Planting trees/shrubs into clay

Have heard everything from amending clay and scraping sides of hole to prevent glazing to no ammendment and clay right back in hole ( never worked for me ) to what I have been doing which is till up a huge area of clay then plant on top of this area with better soil and mulch to create a mini raised bed. The concern is when roots hit the clay level will they continue or just ball up? Not so worried about small shrubs but the bigger hedges and tress. I have had very good success with Hydrangea and Blueberries. I tried it with a Little AnNE Magnolia and it shot up then stopped growing. I had to move it due to a swing set blockin sun and when digging it's root system didn't really amount to much. I moved a few other bushes and tilled pretty heavily and they are little off shoots so hoping they can establish in the clay. In front of the house I pulled all the clay up and put in good soil. Those shrubs are going crazy but it's back breaking to remove that much soil and in areas of single plantings doesn't make sense. I am now leaving about half the root ball ( 3 gallon or bigger ) above a tilled layer and using better soil and mulch. This after killing a few hundred plants. Thankfully a friend is a grower so it wasn't financially bad. Just curious to hear what others do in this thick heavy clay? There does appear to be a rock/sand level about 2 feet down. Maybe if I dig to that it will allow drainage but still won't help roots grow into clay.

Thinking this guide makes sense.http://www.rodsgarden.50megs.com/clayplanting.htm

I planted every bush, tree, plant in my yard, and did most with a pick ax or Maddox. For the trees, I dug out a hole at least three times the size of the root ball in diameter, and just deeper by a few inches, then scarred the bottom of the hole enough to let roots take hold. The deeper you go, the harder it will be to keep the tree watered enough since the water will flow away from the roots. I've had good success with magnolia here at my house, except for a really bad tree I bought at Sams which had bugs like I've never seen before.
Clay is tough, but once established I've had good luck.It's water, water, water in the hot dry season that seems to be the deciding factor whether they live or die after the first year.
I've got apple trees planted into the red sand layer, and they don't do as well as those planted in the harder clay layer. I think they don't keep water on them as long and the sand doesn't hold nutrients like the clay does.

Common myths:

Amend the full dirt- NO. Dirt needs to be the same as the dirt surrounding the hole/fill. Otherwise water will go into the amended soil and sit while the clay surrounding it doesn't allow for equal drainage.

Planting deep- no no no hell no. Trees will sprout advantageous roots that will circle the trunk and girdle it. Plant a little high if anything.

Two most common causes of seedling death. Over watering. Under watering. Also going from one extreme to the other creates a prime environment for phytopthera (root rot).

You do want to make sure the hole isn't glazed.

Tease the roots out. If you can't do that, take an ax and make four cuts. Yes it's OK to cut the roots, but cut them at 0, 90, 180 and 270 degrees, blade direction lined up with the tree. This some what eliminates the circling and potentially girdling roots.


Planting procedures do not change based on soil texture (clay/sand/etc). Just watering to make sure they're watered accordingly.

Clay is subject to compaction more so than other textures which creates a whole issue of its own. A tree may do well until it outgrows its hole and hits compacted clay soils. I won't go into that, other than to just say make sure you're not planting on a compacted site. It takes way less weight than most think, to make a huge difference in root health.

If I'm thinking of planting a tree in a spot, I'll always dig the hole, fill it full of water, and if it drains out within an hour, I'll plant the tree there, if not, I'll plant something else that won't have such a large root ball or structure there. I've got several bush hydrangeas planted in holes that were going to have trees in them but didn't drain well enough. They seem to do great in that condition since the hole was dug for a tree sized plant, and can still get rid of water enough to let that plant live.
I do amend the clay I take out of the hole, I break up the big clumps, take out all the large rocks, and mix composted cow manure to about a 1:4 ratio with the clay I took out. That seems to keep the clay from getting so hard, since bagged manure has a good amount of sand typically.

Eric, adding manure isn't bad, but replacing it with say a sandy soil in a hole in clay is just going to allow water to infiltrate into the root ball and sit once it hits the clay underneath, rather than permeate slowly into the root zone as if it were all clay.

So of most of your yard is clay?? I did ammend a huge area for gardens ( veggies) and under our building is now the nicest blackest soil but thats because I built a huge bed that got flattened by a logger. Now that I know not to dump it into the hole and rot roots I have better success. Some trees are doing great in hard clay. Others not so much. Deep rooted trees are what I wonder about but not planting any in this house. Just future reference. So no one advocates raising root ball above ground level. Even for shrubs? Seemed to work and my shrubs are ridiculousin growth especially this year. Maybe a one size fits all solution is my problem?

I have been tilling soil slightly ammend with woody mulch and making the area 10 x the root ball where I can but in 10 years or less it will probably compact. I read somewhere tilling in uncompleted humus was bad but it seems to have worked in my big gardens. About 20 truck loads of chipped bark and some loads of leafy mulch all tilled in 2 years ago and now soil is black and earthworms galore. Not willing to do that to my entire yard though.

Justin said:

C
Clay is subject to compaction more so than other textures which creates a whole issue of its own. A tree may do well until it outgrows its hole and hits compacted clay soils.

Click to expand...

And here I thought my father-in-law was pulling my leg about trees in clay. But he swears it makes planting trees a frustrating prospect. The only thing they've gotten to grow is river birch and bradford pear.

Justin, why one species and not another? Thanks in advance, sir.

Not all clays are the same. Some drain well, albeit slower. Some drain poorly. Some have shrink/swell issues. I can't really throw a blanket statement out about them.

Some of my yard is very compacted from the earth moving equipment used to excavate the site years ago, and some is less compacted and can actually be dug into when damp. There are even spots of red and yellow sand in the upper levels of the property that you can sink a shovel into with just a push.
Most of what I've planted into is the hard, rocky clay with all the quartz and granite of the area and all the topsoil hauled away by the folks that did the excavation originally of the property. It's been very challenging to figure out how to plant things that will actually grow in this stuff. My garden spot has almost zero native soil, it's all composted feedlot cleanout.