Can I plant English Walnuts on earth berms above poorly draining clay soil?

Question

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?

Answer 1

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.

Answer 2

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.

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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.

Answer 3

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