I find the blanket statement that you should not amend the planting soil because it is better for the tree or bush to use what is there a weird thing. Here is a good example as to why that doesn’t work all the time. Without further ado, I present to you guys my soil!
For starters bellow the few inches of top soil about 50%+ is composed of this:
Pure sand and gravel, naught a speck of organic material. Most of the Matanuska valley in Alaska is like this; glaciers that bulldozed the mountains and spread the moraine for hundreds of miles. The plus side is that I have 0 drain issues. The minus? well sand has near 0 ability to hold onto nutrients and slightly better than 0 on holding water… Heck I still count myself lucky that I’m not dealing with clay…
The blur above the hole is a pink champagne currant. The hole is as deep as it is wide. Deeper than the expected depth of the roots but that extra mass is meant to help hold onto humidity. For this particular hole the soil is going to be 50% horse compost (5+ years old), 50% of the sand that came from the hole.
Power tip: get these sifters. They are used in mining to process material you want to run through a high banker. They fit the mouth of a 5-gallon bucket. The first screen I used to remove the big 'uns was half an inch, the one I use to fill the hole is 1/4". Why? Because all these pebbles can’t hold water, can’t hold nutrients, won’t do anything for the plant.
After a good mixing with the shovel it is time to flood the hole. Done two or tree times just to play it safe. Then some more shoveling to make sure everything is properly wetted. I wait about an hour for the excess water to drain.
And finally the end product, with a few inches of green mulch and the anti-dog hoops (doggy likes to carelessly run around…). Between the soil being well wetted and the mulch keeping it from drying I won’t have to water again for a while.
I used to put some vermiculite for water retention but after having the opportunity to dig up a hole a second time (winter killed plant) it looks like the organic material plus the mulch on top is enough to hold plenty of humidity.
One caveat; When I plant trees I set it so the bottom rest directly on the sand; otherwise the settling of the organic material can cause the graft joint to sink too much. With most bushes it doesn’t matter as much. This currant will just put new growth and new roots as needed.
Wow, I thought I had it bad. You make me feel lucky.
My back yard is ~6-12" of good topsoil over cobble over sand. I think the rocks are glacial deposits. It takes me half a day to dig one good hole for an apple tree. Driving fence posts is torture.
I amend my planting holes too. It maybe overkill, but I dig out an area roughly 4’ square and 2’ deep, removing the rocks / boulders. Then I throw back the sod, forming the lowest layer. Then I add compost and mix it with the original topsoil. Finally I put back the sand, which used to be the deepest layer but now covers the surface. I figure that the surface can be porous and non-fertile.
I think my soil, here on the eastern slope of the Continental Divide of Montana, looks about the same, except that my PH is about 8.3 and I have to add elemental sulfur on a regular basis to lower the PH.
Yep. There are plenty of things that grow fine and very productively in clay.
I don’t amend planting holes but you give a good example why each situation is different and blanket statements always have exceptions. Looks like you found what works for your site.
Topsoil? What’s that? The first few feet of my yard is construction in-fill from when they carved the lot out of the side of the hill. Not a lot of nutrients except what I add.
Honestly, with the exception of the rocks and boulders that makes it a nightmare to dig anything, it is not a bad situation. In the long run I think drainage issues are worse. We may have a crazy short season but sun loving plants go crazy when we start hitting 18-hour days.
For bushes; in the spring I put a 5-gallon bucket of compost mixed with the old mulch, and a bucket of fresh mulch on top of that. By the fall the mulch has pretty much decomposed down thanks in part by liberal urea fertilization over the growing season; the nitrogen speeds up decomposition. At that point another bucket of mulch gets added for winterization. That is 15 gallons of material that each bush gets every year. In a few short seasons the soil gets what a forest floor would take hundreds of years to build up.
And it works pretty good. Check out this baby dandelion. First year growth. By the time the head has grow a few inches the root has gone crazy. Being on the humid soil under the mulch I was able to grab it from the top and wiggle-wiggle-wiggle it out without breaking it.
I’m a big fan of adding green mulch on top with a good helping of compost once a year. This turns the first few inches of soil into a perpetual decomposing layer just like in a forest floor. When you do that the tree will send up a lot of feeder roots up, so I wouldn’t write it off as not being used by the tree.
Top soil is the few inches they laid down to grow grass. The rest of my yard looks like a gravel pit. I could drive heavy machinery with the ground soaking wet and not worry about sinking or even messing up the surface.
@don1357 – I agree about the value of organic mulch. I’ve actually been covering the soil with grass clippings to suppress weeds. That’ll decay into good stuff. I also save and compost most of the leaves each autumn. What doesn’t go into new holes eventually goes on top of old ones.
I have one caveat and corresponding concern. We have lots of voles. Organic mulches can make great sites for vole nests. Dried grass clippings would be primo vole nesting material. So I have to be careful that I don’t create a gigantic vole motel. Otherwise I could end up with trees without roots.
Now my usual practice is to rake mulch away from the trees for the winter. Plus use vole poison (Zn Phosphide).
There is an island in Ladoga lake in north-west part of Russia called Valaam. It is a home to Valaam Monastery. The island itself was just a rock, however monks grew the garden there. Where did they get soil? Everybody who was coming to to the Monastery was required to bring a bag of soil. Not gold, not money. Soil. At least this is what legend says.
Some day our grand kids will hear Alaska legend…
floodplains along the st. john river here are super fertile. when all the ice / snow melts with the spring rains it floods these fields along it and deposits organic matter washed out of the woods upstream. by mid /late may the water receeds and its able to be planted. i go down there and skim the deposits from on top of the river bank to bring back to add to my plants soil.
i broke-down and hired a gent with a mini backhoe. had him dig about 15 holes and remove trees. it was life-saver. we add about 20 wheelbarrows of soil to each hole. yup don1357, ur soil has + / -.
to the general reader: making ideal tree plots (holes) is worth your time. sandy soil?
i grew giant fruit trees in a desert town in california. in pure sand. i visited the local horse stables and hauled TONs of … as little poo as possible (it was hard to miss) and as much hay & alfalfa as I could gather. maybe 40/60, poo/not poo. then dug a hole that a small car could disappear into (i was in my 20’s). mixed my horse goodness with sand. add water. daily. then watered some more ;). the trees exploded. apple, nectarine, fig, plum…and i can’t remember much else… clay soil?
in maryland we have some spots with soil so hard it’s like concrete. it was 2017 and i just started the current orchard. used a pick but… ultimately, i largely planted over the soil. i went as deep as my strength allowed and then built a giant mound over the top (black compost, rotted woodchips, native soil). lined the tree plot with rotting tree material from forest. it all settles after time. HEPPY holes
we dig 5’x5’x~18" holes & filling-in holes with 1/3 black compost, decomposed woodchips & the native soil (loam that leans to clay). we create 12-14+" high mound and set our girls in the middle of that. the holes are a LOT of effort but some fruit trees last a lifetime. the up-front investment in time means a healthier tree (less care), years of premium fruit, and more fruit. no worries about drainage. it does mean more pruning
dig Forrest dig!!!
One general rule that you can follow if you have bad soil is to amend the soil so that it is halfway between what you’ve got and the best possible soil for that plant.
I agree with your basic premise. When I started planting fruit trees here in soggy clay, they drowned in the winter. Dead trees don’t adjust to the soil. I started adding rotten wood, pumice and gravel and they drained way better. Now I’m adding biochar and they do even better. You are making it work.
im lazy. i lay 4’x4’ cardboard on my rocky clay ground. if sod i cut a 4’x4’ piece out and flip it back in upside down, then cardboard. push a stake thru the center of the cardboard in about 12in. tie tree to stake. mound with preferred soil. tamp well then mulch with woodchips to 4-5in. water in. if you add more chips every spring it will keep weeds out and keep feeding the tree. no worries of the tree drowning or getting root bound as it forces the roots to spread out then anchor in once the cardboard breaks down, rotting turf feeds the trees and lets air go to the roots… the stake holds it in place untill that happens. have many dozens of trees and bushes planted this way and are doing great. after 3-4 years the mound disappears as the tree eats the organic matter out of the soil beneath it.
I probably could get away with that but I like to keep my plants flush with the soil. Mounds expose the roots to more cold in the winter time.
My main tree area is on a gentle slope with 9 trees in 3 rows. If I had clay I would have rented a back hoe or similar and trench it 2+ feet wide down the slope, then amended with a ton of organic. The trench of organic would then allow for perfect drainage down the slope while the tree could still benefit from the clay’s ability to hold onto both nutrients and water. These are the sort of shenanigans us small orchard people can get away with; if you have a thousand trees you can’t affort to be *king around with each one of them.
my mounds are pretty minimal once they settle esp with bare root plants and once turf rots. a few have even gone the other way and made a slight depression. id think 6in. of mulch would protect your roots from even the worst cold. with the amount of plants/ trees i planted in in the last 7 yrs. i would have had to take a 2nd mortgage out on the house to hire a backhoe each time.
I agree. I also put wood chips on the surface. Research has shown that trees and woody plants need fungal soils. Most of our soils are too bacterial. Elaine Ingham has done a lot of research in this area. Linda chalker scott too. As the wood chips get eaten by fungi, they add life to your soil. The mycorrizae can find nutrients and water elsewhere in the soil and share it with other plants.
John S
PDX OR
Our soil is mostly yellow clay, sitting on top of fractured limestone. Good enough to make bricks/pottery with. Holds moisture extremely well, and is a good source of most plant nutrients (Nitrogen, obviously, excepted). Provide it with mulch on the surface, and earthworms thrive, thus assuring drainage all the way down to the limestone For trees, this is as good as it gets in my opinion - good anchorage, good drainage, good mineral content, good water retention, good CEC.
For gardening, clay is much harder. Gardens get much more tillage. We’ve raised the organic / loam content of our gardens over the past 40 by continuous mulching, adding charcoal (an enormously under-appreciated soil amendment), to where it is now an easily worked, friable loam. A hard, heavy rain still turns it rock hard though. It’s still 90% clay, after all.
Not all clays are the same though. I grew up on a farm where 200 feet of blue clay overlay the bedrock. It was just short of bentonite in it’s water holding capability. Nothing drained through it. Every depression in a field was a wetland in a wet year, until evaporation and transpiration dried it out in mid summer. True prairie pothole country. You could grow trees in the topsoil that sat on top of it, but not in the clay itself
I think that the main issue is that it is easier to make rookie mistakes with clay. Once the tree is established it is as happy as a pig in mud, before that happens it is rather easy to kill it by mistake.
Heck lots of people end up drowning young trees and bushes with too much care (in this case water). This is doable but a lot harder to do with loam and sandy soils.
There are forests turned into farmland with super fertile soils.
