How to Grow Walnuts



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Time to germination: 5 months to a year
Time to harvest: 10 years
Light requirements: Full sun
Soil: Fertile, not sandy

Introduction

In North America, the most well-known type of walnut tree is definitely the Black Walnut. There are also White Walnuts, English Walnuts, Heartnut Walnuts and Cannonball Walnuts.

All types of walnuts are quite hardy, and actually require a cold winter in order to thrive. So anyone living in warm climates won’t have much success with their own walnut trees. Walnuts will start to produce nuts at around 10 years of age, give full production at 30 and keep on producing for more than 50 years. Depending on the specific type of tree, they can grow up to 100 feet in height.

Many gardeners consider walnuts to be very “messy” trees, much like pecans. They drop their leaves all through the summer, and will kill nearby plants (more on that below).

Starting Your Tree

If you choose to start your walnut tree from a seed, you will want to either plant your seeds where you want your final tree, or transplant it while very small. Walnuts do not do well at all in containers because of deep tap roots and don’t handle transplanting.

You cannot just pick a walnut from the supermarket and plant it in the ground to start your own walnut tree. Nuts intended for eating will not sprout. Contact your local nursery for untreated walnuts for planting. You can plant with or without the husk still on, though taking the husk off will help the plant germinate.

Plant your nuts in the fall, and protect them from squirrels. They need a period of cold before they will sprout. It only needs to be about 3 inches under the soil. They should sprout in 4 to 5 months, or possibly not until the following year.

You can also buy small seedlings, or larger grafted saplings to get a bigger head-start on your nut crops. Grafted saplings have walnut tree branches grafted to the trunk and roots of another type of tree (which is why the survive transplanting better).

One tree is fine on its own, but if you want a group or stand of walnut trees, you need to keep 20 feet or more between them. A single walnut tree can self-fertilize, meaning you will get nuts even with just one tree. You can get a larger harvest of nuts per tree if you have 2 or more though.

Placement of your tree is more important than with most other nut trees because walnut leaves are toxic. The leaves (as well as the roots) give off a substance called juglone, and it will kill any other plants nearby including the grass. So if your plans include having your nut trees within the yard, or overhanging other plants, you’ll have to pick another kind of tree. Also, keep your walnut leaves out of the compost pile.

Unlike annual garden plants, your walnut tree is a more permanent installation. It’s important to take the necessary time to map out the best location for your trees. There should be full sun (remember to plan ahead by at least 10 years), and no solid rock at least 3 under the surface of the soil. Ideally, your soil will be rich and well-drained but not sandy.

Tree Care

Depending on the age and size of the tree, you may not be able to significantly treat diseases or insect infestations on a walnut tree.

Webworms or tent caterpillars can be a problem if there are too many of them on your trees. They build large tents of webbing, that can house hundreds of hungry caterpillars. Cut any branches off with tents and dispose of them carefully. If the problem is severe, spray the tree with BT (Bacillus thuringinsis) a natural bacteria-based pesticide that will attack the caterpillars. Harsher sprays of Carbaryl or Malathion can also kill them.

Full size trees have very long and deep root systems, which usually can protect them from moisture problems on the surface. But after very prolonged periods of drought, your trees might need some watering. You can end up with “burned” walnuts come harvest time if you let your trees get too dry for too long.

Walnut trees should be left to grow naturally without pruning.

Harvest and Storage

If you didn’t already know that early black dye came from Black walnut husks, you’re going to learn after you try to harvest a few of your nuts.

Initially, your tree will produce round green “fruits” that look quite a bit like tennis balls. These are the walnuts. The green outside husk actually has the nut inside of it. To harvest, you have to wait until they are mature enough to drop off of the tree on their own. You don’t pick them. This can make for a bit of a messy and unpredictable nut harvest.

As they ripen, the green husks will come apart and turn black. It’s at this point that they will stain anything they touch, including your hands. Don’t leave your nuts for too long inside the husks at this point. The oils will seep in through the nut shell, and taint the nut meats. Get the nuts out of their husks as soon as they drop off the tree.

Getting the husks off can be a bit of a chore, and some home gardeners even lay out their nuts out on the driveway and drive over them. There are less drastic measures though. Rolling them back and forth on a hard surface (driveway, sidewalk, large stones), with your foot is a more common method. You’ll need to put your weight behind it though. The nuts and husks will stain your work area, so don’t unhusk your walnuts out on the front sidewalk.

If your nuts have ripened enough to be very black on the outside, you may find worms have made a home in them. These are husk fly larvae and they make husking a bit unpleasant but they don’t represent any danger to the hard nuts inside.

Inside the husks, you’ll find a whole walnut in its shell. Wash off the husk remains and keep your harvest somewhere warm and well-ventilated for a few weeks. Warmer temperatures will mean a shorter drying time. You can check for adequate drying by cracking open a nut and testing the little hard divider that runs between the two halves of the nut meat (sometimes called the septum). That piece should be hard and crisp. If its soft, then your nuts aren’t dry enough. Fresher nuts won’t taste the same, though they can be eaten.

After that, you just have to shell them to remove the edible nut meats inside. Dried walnuts still in their shells will last up to a year.

9 Responses to “How to Grow Walnuts”

  1. jude austin  Says:

    I have bought walnuts in spain, up to july they were fine but now in aaaaugust I have cracked them open and they all have a worm in them plus little black specs which i gues is their waste, what can I do next year when I buy or harvest them

  2. David  Says:

    The only thing I could think of would be to freeze them. Hopefully kill off the worm before it hatches. It no doubt has to mature before any cold period and probably could not stand the cold as a larva.

  3. Shirley Billingsley  Says:

    I planted a walnut that i purchased from the store at Christmas time. In just a few days, i had a beutiful walnut tree. Of course, i gave it away, since i could not plant it in my apartment complex. They loved it.

  4. Hal  Says:

    From Victoria B C Another method of removing husks, put the green nuts into a bucket, and let them ‘ferment’. the accumulated moisture from the other nuts seems to help break down the husk, then wear gloves and strain the nuts from the blackened husks.
    mu walnuts would not survive being driven on by a car. Once dried I can often open them with bare hands, unlike supermarket walnuts.
    and yes, leave space for them to grow. Not too near the road.

  5. Chris  Says:

    Have a question. Staying in a house temporarily, and there’s a walnut tree. I picked up a couple of the “tennis balls” figuring I could plant them in a large pot till I move(unsure when, hopefully few months), then transplant at my permanent residence. Now I see that’s not good…..Is there anything I can do to preserve the nuts till I can plant them permanently? Another quick question, are these toxic to pets, dogs mainly? Guessing not since mine have already discovered them and play and chew on them, but still figured should ask if I need to be picking these things up out of their area regularly. THANK YOU :)

  6. Ann  Says:

    We livein Australia where we have a cold winter and hot summer, we have a large walnut tree which is about 15 years old, it produces a lot of nuts, but they fall off the tree when still quite green do not splitnon drying out??? They dry out and turn black but do not split of there own accord, what are we doing wrong

  7. Sally Raspin  Says:

    Dunno, but we have the same problem in southern NSW.We ended up with trays of withered black objects.

  8. Mike  Says:

    It is almost April here in Kentucky and I just located a walnut tree on our farm that has many walnuts in their dried husks on the ground. What would be the best way to remove these dried husks before allowing the walnuts to dry in their shells? I have heard of a method or burning the husks off, but can’t find any internet posting concerning it.

  9. Kay  Says:

    I have many walnut tress growing on our property; what a mess! We have always just picked them up by raking and depositing them down back for the deer to eat. I just read the above article. this is certainly a chore to get a walnut out of its husk. I wonder what procudure the big walnut companies use to get the nuts out. I surely would like to use the walnuts in baking but do not care to “tend” to the nuts over a period of time. ;(

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