How to grow black walnut trees from seed

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black walnut

Black walnut trees are highly sought after. Foragers collect their fruits from midsummer through early fall to enjoy the rich flavor of their nutmeats – if they can beat the local wildlife. They are also among the most desirable hardwoods for furniture and cabinet making. Even their hulls can be put to use to make unique wood stain.

Black walnut trees are still considered abundant throughout the Midwest; however, they are not as widely dispersed as they once were due to being harvested for lumber. Black walnut wood is desirable because of its deep color, its dimensional stability and resistance to splitting and the fact that it seldom decays in the center. It’s actually a stronger wood than white oak. A large walnut tree or a stand of trees can reap a decent pay day.

Walnut trees planted today wouldn’t become mature enough to timber for 40-60 years. So planting a grove intended for lumber would be an investment for retirement or future generations. Fortunately, you’ll be able to enjoy shade and foraging opportunities much sooner.  It only takes 10-13 years for walnuts grown from seed to bear fruit.

If you would like to plant walnut trees there are a few considerations you need to make to ensure success. Learn how to pick an ideal planting site, choose viable seeds and ensure seed germination to successfully grow a walnut tree from seed.

Choosing a location to plant walnut seeds

Walnut trees grow most abundantly along stream banks, along watercourses, in bottomlands, open fields and along the edges of forests. They prefer full sun and deep, moist, rich, well-drained soil. They will grow in soil containing clay or rock, but much slower than seeds planted in unobstructed soil. Additionally, they prefer soil with a pH of 6.0 to 6.5.

Once you find a location with ideal growing conditions, the next consideration you need to make is what else is growing nearby. Black walnut tree roots produce juglone, which can affect other plants growing in close proximity. These plants include pines, potatoes, tomatoes, blackberries, alfalfa and apples. You’ll have to find a location with ideal growing conditions where your walnut tree will not negatively impact neighboring plants.

Determining whether seeds are viable

Not all the walnut seeds you’ve collected will be viable to grow a tree. You can determine viability and how many seeds to plant per hole by following these steps:

  1. Remove husks.
  2. Place nuts in a bucket of water.
  3. Discard floating nuts.
  4. Save nuts that sank to the bottom.
  5. Crack open a small sample of the nuts you have left to determine viability. Viable nuts have white, solid meats; non-viable seeds have beige, shriveled kernels that are watery or give off a foul odor. The percentage of viable seeds in your sample will help you determine how many seeds you need to plant per hole to ensure success.
  6. Figure out how many seeds to plant per hole. If 80-100% were viable, plant 2 seeds per hole. If 60-80% were viable, plant 3 seeds per hole. If 40-60% were viable, plant 4 seeds per hole. If less than 40% were viable, plant 5+ seeds per hole.

Ensuring germination of black walnut seeds

Before walnut seeds will germinate, they have to be exposed to cold temperatures and moist conditions. This can be accomplished by planting nuts outside in the fall or by stratifying them indoors over winter.

Planting outdoors

Black walnut seeds should be planted about 2 inches deep in moist soil in the fall. If you’re planting more than one seed per hole, space them out so that unwanted seedlings will be easier to remove later.

Stratifying indoors

Stratify walnut seeds by placing them in a moist mixture of sand and peat moss and then storing them in a cool location. You can store them in the refrigerator in plastic containers or food storage bags. The stratification process takes 90 to 120 days. Check periodically to make sure your seeds have not dried out.

After they’ve been stratified, they can be removed from the refrigerator and planted in the spring.

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45 COMMENTS

    • Carol,

      You can remove the husks when they are green or black, but it’s much easier to remove them when they are black and dried out. I would also recommend using gloves to remove the husks because the juglone in walnut husks will bind to your skin and turn your hands black. It takes a long time for it to finally fade and be washed away.

      • I can attest to the discolored fingers if gloves aren’t used! Started removing husks bare-handed and saw the stain beginning to appear on my hands after husking a few. Fast Orange to the rescue. Husked the remainder wearing surgical gloves.
        I read this article after collecting a backpack-ful of black walnuts first week of Nov 2023. Thanks, Sara, for the helpful guidance. I husked 100+, placed in a pale of H2O to test for viability, and placed viable nuts (the sinkers) in individual pots covered with ~2” of soil. I am going to leave them outdoors over winter 2023-24 (I’m in Wayne County, PA). Doing same process with butternuts I harvested from trees on my property. I’ll make a note to circle back to this page in Spring ‘24 to report results and share any insights I may learn.
        Good luck, growers. And thanks again, Sara, for your helpful piece.

  1. If starting the seeds in a container, what size container should be used? Also, is it advisable to permit the container grown trees to get to say 2 ft high before transplanting into the ground? Should this be done in spring or fall?

    • You can start walnuts in containers that are about 20 inches wide and 18 inches deep. You should transplant the small walnut trees when they are about 1 foot high. Early spring is the best time to transplant.

    • Penny,

      You could try mechanical barriers to keep them out. I found this information from the USDA Forest Service Northern Research Station — https://www.nrs.fs.fed.us/pubs/wn/wn_5_06.pdf. Or, you might also try putting peppermint oil on/around the seeds because most animals that dig them up find them by smell and are deterred by peppermint oil. I hope that helps and good luck!

      • i have a 2 ft-16 ft long path of mint plants and my squirrels run and play in the mint and they dig up all the time the mint and garlic and horse radish i have growing roots are not out of there reach of destruction but i have city tree rats and they have destroyed a lot of my hebel plants i planted this year and yes i have seen them doing it on my cameras this is how i know what is destroying all my hard work

    • There’s a possibility some of them could still sprout, but, depending on your location, they should have emerged by now. I’m not sure how deep they were planted, but another thing that could be affecting them is leaving the husks on. Ideally, they would be removed and you would test the viability of the nuts using a bucket of water before planting them.

    • It’s only really necessary to use it until your trees become established. I would say through the first growing season would probably be enough.

  2. Thank for the information. Question? Can I let the nut dry first & then put them in the refrigerator? I have taken the husks off & hung them in the house in onion sacks to dry.

  3. Can U answer a question
    I have cleaned nuts have them soaking today
    tonight will be 24 hours soaking
    I am Putting them in plastic bag with peat moss to
    stratifying them
    Can this be done in my fridge where I keep my food also
    I am putting them in zip lock bags

    • Helen, you can stratify them in your fridge as long as the temperature stays between 32-40 F. It will take 90-120 days to complete this process.

      • I have a tiny its maybe 2 inches high, i carfully took it out of the ground it was in, kept it moist till i got home and put it in my Gerber Daisy potted plants, now what do i do to keep it alive? Will it winter ok with the Daisy”s in basement till spring?
        Thank you,
        Lisa Marie

  4. Have a (only one) 2 inch sapling, carefully removed from soil it was in, kept roots moist till i got home, put in my gerber daisey potted plants, will it winter ok with them in basement till spring? Northern Wisconsin frost will be here soon.

    Thank you,
    Lisa Marie

    • Robbi, Stratify them indoors to make sure the seeds get cold enough to germinate. When you plant them outdoors, do your best to find a moist location with well-drained soil.

  5. I threw some black walnut seeds into a zip lock bag that I had put ground in and a bit of water. It was placed in the bottom drawer of our basement fridge and left from Oct/21 until June/22 when I remembered to check the bags. To my surprise I had 20 some shoots up. I carefully transplanted in to peat pots and have them in my garage at the moment. So I have approx. 20 , 1” high black walnut trees . It is Almost December what do I do with them now?? Should I just leave in the unheated garage and transplant in spring? Do I water throughout winter? Do I put them in total darkness or leave near the only window in garage (west window)

    • Debbie, I would leave them in the garage to transplant in the spring. Make sure the soil stays moist, only watering them when it feels dry, and put them near the west window.

  6. After 4 months of cold stratifying I saw nothing. I then went and got a knife and gently cracked the shell all around to allow for the root to more easily sprout. I then went and put it in peat moss and would pull the walnut every day for signs of rooting. It took exactly 5 days for me to see the root start to bulge. For the remainder of the walnuts, I got my carpentry chisel with my 300g hammer and gently tapped the rest of the walnuts until I heard a change in noise, indicating that I had cracked the hard shell. Hope this helps anyone that cares or reads this.

  7. I planted 18 nuts in separate containers, but did not plant them on their side. It’s been about 2 months & nothing yet. The squirrels managed to dig out a few. I still have a few more to plant. Any advice?

    • You may not be seeing any growth yet because walnut seeds have to be stratified in cold temperatures before they will germinate. The stratification process takes 90 to 120 days. If they don’t grow this year there’s still a chance they will next year.

  8. Hello Sara! This is a beautiful article and thank you for your individual help for so many walnut planters. I am wondering how long seeds can be stored if kept cool, dark, and dry? I want to give them as a gift…

    • Henry,
      I believe walnut seeds can stay viable, if stored correctly, for several years. When in doubt, you can always soak them in a bucket of water and get rid of any that float.

  9. Hi Sara, great article!

    Would you recommend planting the germinated nut after the last frost or simply in the Spring period? I am up in ONtario

  10. After cracking the Walnut to see the white viable nut, can it still be planted and grow? Can the nut be planted when the weather is warm after it has been literally Frozen all winter long? I live in Utah and I’ve only got two seeds to sprout. Last year when I tried it said to keep him in sunny area and I only had one sprout and put it out in the sun which cooked it to a crisp.

  11. Please advise if I can still get a walnut tree from these nuts? I took off the green and black husks from the walnut, soaked them for 24 hours and then cracked one end open a bit. Can I still cold stratify them in peat moss in my fridge? I was going to germinate them in paper towel but I’m in Ontario and it’s too late to plant them outside. I changed my mind mid-stream – but I think I ruined the nuts for stratification?

    • You should still be able to stratify them indoors as long as they are not already sprouted. If you get sprouts, you can grow them indoors and plant them outside in the spring.

      • How late can I plant? I’m in NE Oklahoma and it’s Dec. 9th! Is it too late to plant them in the ground outside or do I need to stratify inside? Thank you for all your help!

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