As I keep saying at every opportunity my soil is basically rocks with a bit of gravel to glue it all together. My tree holes are about 3 feet wide by foot and a half deep, basically an in ground 75+ gallon pot. And a pot it is; roots can’t penetrate a single inch of that glacier moraine crap. These conditions turn my trees into naturally dwarfed trees.
But some are more dwarfed than others and need more growing space so I’m re-digging some of my holes. Looking at my handiwork this particular hole was smaller than my usual and the tree is growing even more dwarfed than usual. Hard to believe but the tree on this picture is on its 6th year in the ground. Greens up and crops well but it just doesn’t grow. It is supposed to be on a semi dwarf (80%+) rootstock. This year I’m taking the time to expand the hole.
I’m only doing one side so the tree doesn’t get extra pissy. It is about 18" deep, 10"+ inches wide, and it should add about 20 gallons or so of soil to the tree. Next year when I do the other side I’m hoping that the tree will be satisfied.
We can hit temperatures in the -20s F and the temperatures can fluctuate a lot. I like to keep the root ball below soil level in order to keep them protected from that and from warming when they shouldn’t. For instance we usually have a January meltdown with temperatures in the high 40s for a week, followed by sub zero temperatures. A raised tree can lose the snow cover and the mount would quickly warm up. That’s a great thing in the spring but not in the middle of winter with more to come.
Here in Alaska we plan not for the average winter but for what we call test winters. That’s when mother nature decides to jump a whole USDA zone, with no snow cover, after a warm spell. Believe it or not I have trees and bushes that can shrug that off.
You probably have it worse than I do, if nothing else I don’t have to worry about drainage. Hopefully you can use the mound system.
For the most part it is well cured horse compost with a bit of top soil. I mulch with a heavy layer of green mulch that keeps decomposing so while the “mix” I use keeps settling, the mulch layer keeps building it up.
Your best bet is to buy several yards of top soil, the sort of stuff they put down to lay a lawn on new construction. By the truck dirt is well, dirt cheap. It would be a bit heavier/denser that I would like but if you could mix in lots of compost it would work great. The trick is that if you put stuff in there you know will lose volume you compensate by starting it bigger.
I see some grass growing on your soil. Does it have roots? I’d think so. It may be poor soil but I doubt it’s as poor as you are making it sound. Normally roots grow well in rocky soil. It’s just poor soil with low water holding capacity and low nutrients. But unless it’s cemented then roots will grow in it.
Some have criticized the method and said his results are overblown, or at best not a panacea. He is on the Olympic Peninsula with very similar glacial outwash soil. His stuff seems to grow amazingly well. There are some heavy evangelical overtones too, so if that’s not your thing, that may be bothersome.
I’ve used large volumes of wood chips over certain areas and it is impressive how it transforms the productive capacity of the soil. The biggest hang up for me is where to get enough wood chips. Also, having to find the time to spread them. For years I did that type of work by hand, and now that I have a nice tractor with loader, a lot of my trees are big enough that access is trickier.
That’s the 3"~4" of soil that was thrown on top for the lawn. On the area without said treatment when they did the foundation for my story and a half garage/workshop all they did was to scrape the surface of debris and then plop the cement forms on top; there is no organic material whatsoever to get in the way. The valley I live in is an ancient glacial moraine.
Heck ask the tree, 5 years in the soil and the roots have not been able to penetrate that mess 18 inches away from the trunk.
I’m a big promoter of that as well. His words are true. You can also mix a little into the poor soil. It should help hold moisture in your rock bed.
It’s straight clay and rock here. Not quite as much rock as you, but close. It will take longer for everything to get established, but after it does your good.
i agree. i have rocky clay soil. at least here the roots have something to grow into if they can punch though. pure stone like that makes a deadzone for roots. i would pile and spread as much sawdust . woodchips, woods duff… anything organic on top. over time as it rots it will fill in those pockets in the stones. another great amendment/ fertilizer if you can get it up there is alfalfa pellets. they have a n.p.k of 2.5-2.5-2.5. i pay $17 for a 50lb bag at T.S.C. mix it in with your woodchips/ manure. where do those farmers that have horses get the grain/ hay to feed them? i wouldnt think much of Alaska could grow those crops.
reason i told Don to mix with more coarse mulch is they have a tendency to pack down and repel water. a little mulch mixed with them or a quick fluff with a rake takes care of that.
