Wild Blackberry Jam

Every August, I’m faced with the tough choice between how much I adore the taste of wild blackberries and how much I hate picking them.  It’s 102 degrees outside, the sun is blazing, picking blackberries almost invariable involves a hike, and, best of all, they’re covered with thorns.  As much as I love California, I still daydream about the soft, dew-covered grass back in New York that you can walk on barefoot all summer long.  The plants on our property here are either pointy (star-thistle, nettles, blackberries, etc.) or make you itchy (poison oak).

Ah, but the blackberries.

Their flavor is rich and dark and perfect for jam. Varying degrees of sweetness from the wild berries makes a complex final product with plenty of sweet and plenty of tart; the berries that make your mouth pucker when you eat them raw are the magic ingredient here.

Of course, make sure that whatever berry patch you find hasn’t been polluted by run-off from a nearby road or sprayed with anything (which is good practice for foraging in general).

The actual making of the blackberry jam is easy as pie.

Wild Blackberry Jam

Since foraging tends to involve inexact amounts of produce (unlike the pretty baskets of berries at the farmers market), this recipe works better written out as a formula.

Yields: every cup of crushed berries that you have will end up equalling about one half-pint jar of jam.

Cook Time: about 30 minutes, but the time will vary drastically according to how many berries you cook in a batch


  • wild blackberries:  I recommend a batch size of 4 c. of prepared berries.  Much less and you will have to really be vigilant to prevent sticking and burning during cooking. Too many berries and you will end up cooking the jam so long that you may lose some of the fresh blackberry flavor. If you go nuts and pick 12 cups of berries, just split them into four separate batches. The amount doesn’t have to be exact, though. No need to get four cups on the nose. 5 and 2/3 c. would work, or 3 cups, or… you see where I’m going here.
  • sugar: equal amount of sugar to crushed berries

1. Bring boiling water canner to a boil. Wash jars and lids in hot soapy water. 

2. Rinse berries and drain thoroughly. Put the berries into a mixing bowl and give them a gently crush.  Not enough to completely pulverize them, though; some chunks of fruit in our jam is a good thing.

3. In a large, non-reactive pot, combine the berries with an equal amount of sugar. If you have 4 cups of berries, put in 4 cups of sugar. 1:1 ratio. Easy. 

4. Cook the jam until it reaches 220 degrees on a candy thermometer (or whatever gel test you like to use). Stir occasionally to prevent sticking. Remove the pot from the heat and ladle hot jam into hot jars, leaving 1/4″ head space. Wipe rims clean and screw on lids. Process for 10 minutes in a boiling water canner. Now hide those jars away, deep in the pantry where no one can find them.  Once people know how good they are, poof! They will be gone. This photo and one lone jar is all I have left from my blackberry picking mission. (My brother discovered the jam and realized that it will make the best peanut butter and jam sandwich you’ve ever eaten.)

The vibrant flavors in these jars taste like August, and remind me of the rows of wild blackberry jam that my mom had on the pantry shelves when we were little kids.

Maybe you’re weary and you don’t give a damn

I bet you’ve never tasted her blackberry jam

-Greg Brown, from Canned Goods

18 thoughts on “Wild Blackberry Jam

  1. Ahh another blackberry lover. Blackberry anything tastes divine in the dredges of winter.

    Question – does the jam need any lemon/acid or is it already in the berries?

    1. sally, I didn’t put lemon juice in because the wild blackberries have plenty of tartness to make the jam taste really good. When I use farm blackberries, I always add lemon juice. (as far as canning safety goes- In the big Ball Book of Home Preserving, their basic recipe for no-pectin blackberry jam is just berries and sugar- no lemon juice- so my thought process was that if it’s in the Ball cookbook, I could also omit lemon juice. there’s more sugar in their recipe, but I don’t think it changes anything).

  2. Even with the soft cool grass under my feet as I pick the blackberries… oh and those wonderful mosquitoes…they still grab my clothing, let go let go, then grab my skin, ouch which way do I turn…but so worth the trouble.

  3. Im going to be doing this. I went berry picking on a friends farm. I think I picked about 5lbs of berries and this is just the first round. Everybody is already asking for jam lol .

  4. I always put some lemon juice in my blackberry jam… this year I was out of lemon juice and didn’t realize it. In a pinch I used some Key Lime juice I had left from Key Lime pie this summer. Oh man!! What a great flavor. Just a hint of lime, but you could definitely tell it was there. I had to label them Blackberry-Lime Jam so I’d remember to use the lime next year!

    1. nancy, that’s a great idea! you know, i bet grapefruit juice would be really could too. it’s a whole new world of citrus combinations… dang, I need more blackberries now

  5. Your jam is GORGOUS!! I’m going to attempt my first batch of blackberry jam in a few weeks & need some help. My thornless bberry bush produces beautiful, tender, but TART berries – there is no sweetness to them until the berry is about to fall off the stem!
    So Question #1 – should I add more sugar than is called for in the recipe? I don’t want it too sweet, but not so tart you don’t want it on a PB & J.
    Question #2 – any suggestions about how to make this SEEDLESS? I’ve got a persnickety husband I’m trying to please. I don’t want jelly – I like the bits of fruit, but just want no seeds.
    Thanks!! And thanks for your blog – I’m addicted!!

    1. It looks like beti answered your question above about the seeds, and as far as the sugar goes, I would leave it just the way it is. 1:1 fruit sugar is a fairly traditional ratio for jams, and I think you’ll see it’s plenty sweet to please everyone. (but not gross sweet, like the recipe in the powdered pectin package). And thanks for your compliment, i’m glad you like it!

  6. Excellent – thank you! I’m on five acres and almost all five of them are covered in blackberries. I’ve been picking about five cups a day (I could get more but, really, five is more than enough). I should get off my tail and get to canning.

  7. Mmm, your blackberries look delicious. What a great idea to put lime in with it, too. I have also been picking blackberries this year — gobs and gobs of them. I just made a wonderful batch of chocolate-blackberry sauce (from the Ball book — only they used raspberries). It was to die for. 🙂

  8. Thank you Caroline, I am very happy to hear lemon juice isn’t needed. The purer the blackberry flavor, the better.

  9. @T5winMom – You can put the berries through a food mill with the a fine disc. It probably won’t get out all the seeds but it will remove quite a bit and also leave you with a fair amount of pulp.

  10. My first attempt, 28 May 2012, at making your Blackberry preserves resulted in my under-cooking the berries and now I have 3 pints of runny preserves. As the jars are sealed, only one day old and having no additives, is it possible to re-cook to get the right consistency?

  11. The good Lord above has blessed us with a huge blackberry patch that just mysteriously appeared.
    We are picking about 5 quarts a day, and they have just started to ripen.
    I made the Ball Blue Book recipe yesterday. It uses 9 cups of crushed berries and 6 cups of sugar. Turned out perfect! Not too sweet, not too tart. Just right.
    Thanks for the great idea of using a candy thermometer. I am sure that will make things much easier. This is my first visit to your blog, via Pinterest. Very, very nice!
    Thank you.

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