I think that’s what create the problem in the first place.
Clay soil is largely a drainage problem. Digging a hole and amending the soil creates a bath tub effect where water can’t drain and ends up drowning the plants. If your plan is to amend the soil you have to think long and hard as to where the water will go. Else you are better off doing no amending at all; the tree will find its way through the clay and you improve watering with a very thick layer of mulch on top.
Even the mahaleb rootstock?
Would making a 1 ft mound work?
Plant roots need water, but they also need to breathe. If you create or encourage a situation where the soil becomes saturated for an extended period of time no root stock will save the plant. Think of it as the difference between drinking a glass of water and having your head held under water.
The 1-foot mound works because it helps with drainage but you still need to avoid low spots where water can collect. Soggy roots can weaken and even kill some plants and the anaerobic environment creates the wrong sort of fungi and bacteria in the soil.
You recommend making the mound with clay or have to add topsoil to the mix?
i use well-draining bagged soil when planting on mounds, mulch on top of that to hold soil in place. in 5 yrs. the mound will have broken down and becomes flat. i plant everything like this and they grow great.
Once you build up or partially build up you can use potting soil if that’s what you have.
The key takeaway here is that clay problems are primarily a drainage problem, and secondary an irrigation problem. If you can ensure that water can drain away you are golden. You can build the sloping trench where excess water eventually flows at the end, or you can build up where excess water drains from the mound.
Either way a big fat cap of the correct mulch is the most awesome thing in the universe. I’m a huge fan of green woodchips from sub 2" branches. It has been bone dry here but because I have like 5" of mulch around the trees I can pump a lot of water and the mulch soaks it up without letting it run off, then slowly drip it into the soil. If you are planting into straight clay you want tons of mulch to keep the soil from drying because once it dries it is not trivial to get it wet again.
Can you explain the drying clay piece?
I had to remove my mulch around the trees since it was keeping things too wet. So, I removed and it’s helping things dry quicker (or at least it seems like it).
i totally agree. i put down 4in.of arborist mulch every spring. my plants survived 2 summers of drought in a row with little to no watering. the 7 years of mulching has really helped my plants grow well. i even put a thin mulch in my veggie beds. in fall i turn it under. by spring its ready to plant again.
I have heavily amended tree planting holes on sand/rock soil. When I water, the heavily amended soil soaks up water like a sponge in record time. The sand/rock surrounding the hole drains excess water just fine. In 2 minutes I can dump quite a few gallons of water that go straight down into the soil.
On clay; if you spend 2 minutes irrigating a tree chances are 90% or more will just run off. If you dig a hole immediately after watering you could find out that the water did not go past the first inch of soil.
So you create moats around the tree to hold the water in place, giving it a chance to soak in before running off. You also mulch heavily as the mulch holds the water that slowly percolates into the soil and stops it from evaporating away in the first place. You also want the mulch to keep the roots cool. This may sound stupid but trees grow in forests, which have cool soils rarely exposed to direct sunlight. You recreate this by mulching heavily which in turn promotes the sort of soil life that makes the tree thrive.
Clay is a fine medium to grow trees in but it is a whole lot less forgiving of the mistakes we love to make.
Did you fill the sides around the tree with rock? Would making relatively horizontal line of gravel out of the planting hole help drain water like a small pipe?
No, my native soil is 60% rocks, 40% sand and gravel. When I had my garage built they didn’t even need to tamp down the dirt work, just remove the skin from the top as there was no organic matter to speak of.
I noticed my pears getting red-tipped leaves of the new growth, which I learned is a sign of overwatering typically. When I dug a whole to see, the clay/top soil was like mud. So, fairly saturated. I thought that removing the mulch would help dry the clay more thorough between deep waterings (from a 5 gallon bucket).
So doing the makeshift gravel “pipes” is useless?
That’s what though too, my soil is also like that where if it rains heavily you can see mud on the topsoil in some spots for some time.
You should do a soil percolation test to see what you have. Dig a 1’ by 1’ by 1’ hole, fill it up with water. Fill it up again in the evening and keep it nice and full for at least an hour. In the morning fill it again and time how long it takes for it to drain. That will tell you the percolation rate of your soil.
I’ll try doing that
I agree planting on mounds/raised and adding organics; drainage is a problem for us and our heavy clay
In the spring I am going to plant iron&clay cowpeas as a cover crop around our home orchard after our last frost date. They mature in 3 mo, can grow in shade, have deep roots that can break clay, are legumes so nitrogen fix and are sensitive to frost so will die off and add a lot of biomass/organic matter in the fall (without the added work of tilling them under); you can also eat them (aka black eyed peas) and they dont seem expensive (for seeds) and have many many vendors
They will attract deer, who will forage it, and so it might create a new problem or worsen an existing one. To be determined for us.
Anyway, I have not planted them yet but this profile seems attractive for our heavy clay soil and will help remediate it through its deep root structure, nitrogen fixing and then after the season, the no-till increase in biomass and organic matter.
ideally, I will supplement the cowpea plantings in spring with compost and wood chips in the fall. I just need to talk to some stables and arborists around here.
Could use a broad fork, or any forking type tool to loosen up the soil, then apply a compost mulch, sow daikon radish, maybe some thick carrots Chantenay carrot is a variety that comes to mind. You could possibly dig up the trees and mound them, Akiva Silver who operates Twisted Tree Farm in New York, most of his property is clay, and he highly recommends to mound trees it’s worked out great for him!
My context is similar, but I deal with machine compacted soil, with big rocks all squashed down back in 87, I have to take a pickaxe to just get a few inches down. I haven’t seen any cracking despite being through 2 droughts, so it’s most likely my soil doesn’t have much clay - but in my experience loosening the soil with a broad fork and or any tap rooted plants like carrots/daikon can go along way.
I say mound your trees, plant daikon/carrot and clover around it to prevent erosion and observe/interact!
The problem is the volumes the OP may be facing. If the soil is indeed bad clay and little else (lots of good minerals though), trying to amend it with a root here and forking some organic there is not going to go far at all. Think about trying to amend with even 33% organic matter 2 feet deep…
So first and foremost it is a drainage problem, not a soil composition problem. Meaning that if that is not working as it should it is a very effective way to kill trees slowly. I have memories of digging dead plants for what was pretty much a in ground chamber where water would deposit and not escape. There is a very particular smell you get when anaerobic bacteria is in the mucky soil.
Once the drainage issue is taking into account, building up, way up, is the least painful way to go (albeit still with quite a bit of pain). Ideally, working the first 12" of clay with amendments, and then mound per tree, or go all-in; build 2 more feet up evenly with top soil and compost.