planting trees in clay soil

I just discovered my entire yard is heavy clay when I dig deeper than about 6-7 inches. I already purchased 3 trees, a prairiefire crabapple, an autum blaze maple, and a corkscrew willow.

Help! I need advice on best way to plant in clay. :-(

The best way is to make a raised bed and incorporate the clay base up into the soil above. Digging holes to plant in the traditional way will cause a fish bowl of water. In my clay areas I have dug down and added lots of leaves, pine needles, bark, sticks, and compost to make the soil drain. If you dont want a raised bed make a mound to plant on mixing your clay with the above additiions.

All those trees do very well in clay. I would just plant them without a whole lot of worry or fuss.

Scott

Agree with Scott - the willow and the maple are really just big weeds anyway, and aren't particularly choosy about soil type. The crab will be just fine, so long as it's not sitting in a bathtub of wet, soggy soil amendments.

I'd just dig my holes, plunk the trees in, and backfill with the native soil. NO amendments mixed in. If you feel the need to amend, mulch with it, and let the earthworms and soil microbes deep cycle those nutrients.

Scott, I totally agree with you.

Haleysaunt, I live in clay soil and while any plant could do better with some babying, my gosh, just look around where you live and you'll see trees popping up all over in nature! So you can't go wrong, any tree for your zone should be able to grow. They always just recommend digging the hole for a tree 2x the tree root ball anyways, that would be the time to amend the soil around it by backfilling with some softer enriched dirt. Just water water water like crazy so the roots will establish themselves well.

Lucky, =( HEY! I love the willow AND the maple. But I do know the willows can be messy, we had an awesome one growing up and since we had woods with no drainage behind our house in Michigan, once the snow melted, it was a swamp and the willow LOVED it and blessed us with huge limbs from which to rope swing from, what a blessed childhood. =) Since my property isn't near as large now I am just using maples. Curious as to why you say they are just weeds? I haven't seen hardly any maples in my area here.....but open to your take on it.

Just to clarify: I don't recommned amending the planting hole. This has been carefully studied and proven to create the dreaded "bathtub effect." The bathtub effect is this: if you have clay, and if the clay drains slowly, by digging a hole and filling it with a soil different from the clay, all you've done is create a bathtub of sodden, rotting, anaerobic amendments. Not good.

In my first post I suggested that you just go ahead and plant those trees in your native soil and be done with it. Go ahead and mulch. But those trees do fine in clay and I would just leave it at that.

However, if you absolutely must amend, only amend the top four inches of the soil in a big bead surrounding the planting and be sure to mix a good amount of your native soil in that top four inches. Doing this is just expediting the formation of a decent topsoil, probably aids the tree some, makes the gardener feel like he's done something, and probably doesn't create any problems.

Scott

Thank you for the info, support and advice!

I am going with the "no amendment" planting technique, and let Mother Nature do her thing.

I am also planting Roses in May, but I will do raised beds for them, just as I will be doing for my vegetable garden, which I need to get started on as soon as I get these tress planted. :-)

Thanks, everyone!

OK I have to jump in here and tell you when those trees reach a tremendous height, beautiful flowers, spectacular fall color, and cause you visitors to remark on their beauty you will have no responsibility in their success. You won't be able to brag unless you soil ammend. Mounds with ammendments won't hurt but then you can say you caused that beauty! LOL

Decumbent, I think you are onto something about the amendment. I have heard that doing it too much in clay soil can cause the roots to be bound up, trying to stay in the amended soil because they don't want to struggle through growing in the clay. I'd just say, amend the slightest bit with 1-2 bags of soil, but definately backfill with most of your clay. Having added the tree you've beautified the environment and we thank you!

"No, no, no!" Says the Clay savvy fellow. I can keep my mouth shut only so long.

Amending clay is absolutely the best thing you can do, but interface is what binds roots and creates the "Bathtub" effect. Local arborists here say to amend 5x the rootball width, and only as deep. The key, I say, the KEY is to break up the line between two soil types, so that it is s steady and gradual change from container mix, to the amended soil, to the native unamended. Asking the city's tree folks will say that they have better luck with planting the trees a few inches higher than the native soil level as well, and 90% of those planted too deep will die within five years. So, the most concerning thing about planting a tree in clay is the depth. Also to note is that there are no roots to gurdle the lower trunk that resulted from container culture.
I must say it again: Break the Interface.
If you want to know all of the reasons why clay benefits greatly from amendments, just prepare for an earful of science and a trainload of annecdotal evidence.

Whew. I feel much releived to get that out.
K. James

And-
Newly planted trees in clay are highly susceptable to overwatering, and for obvious reasons. I must respectfully disagree with "water water water".

Amen JamesCo also consider this when making your 3X hole. Use some laterals (wood, plastic, bark) to catch the root expantion and send it out into the transitional soil and continuing into the native. Think of it like a spoke to a wheel. We all need guidance.

Laterals? The spoke form is right, though. That will happen to any aspiring sapling in good health with proper planting.

How many saplings are root bound. Most of the ones I buy cheap at the end of the year.

I dont know if it helps but when I plant in clay soil I usually mix some oak and hickory leaves in with the soil.

A person has to remember that those roots going around and around and around and around will not straiten themselves out- they will just thicken into a wall of roots that will ultimately strangle a tree, which I'm sure you know, Steve. Oh fantasy; the ideal world would be one in which every tree is planted by seed...

Strait leaves mixed well simply add more useful organic matter. I often use leaves and coarse compost to soften cacking clay surfaces, but it is said that having uncomposted material around plant roots is a questionable practice- I can understand it, but have not had problems myself with it, (given that they cannot layer and mat) leaves certainly won't nitrogen-burn anything! (In fact, they are more likely to take Nitrogen)

Steve, what did you mean by Plastic for "laterals?" Actually training the roots to go one direction? That seems to backfire when I've read about it.
K. James

We have clay soil on the Great River Road in Montz, Louisiana. My parents and grandparents before me had beautiful gardens. It was not until I became the steward of the place that I appreciated the work that had gone into their beautiful landscapes. Digging into it is hard work and if it is at all wet, it sticks to the shovel or the hoe or the tiller. When wet it can be used as cannon balls and when dry it is like concrete.
My father always worked in leaf compost into his beds along with rotted chicken manure, cow manure and horse manure which he had readily available. I remember my mother walking about half a mile farther back to a sandy river ridge with buckets carrying sand to amend her beds.
I have planted in the pure clay and I have planted in the amended clay in the past 19 years and I find that things grow much faster and better in the amended clay. It must take roots twice as long to get through the heavy soil.
When planting smaller shrubs, such as azaleas and camellias, I only dig down about two inches and then build amended soil around the roots of what is being planted. That works well.
I was told by an arborist, when I planted several live oaks, not to amend the soil. However, I worked in compost and leaves for one of the plantings and that one live oak has passed up the others greatly.

Yes Kenton I'm talking no bigger than 2 gal root bounds they have only had 1 season with roots curling. So i just break open the bottom 1/3 of the root ball and place it on a 2x4 welded fence base with laterals wired on. I have dug up the tree and moved it and there is no ringing going on. I think you need the wire base to be effective. I have even made a volcano shaped base with laterals to train a burr oak with curled taproots. I don't plan on digging that one up.

Here is the most up-to-date information on this that I have been receiving. This information is coming from Ohio State University horticulture professors, studies by Carl Whitcomb, and others. Granted, this information is coming from academics, but it is supported by numerous field studies.

They all are emphatic that best results come from not amending planting holes for large woody plants.

No matter how large your planting hole is, or how little or how much you amend the backfill, and no matter how much you create a transition from improved soil to native soil, no matter any of that, your tree will eventually have to make it or not make it in your site's native, natural soil. Therefore, amending the planting hole represents a number of potential problems and little, if any, benefits.

The worse the native soil, the worse it is to amend!

If native soil is so bad that nothing can be planted in it, or if it is too bad to support the types of plants you want to grow, then you will need to create a raised bed consisting of the desired soil. However, unless you can create a half acre of raised bed, this will not work for most large shade trees, such as willow and red maple.

If you were so foolish as to create a 1/2 acre raised bed of decent soil for a red maple or a willow, you might consider making it of heavy clay. These trees do really well in heavy clay. But, of course, you've got heavy clay already.

I am no stranger to heavy clay. I have it too. Heavy clay is normally fairly high in minerals and holds onto nutrients well. It is not the worst soil you can have. The main concern with heavy clay is air and drainage. Air and water have a difficult time moving through clay's fine particles. Therefore, your soil will frequently be too wet, possibly too dry, and often not porous enough for oxygen to penetrate to the roots. Deep soil amendments will do nothing to fix this. Four inches of improved topsoil in as large an area as possible around the tree will help, as will 2" of mulch.

Digging the hole twice as wide as the root ball will create a decent enough transition from "dug" soil to "not dug" soil so that roots will escape the original hole. It will also loosen up the clay a bit and aid root development. Tilling 6-8" deep around the hole, again in as big a space as possible, is beneficial too.

None of the above applies to anything except trees and large shrubs. Good, large, amended, and raised beds are necessary for successful gardens of just about everything else.

Scott

This message was edited Mar 11, 2006 3:44 PM

Thanks, Scott. How is the amendment detrimental to a tree? As far as macro/micropores in clay, why would "Deep soil amendments will do nothing to fix this"?
I assumed that it would increase the oxygen and water penetration by increasing the porosity, at least aiding the tree when it is young, admitting that when the tree is mature and its root area is full-sized, that little spot is pigsqueak, and the tree's ultimate success relies completely on, as you said, the state of the native soil.

I could see it if amending the soil pampers the tree too much so that it is a ninny when time to go into the native stuff, not to introduce it into its new soil-environment as soon as possible.

And, I admit that I am just crazy enough (or foolish) to deeply amend huge areas, till and topdress larger areas.
K. James

Amen Kenton. What do you think God did when he/she was building the earth? Soil amendment. He/she did not expect anything but improvement to clay structures. IE worms, volcanic ash, pill bugs, wayword gofers, all made things different to the point that the lower mississippi valley is a garden not a patch of clay. God gave Kenton and I the desire to rise above learned scholars to make the transition of root to adjust to transitional soils. Root evolution in the short life of the plant. Look at root growth and tell me that it has no potential to change in a short generation of cell mitosis. I agree that it needs Oxygen and moisture but that root stock finds it. Follow the gofer hole, follow the gofer hole, follow the light. Hee Hee

Hi James,

How is the amendment detrimental to the tree? Well, it comes back to the fact than anytime you dig a hole in clay, and then fill it with anything except that same clay, all you've done is create a depression in the clay. The altered soil in the hole will moisten, dry out, and freeze/thaw differently than the surrounding clay does and the tree's fate is beholden to a bunch of variables.

As for the amendments aiding the tree while it is young. I'm with you on that, which is why I usually do amend the top four or so inches with some compost or manure. At a recent seminar, a Dr. from the USDA facility in Corvalis, OR spoke, and she, like you, recommended adding some compost to the backfill. (This was the first time in a long time that I had heard an academic horticulturist make this recommendation). She was immediately asked about the "bathtub effect," and her response was that the compost would be used up so fast as to not matter.

I'm not so sure. And this leads to my determination against "deep" amending. Microbiological activity is lessened with every inch of depth in the soil you go. Organic matter that would be consumed rapidly on the surface, might not break down for years two feet down. Organic matter sitting beneath a tree, two feet deep, in a weirdly draining "bathtub," could cause strange things to happen.

The other reason for not deeply amending is that 80% of all roots and virtually 100% of the important feeder roots are in the top 8" of the soil profile. Assuming that amending is beneficial, then certainly amending any deeper than 8" is reaping minimal rewards in ratio to the effort and expense to get them there.

One more reason to amend shallowly. That's where all the action is, microbially speaking. Plants do not consume compost. Plants absorb the stuff microbes make as they consume to the compost. Well over 90% of all soil life is in that top foot. Putting organic matter any deeper is essentially making it unavailable.

Sulfurdig,

Yes, God made all soil amendments. (I think it was on the fourth day). He made fallen leaves and manure and volcanic ash and and all kinds of good stuff. He knew what He was doing when He made all the Earth a garden. He also knew what He was doing when he put all the leaves and manure and volcanic ash and all the other good stuff ON TOP! You'd never catch God double-digging! Yes, you can rise above all the learned scholars by clawing into the earth on bended knee and broken back, and James.com too, but me? I'll just put the stuff on top, just like God. Maybe I'll do a little tilling, and might add some sulfur to bring the pH down a bit, and I'll mulch, and water, and take photos, and chase away deer, but my days of amending planting holes are over.

Scott

Scott you have nowhere to go for hope in a soil that is less than you want. LOL I shall always amend because all my beds are raised. No bathwater there.

I no longer amend my planting holes. To do so creates that nice bathtub effect mentioned by Scott that tree roots rot in for me in no time flat. When I dig, I set aside that which was removed and use the same material. I do mulch heavily these days and I do make sure the tree is planted 2" - 3" above grade. I am dealing with heavy clay. Since I ceased amending the hole, my mortality rate has gone down dramatically.

Dilligent:
Perhaps it is wishful thinking that macropores would be large enough to bring oxygen/microbial activity way down there, eh? All of that organic matter tends to attract worms who create some very nice air-tubes.

I hope that having an amended foundation, grown in by the tree or not, is nice to have, as worms will be moving that matter around, up and down. I also like deep amendment so as to have any interface, blurred or not, deeper than most roots, leaving them high and drained. (Since clay drains so poorly) Any merit to this, or more wishful thinking (to amend deeper than roots will grow)?

My personal minimum for amendent is 2,' the surface having 50% organic matter. I would not do this were it not for the fact that I dug out castor bean roots (annual, mind you) more than three feet down, fine roots and all. I also try to grow carrots 18" or so, they can be nice and sweet in summer resulting from the cool depths when it is hot on top. I imagine that amending is like fast-forwarding the mixing action of God's little creatures in the soil, pretending that this is, in fact, a forest, whose falling leaves and compost have stacked up so much over the years...
"You'd never catch God double-digging!" -Or angels ferilizing. Doesn't current research indicate that fertilizing at planting is a terrible thing to do?

I have hypothesized: clay, being the size particle it is, seeps with water into the fluffy container-mix of a newly planted tree, slowly but conveniently changing the rootball's soil to a more realistic one like it will encounter in future. Any truth?

I, being so young and wet, do not entirely understand roots, as I have been told "100% of the important feeder roots are in the top 8" of the soil profile" many times, but wonder about those roots I find 2-4 feet down. Do they grow along, supplied in oxygen by thier counterparts?

Thank you for sharing your knowledge with me, old wise guy.
K. James

What an incredibly repulsive border between topsoil and subsoil, Effervescent.

This message was edited Mar 12, 2006 3:18 PM

Effluence:

Wow, not a single native plant to be seen! What you didn't say is that this soil profile image is entirely unnatural, but a result of the unsupervised construction process. Which, unfortunately, has become the standard rather than the exception in developments today. The nearest you'll find to this contrast (in nature) is near a recent cataclysmic event like a volcanic eruption, tsunami, landslide, flood, or violent earthquake. Hardly soil-building events.

I am enjoying reading all the clay-mation comments thus far. I really wish you all could have the pleasure of attending an agronomy (soil science) class at least once in your lives. Aside from all the chemistry which would wear down the best of us, it presents a fascinating kaleidoscope of situations in which plants must live and gardeners must toil (example: the Invertisols in TX; check that out for a challenging growing system). And that's just in places where "man-made" doesn't turn the system on its head. All clays are not created equal.

Superstitious:

See comments above. There is absolutely no natural actions happening therein the IL pic. The dark loam appearance is compliments of a tri-axle truck bringing in some fine IL prairie soil dumped on top of some stout compacted structural IL clay subsoil, brought to you by a friendly neighborhood CAT D-9 dozer.

JamSession:

You've probably got the most aberrant of conditions, compared to the rest of the assembled commentators. Your extremely low rainfall and humidity create conditions in which chemical reactions, decomposition times, and microbial activity occur at completely different rates than those that live in higher rainfall areas, warmer/colder areas, and differing length of growing season areas. Altitude might even come into play; that's a variable I've not heard considered before.

All in all, one must do what works in one's unique area. Overall recommendations against wholesale amendment in generally undisturbed conditions are accurate. In creating a site for root vegetables like carrots, of course raising beds and deep amendment make sense, but not for permanent woodies. Lensing soils and addition of surface amendments to mimic or encourage the natural systems of degradation, decomposition, and microflora/microfauna activity should yield the most permanent positive results.

I'm too late here to add anything useful except to say that my own observations, agronomy courses, and readings mirror everything said by Delinquent. Amend clay topsoil layers in beds (with transition as recommended by Kenton), but never amend the planting hole.

Guy S.

I just talked to my dear husband. John is 99% correct. My husband paid for that clay for around the foundation and he had it covered with enough top soil to grow a lawn but "DH doesn't think they spread enough". I have no words. I am livid. Oh, the 1% John is wrong on... the process was supervised. My husband made sure they didn't skimp on the clay so he was here to supervise the day they brought it in by tractor trailers.

JamesCO, worms are not all native and they don't occur naturally in all ecosystems. Believe it or not, there are some pretty severe issues out there with the introduction of worms to regions in which they never existed.

Just wanted to add my 2 cents here[ not that anyone really cares- LOL!].

My DH and I have planted over 50 plus trees [and almost that many shrubs and bushes] on our property in the last 16 yrs. We have had amazing success with them and we never amend the soil. They grow in what we have- Georgia red clay. Maybe we just pick trees that coincidentally don't mind clay, but they seem to be thriving. I would say most- if not all- of the few trees we have lost have been due to drought.

Sometimes I think we make gardening harder than it has to be.

This has all been invaluable information folks, it is most useful.

Perhaps the distillation is this: Deep amendment is not for the benefit of trees, and not to be used on a popular basis, reserved for crazies like myself who amend more for psychological benefit than horticultural.
K. James

This has been very interesting reading. I don't have the clay problem. I don't amend not, but used to at my other place, many years ago. The soil here is very alkaline. I do add sulfur for some things. This garden where I am now had never had anything grown or planted other than native grasses and sagebrush. And I did not see any angleworms until after I had been here a couple of years. I have planted more than 80 varieties of trees. For me trees are very important, some of you have heard me say before that even before my house was in place I had planted some trees. Also no drainage problem as I live on a hill, higher behine my house and sloping downhill to the front. And this is desert country, so not a lot of rain, I irrigate from April to Nov.

I will post a photo for haleysaunt. About 10 years ago I made a plan for an Allee. Planted 10 Prairiefire Crabapples, alternating in the spaces Picea glauca conica, Dwarf Alberta Spruce. Really pretty when the trees are in bloom.

DonnaS

I have had a tough time eversince I installed Photoshop Elements 4, Several years ago I installed Adobe Photoshop Album 2.0 and have been using it since, then I saw and heard about Elements 4 and thought there were probably lots of different things I could do with that program than with A.P. album 2.0. Well that created a problem as Elements 4 wants to come up when I am using the 2.0 and I just can't prevent it. i tried to uninstall Elements 4 and can't even do that. Guess I will have to get the woman who helps me come and try to uninstall it, I don't have time now to learn how to use it, the instructions are pretty time consuming to learn, a pretty good sized instruction manual.

Anyway I could not find the photo I wanted of the Crabapple allee. Will try again later.

Donna

Donna, there is a way to set your computer's priorities so that the Elements 2 is the default program. One of the supergeeks on this forum probably can tell you how to do it. I finally figured it out by accident years ago, so it can't be all that tough, but I have since forgotten how I did it.

Guy S.

Thanks Guy, I will try to contact someone on Photos or computers forum.

I went to my photo albums and picked out a photo I took a couple of years ago, scanned it, does lose some color and clarity with my scanner but here is an older photo of the Prairie Fire Crabapple Allee.

DonnaS

Aimee - I wasn't 'slamming' the willow or maple - just making the the observation that they grow like weeds, and as Scott indicated, should do just fine in a clay soil with little or no 'special attention'.

I have a GOOD CLAY SOIL - not just clay, as some folks who've had their topsoil stripped off by developers. But, I still do not amend my planting holes(any more); I put the amendments on top and let the earthworms and soil microherd deep-cycle the nutrients.

Sounds like the more experienced gardeners would have to agree that amending the soil is not necessary. Here's an article I found on the subject that explains why in plain language. www.bbg.org/gar2/topics/plants/handbooks/shrubs/2.html
;-)

Thanks for that link Prairiegirl. I always appreciate finding anything written by JC Raulston.