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I'm in Zone 6a, and I'd like to plant some English Walnut trees (not Black Walnut!), but have rather clay-ish soil. Also, the area where they'd need to be planted tends to get about an inch or two of standing water for about four days after heavy rains.

In reading about English Walnuts, I see two things particularly mentioned about English Walnuts is they don't like clay soil and don't like standing water.

My intention then, would be to dig a foot deep into the ground, fill it in with better soil, and raise up a small earth mound 2 feet tall of the better soil, and plant the tree on that.

(I'm thinking of a 3x4' mound a foot deep and 2' high, structured with logs for hugelkulture and planted with grass and shrubs to reduce irrigation)

The walnut's roots will rapidly expand beyond the good soil of my earth mound down and out into the surrounding clay-ish soil; however, the tree itself would be raised up off the ground by 18" or more. Would that greatly increase the walnut's chance of survival, or would this become a losing battle for me?

Note: Despite the soil in that area being clay-ish, it's not so clayish that other trees (native and planted) haven't thrived. But it sounds like English Walnuts are particularly sensitive?

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In my hilly area there's clay or heavy clay soil and English walnuts (Juglans regia) grow well. People who've got large orchards amend their soil, but people with one or two trees in their backyard don't do anything, not even fertilizing, so I wouldn't worry too much about planting yours in clay soil.

What I'd worry about is drainage because I have seen walnuts planted in plain areas with loam soil and they didn't survive in backyards with standing water.

If the hole you are preparing drains fast, it's ok, but after the tree puts new roots outside it, you risk losing the tree. Planting it a bit above the soil line won't help on the long run because this tree sends deep roots. On the short term, strong winds might pull the tree out of its planting site.

So I suggest you create an area with good drainage and then plant it there.

To answer your comment: Both the roots and the trunk are vulnerable to standing water. The water table should be at least 4 m deep for an optimum growth, but when the tree is young it will tolerate a 3 m deep one. I have heard of nurseries selling walnuts that are supposed to bear fruit after 5 years, but I don't know if this claim is real, so if yours will bear fruit at least after 7 years you have to provide a deep water table until then. I don't think elevating it is a solution. Try to loosen the soil with a fork in your yard if deep tilling is not an option, at least until you manage to solve the drainage issue in your yard.

  • Thanks for the info about the clay soil! Due to the size of Walnut trees, I don't have much flexibility with positioning them, alas. =( – Jamin Grey Jan 23 '18 at 6:31
  • Walnut trees can send their taproots pretty deep it seems, so no matter where I plant it, some roots will eventually be below the water table. What part of the tree is vulnerable to flooding? How high do you think I'd need to elevate it to help it survive? It may be that I just can't have walnuts due to the circumstances, but if a reasonable solution emerges, I'm willing to try and risk losing them. – Jamin Grey Jan 23 '18 at 6:36
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    Please see my updated answer. – Alina Jan 23 '18 at 8:40
  • Sounds like the area I was considering just won't work for it. Thank you for saving me work that wouldn't have born fruit. – Jamin Grey Jan 23 '18 at 16:12
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    If there's a bit of a slope, then you have a chance to grow it. The artificial mound will shrink/compact over time and get closer to the ground, in comparison with a natural occuring or an old one which will pretty much hold its shape. – Alina Jan 23 '18 at 20:49
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Jamin, I support you in your determination to welcome Juglans regia in your yard, however, I believe you would be better off, in this case, doing much less work.

It is a large tree, and, eventually, a vast majority of its roots will be in the ground that you did not change. The success of the tree will depend on microclimate, and existing soil, and these you can't change.

If you change 3x3x3 feet soil environment around the new tree, you risk that roots would tend to stay in that area! The net result is a much smaller, less developed tree!

So, I would advise you to plant it just as a regular tree.


If you are really in the mood of doing something extra, do some drainage improvement in that area of the yard, so that it is easier for young walnut to establish, and for you to move. But, again, in the long term, it won't make almost any difference - the walnut is a giant.

Another thing that might be useful is to tile the whole area. I suspect the soil is very compacted. That would help to get rid of extra water after rain.

Few inches of water several days after heavy rain is not a flood - just a normal state for compacted clay area.

Also, the main source of water for an adult walnut is deep under ground - and you can't affect that.

  • I was hoping to plant three of them, but I guess I could try just planting one and waiting three years to see how it does. I'd hate to turn 7 years before fruiting into 10 years before fruiting though! Some other trees are surviving: plum, almond, apple - though apple can tolerate quite a bit more water than walnuts, and they haven't born fruit yet (this year is supposed to be the first), so maybe their roots just haven't gone deep enough for water to be problem yet. – Jamin Grey Jan 23 '18 at 16:28
  • I planted Sophora japonica, and I have to wait 30-3=27 years until flowering, let alone fruiting (and I planted it to attract polinators with its flowers). What should I say? And Pinus pinea, just 15 or 20 years for cones to appear, and then 3 more years for them to mature on the tree... :) @JaminGrey – VividD Jan 23 '18 at 16:38
  • Lol, I guess we plant for decades ahead rather than mere years. If I planted a single test walnut, how long should I wait for it to survive before I decide if it was a success and plant more? – Jamin Grey Jan 23 '18 at 16:45
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    IMHO, after two years you will have a clear hint if it was a success, and the third year will give you a definitive answer - the spring growth should be strong by then, much stronger than in any plum or apple (and roots should definitely surpass 3 feet). @JaminGrey – VividD Jan 23 '18 at 16:53
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Jamin, yes you can grow trees in berms. 94% of all plant roots get their chemistry and water from the top 6". Deeper roots are for support, not for sustenance.

Your berm needs to be compacted get the large pockets of air removed before planting your trees. Depending on your zone, you should also insert 3 OR 4" PVC pipe drilled with holes near the root ball for best watering. Fill the pipes with water during the first year of The berm itself will provide plenty of drainage to not allow roots to rot.

Remove the burlap off your balled and burlapped root balls of trees. Is your tree from the nursery in a pot or balled and burlapped...or heavens, bare root? Keep the line between trunk and roots above the surface of soil! Do not amend the soil. Do not dig any deeper than the depth of the rootball. Keep the subsoil below the root ball undisturbed. Chose a spot with plenty of room for this tree...walnut. Big deal about the difference between English and Black walnut?!

Do not plan on planting anything near this walnut. Trust me. A walnut tree is to die for! Those that know walnut, Juglans, are very careful just using walnut wood in a shop. A raised plant bed is perfect. That means double digging and raising the plant bed using just the soil you are double digging.

Please do not do hugelkulture. Ugh. Where do these fads come from? Not at all scientific. Raising the soil, just by double digging is all you should do if you are worried about drainage. NO amending the soil. NO foo foo beneath the soil. Hugelkulture is a perfect example of making a perched water table.

If you've got major drainage problems, it would be nice to see the site where you want to plant. The best things for trees is to plant them right into the spot with no amendments whatsoever. Most trees are grown in clay in the nurseries. They B & B them with a clay root ball.

Clay is wonderful soil!! Just need to know management practices! Trees grown in clay should be planted in clay! If you plant a clay root ball in a sandy or easily draining soil, your tree might die from lack of water. Water will run around the clay and down into the sandy soil. Very bad.

Do not amend your soil. Do not dig deeper than the depth of the root ball. Water regularly until established. Add a balanced fertilizer. There is no other alternative for ensuring proper chemistry for a plant. Decomposed compost is not fertilizer, is not to be used for soil. Should not be used in potted plants. Should never be used to 'amend' soil.

Compost installed on top of the garden soil is necessary to feed the soil. It has to be decomposed, dump on top of soil, never allowing the trunk's bark to be covered with soil, or mulch, or rocks...and that compost is taken into the soil profile by a healthy soil macro and micro life. Decomposed organic matter feeds the soil organisms. So very important. You have to know what your compost is made from, how far it is in the decomposition process to be able to discern the proper balanced fertilizer you need to add.

Not at the very beginning, later, in the new growth season following the planting of your plants.

Edit: 95% of all roots...are within 4 to 6 inches from the surface of the soil. The reason is water and chemistry necessary to absorb via roots for photosynthesis. Organic matter after it is decomposed can offer some minuscule chemistry (I will not say 'nutrients', replace chemistry with 'nutrients' might help make more sense...not nutrients, not food but chemistry).

A soil within a stable ecosystem has just enough life that is fed by just enough decomposed organic matter falling from this established ecosystem to be recycled to allow one new plant into the ecosystem or allow another plant citizen in the system to fight off an insect problem. Very finely tuned. We humans will never be able to mimic an ecosystem. We do have to understand our artificial gardens, especially the edible gardens.

We need to understand plant's needs; draining soil (all soil is wonderful just each type needs its own management techniques), proper watering, an alive soil which is where decomposed organic matter is critical, light, the correct amount not just any light will work, and dog gone it, soil doesn't come with fertilizer.

Walnuts, have a poison that poisonous to walnut trees... is primarily to stop their own progeny from competing with mommy/daddy. There are other plants are sensitive to it other than Juglans the genus. Usually those same plants are also needing lots of light and shouldn't have been planted beneath a Walnut tree. It truly is no big deal. Walnuts shade their root systems, keep other baby walnuts from competing for chemistry (nutrients) and keep other plants from competing because of their deep shade.

I had a Juglans full grown, once. What a wonderful wonderful tree to raise and know. Worth planting at least 3 of them, far apart from one another so that you will get at least one mature walnut tree. Better harvest in terms of calories and 'nutrients' than an apple.

I am assuming you will be purchasing nursery stock? Potted trees to 5' or Balled and Burlapped up 15'? A berm would be your best bet. When you make a raised by by 'fluffing' up the soil (it becomes huge when you start double digging), provide trenches to gather excess water and tell the water where to go, even if standing water were all around the base and the young tree had its roots in that berm out of the standing water, that tree, that plant will do just fine.

Tree roots, all plant roots, all of the 'feeder' roots are found within 4 to 6 inches of the surface.

Most trees from nurseries are grown in clay soil. That keeps their roots more confined so when they get dug up they keep most of the root system allowing for better survivability. Do not 'amend' the soil when planting trees. That berm will keep their roots from drowning. Hopefully we can help you improve your drainage. Make sure to not plant your baby trees too deeply. Only the root ball gets buried. No part of the trunk should have any soil, mulch, paper, nada touching the bark.

Send pictures, please. Tap roots are for support, not water or chemistry. There are a few trees that have tap roots that take up water and chemistry and that grow a mile beyond the canopy or down into the earth. That is a specialty. Not happening with walnuts.

Another misconception is root depth. Roots will grow wherever the environment is favorable. They require water, oxygen, minerals, support, and warmth. These requirements are usually found in the upper few feet of soil. Roots rarely grow below four feet although there are numerous cases stating the opposite. The major portion of a tree's root system is in the top few inches of soil. This makes it easier to understand why trees can be easily uplifted during wind storms or other soil disturbances.

differences between types of roots

  • Hugelkulture should only really be used in situations of high returns in vegetative material not in planting trees- plus the soil levels change radically with this practice, and decaying material used in this method can inhibit vegetative growth massively. Not recommended in permanent plantings. Walnuts also poison the ground somewhat with their decaying leaves so often you won't find much that will grow under a walnut tree. And the canopy can shade out quite a lot of sun too. Oh it takes 20 years to go from seed to fruit averagely. – olantigh Jan 27 '18 at 14:34
  • @olantigh Gosh, could you tell me in your opinion what IS beneficial with hugelkulture? I am sorry. I just do not see a single good thing from hugelkulture...sort of composting below the plant bed rationalizing the decomposition makes warmer soil? Better germination? The slopes are in no way water wise. Having water in the rotting crap? Anaerobic decomposition? So much work for what benefit? Juglone is meant to reduce competition in the walnut's world. Tomatoes, heck no plant should be planted under a dark canopy. Common sense. Walnuts are great trees. Careful working with the wood – stormy Jan 28 '18 at 5:03

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