough so that you have room for at least 1 inch of water above the tops of the jars when they are sitting on the rack (my 5 gallon pot for making homebrew beer was deep enough).


Prepare your lids by letting them soak in a bowl of warm to hot tap water (very hot or boiling water ruins the seal).


Wash and clean your berries. Discard any berries that don’t look fresh. Add your berries to a large pot (not your canning pot) and mash them with a potato masher. Simmer the berry mash for 15 minutes. Add your sugar and bring to a boil while stirring constantly. Boil the berry and sugar mixture until it gets to 214°F on a candy thermometer. The thermometer is optional, but it’s also only $10 and will last a lifetime so I recommend taking the guess work out of it. Turn off the stove and skim off the foam from the top of the mixture.


Using canning tongs (or regular tongs) remove the sanitized jars from the canning pot and set them on your counter. Insert your wide mouth canning funnel and pour the hot jam into your jars until the jam is 1/4″ from the very top of the jar. (The Ball Jar Canning Utensil Set has a nifty tool for measuring the head space for any canning recipe). Place a lid on top of the jar. Screw a ring on until it is comfortably snug but not overly tight, which prevents it from sealing. Set the jar aside and repeat using the rest of your jars, lids and rings until the mixture is all used up.


Any left over partially filled jar (more than 1/4″ head space) should be placed in the fridge and used within a couple of months. The rest of the filled jars should be returned to the canning pot. Bring the pot back to a boil (add water if needed to get more than 1″ above the lids) and boil everything for another 10 minutes.

That’s all it takes. The next morning make yourself a piece of toast, butter it and spread on your homemade blackberry jam!


Lolo’s Dad