How to Harvest Acorns: Identify the Good, the Bad and the Ugly

Once the acorns fall, it’s easy to gather large quantities. But it’s worth the time to select only the good acorns. Thanks to Sam Thayer, here are a few things to look for when gathering acorns for your pantry.

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The acorn is likely insect infested and therefore no good if:

1. the cap is attached.

2. there is a hole in the shell.

3. the shell is split or torn.

4. the top or “disk” of the acorn is shriveled.

5. the top or “disk of the acorn is separated from the shell.

6. the shell is bruised or discolored.

7. there is a dark spot on the shell.

8. there is a dark spot on the nut when the shell is opened.

Take a look at the following photos and see if you can pick out which ones are worth picking up.

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    1. Blake K. October 22, 2008 at 4:47 PM #

      #1, is that “1. the cap is attached.” or “1. the cap is NOT attached.”? I really want to know how to pick out acorns! :) Great article, thanks.

    2. jj_murphy October 22, 2008 at 4:58 PM #

      Thanks for your feedback, Blake.

      When a ripe acorn lands on the ground, the impact will knock cap off.

      If the cap is stuck to the acorn, it is immature. The tree will purge any immature acorn that is insect infested. Acorns are seeds, hence future oak trees. A diseased or infected acorn will not grow into a healthy tree.

      I hope that answers your question.

    3. Blake K. October 22, 2008 at 5:53 PM #

      Aha, it now becomes clear. Terrific information, thanks again. I’ll have to take a closer look next time I hike up the hill.

    4. jj_murphy October 22, 2008 at 6:53 PM #

      I hope the oak trees in your area are abundant this season.

      If you collect a large quantity, make sure to dry them on racks or cookie sheets near (but not on) a wood stove or in a dry room.

      Freezing them is also a good way to keep them from spoiling or sprouting.

    5. Elaine Heffernan September 26, 2009 at 6:48 AM #

      Your response to Blake K. is so interesting to me: that the tree desmonstrates such intelligence is remarkable.

      Thank you for helping make “the world be to us an open book and every form significant of its hidden life and final cause” Emerson.

      I went out yesterday really looking at the acorns that were literally raining down on my head and Lo! I found an enormous, three-headed Hen-of the-woods” at the base of a gigantic oak. So you get a double thanks, JJ!

    6. JJ Murphy
      JJ Murphy September 26, 2009 at 7:26 AM #

      I’m so glad you found this article valuable, Elaine. Check out my recipe for acorn burgers.

      You can freeze that hen-of-the-woods mushroom without cooking it and have it to enjoy and/or share for a long time.

    7. barb October 5, 2010 at 9:44 PM #

      Tips #1 and #5 seem contradictory, please clarify.

    8. jj_murphy October 6, 2010 at 4:58 AM #

      Barb, the cap is the little “hat” that sits on the acorn, as opposed to the top of the nut itself. You can remove the cap, but the top of the nut has a button-like disc which should be firm and not squishy or pushed away from the nut.

      I hope that helps.

    9. Steve Hill January 31, 2011 at 1:27 PM #

      There is a very simple way to identify good acorns from bad. Fill a bucket with water and drop your acorns in it. The good ones sink to the bottom and the bad ones float.

    10. JJ Murphy January 31, 2011 at 4:18 PM #

      Steve, you are absolutely right.

      But as I get older and more arthritic, I tend to sort acorns in the field, so I don’t have to carry the bad ones home.

      Of course the most productive trees are never the ones in my yard. :)

      Happy Foraging.

    11. David the Security Glass Expert April 17, 2011 at 5:55 PM #

      I found a site today that said it was okay to harvest acorns in the spring. What I found, using Steve’s tip, was that about 1/2 of the acorns were no good. Still, I’m in the process of boiling the ones I did get. Using Peterson’s Field Guide to Edible Wild Plants, I tried to identify the white oak acorns. According to the book, their cups are no more than 1/3 of the height of the acorn. Most of these floated when I put them in water. I also tasted a small bite of the raw acorns (both white and pin oaks, I think) and found them both to be bitter.

      Thanks a lot for educating us on how to gather and prepare the acorns. I’m hoping they work out better than the day lily shoots I foraged for a couple of weeks ago. They were delicious, but I think I needed to curb my enthusiasm, as they gave me the runs pretty bad.

    12. JJ Murphy April 17, 2011 at 11:59 PM #

      David, thanks for visiting my site and taking the time to comment.

      Yes – day lily buds and flowers have a strong “cleansing” effect. It’s a good idea to test for edibility when consuming a new wild edible.

      As for the acorns, it’s important to learn to recognize the bark, branches, tips and leaves of the white and red oaks that grow in your area. Acorns typically mature during the autumn. Any acorns you find in the spring have been sitting on the ground for several months. Some may have sprouted, many will be infested and it’s always better to gather wild edibles as soon as they mature.

      As for size – a great deal depends upon the weather patterns in any given year. For example, in 2009, hickory nuts were abundant, but acorns were scarce. In 2010 the chestnut oak acorns were abundant and much larger than in previous years, but I found very few walnuts and virtually no hickory nuts.

    13. Fernando July 6, 2011 at 3:09 PM #

      JJ, thank you for your wonderful site and advice. I have a question that I hope you can answer. i recently moved to Switzerland, and among some pear trees, apple trees and a quince tree I found what I thought was some sort of oak. But for the life of me I cannot identify it, and have no idea if the acorns are edible (or acorns at all).


      The acorns are still very green, and smell slightly sweet, very fruity and green with a very warty barb.

      Any ideas ?

      Thank you !!!

    14. JJ Murphy July 6, 2011 at 6:54 PM #

      Fernando, thanks for visiting my site and for your kind comments. It has been years since I visited Switzerland, so I don’t even know anyone to ask.

      What may aid you in your identification is to see if there is a university or botanical gardens near where you live. The faculty and resident experts may be able to help you.

      While some species can adapt to any environment, others require certain conditions to thrive.

      When you find out, please let me know what you learn.

    15. Fernando July 7, 2011 at 1:50 PM #

      Thank you, JJ. I will probably ask my neighbors when I SEE them, as the trees (I missed to write) are in my back yard. The combination of trees in my new back yard doesn’t give me time to miss anything: cherries (which we already ate, before the birds got to them), now apples are almost ready, and the pears will be ready after them. I hope by then the acorns and quinces will be ready for the table ! I will let you know if it’s some sort of local oak that we don’t see in America.

    16. JJ Murphy July 7, 2011 at 9:53 PM #

      Thanks, Fernando. Your current back yard sounds divine. What led you to live in Switzerland? Where did you live before that? I don’t know what kind of work you do, but whatever it is, I’m glad you have time to forage.

      Enjoy your new home and keep me posted.


    17. Fernando July 17, 2011 at 9:03 AM #

      Before here we lived in Southern California, and before that in South America. We travel quite a bit, but Switzerland is home. Fortunately, although I work in a manufacturing firm, we do have plenty of time to enjoy nature, which is plentiful around here.

    18. Matt Phillips September 7, 2011 at 10:55 PM #

      Fernando, if you’re still checking out this site, the leaf & “acorn” pictures (i didn’t look at the branch), look very much like the filiberts/hazelnuts here in Portland. To confirm, i would do some google searching on your own on what hazelnut tree leaves & nuts look like.


    19. tereza crump aka MyTreasuredCreations September 26, 2011 at 1:49 PM #

      hi there, just found your site researching about acorns with my children. We recently moved to a new house that has plenty of oak trees in the front yard. So the children were wondering if we could eat the acorns. They were picking them green from the trees. AFter reading your blog we found out we need to wait until they fall to the ground. My question is: Does harvesting take many days? How do we know when is time to harvest?

      thanks so much. Will keep you posted once we start harvesting.


    20. JJ Murphy September 27, 2011 at 7:25 PM #

      Tereza, I’m always delighted to hear from people who encourage their children to forage. I find that when the oak trees drop their acorns is the best time to harvest them. Some people will pick them off the trees – I’ve done that, too. Some people have gathered them the following spring, but by then the acorns have been on the ground for several months. Of course if they have been frozen, it may not matter.

      Harvesting the acorns is the easy part. Leeching the tannin out of the acorns is where the real work begins.

      As I stated in my article, you want the acorns that have no cracks or worm holes. I store the acorns I’m not using in my recipes in the freezer, which keeps them from deteriorating.

      The most effective way to leech the tannin is to remove the shells and chop them (food processors save time) and then soak them, changing the water and tasting them until the bitter flavor is gone.

      My accomplished forager friends take the time to make acorn flour – and the baked goods they make are heavenly.

      I simply use the chopped acorns in acorn burgers – just as much nutrition with a lot less work.

      Do keep me posted on the results of your experiments.

    21. John June 11, 2012 at 10:11 PM #

      When do acorns usually fall? I just moved and we have an oak tree in our backyard. The acorns haven’t grown yet so i’m just wondering. By the way, thanks for the advice on harvesting them!

    22. Mary Harrington October 26, 2012 at 4:22 PM #

      Fernando, I used to live in CH 9 years – that looks like a hazelnut aka filbert tree:

      Most pastries, cookies, cakes if they have nuts are using hazelnuts, very seldom will you see walnuts, pecans but they do use almonds too.

      I live in Southern California now and there are native hazelnut trees here too, I’m planting one in my yard.


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      [...] According to Sam Thayer,this is what to look for to ensure that acorns aren’t infested or inedible: 1. the cap is attached (If the cap is attached, the acorn was released by the tree prematurely, most likely due to a defect of some sort.) [...]

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