Hole prep for trees

I will very likely be buying land in high plains desert that gets about 10" of rain per year. I have just started to read about greening the desert and discovered that there is way more info out there than I thought.  The purpose of this post is to gather  information to help me do research on a specific topic. The topic: is it an effective strategy to dig a deep hole - deep being 20 to 40 feet - that a tree will be planted in and stuff the hole with a variety of nutrients, organic matter, worms, etc to help train tree roots to grow deep and fast, develop stability and more quickly become water self sufficient?

Tom Connolly wrote:I will very likely be buying land in high plains desert that gets about 10" of rain per year. I have just started to read about greening the desert and discovered that there is way more info out there than I thought.  The purpose of this post is to gather  information to help me do research on a specific topic. The topic: is it an effective strategy to dig a deep hole - deep being 20 to 40 feet - that a tree will be planted in and stuff the hole with a variety of nutrients, organic matter, worms, etc to help train tree roots to grow deep and fast, develop stability and more quickly become water self sufficient?

My gut feeling is no.  I think you will have a couple of problems.  One, if you fill the hole with organic matter, it is going to settle, and before you know it, your tree will be planted 20 feet deeper than you planned  Two, I think you are in pretty great danger of creating an area that will cause the roots to grow outward, hit the edges of your hole, and start going around in circles.  This may or may not kill the tree, but will certainly stunt it if it happens.

I have had very bad luck amending the hole I put trees into.  I don't do it anymore.  I dig a hole for the tree and put it into the existing soil, no matter how poor.  I do bring in some extra soil from nearby and raise the tree a couple inches above the surrounding area.  In the desert I would do the opposite and plant the tree a few inches deeper.  After that I mulch heavily and anything I want to add, I put on top and water it in, or let the rain do it.  There are lots of videos about planting in desert areas.  I would watch all of them

If you dug a hole say three feet deep, four feet in diameter. Put a post hole digger in the hole, with an extended bit, and drilled a hole, what 6 feet deeper than the hole. Put a pipe to the bottom and pounded it as far as it'd go, and let you get the pipe back out. Put some amendments, water them down the pipe hole, more amendments. Score the edges of the drilled hole. The drill just pushes the dirt tight around it, packs it tight. So you keep scoring and adding amendments up the hole?

Some say not to improve the soil around the tree. I add sand, peat and manure lots of it, lime to my acid ground. The hardest time for a seedling is when you ship it around the country drying out and then shove it in a new spot, a soil different from its known in the past. I baby the poor thing. I know my roots don't stay in the hole, cause I've accidently dug them up.

It's your tree, do it the way it makes you happy.

20 to 40 FEET?  Or do you mean 20 to 40 inches?

A standard basement for a home is 8 to 10 feet deep.  That takes a great deal of work to dig with an excavator.   A 40 foot deep hole would be crazy deep.  You'd hit bedrock before you got that deep.

I think that the best way to prep the soil for future trees would be to lay down a HEAVY layer of wood chips and let them slowly break down.  A heavy mulch layer helps with decompaction and brings tremendous diversity to your soil life.  When you finally get around to planting your trees, your soil will be much better.

If there were a way to get tree trimmers to dump their wood chips on your land, and then if you could spread them with a front-end loader or some other way (maybe a snow plow on the front of a 4-wheel drive truck), you could just sit back then and let them do their magic to your soil for a couple of years.

The first and most important thing to be aware of when preparing to plant trees is the soil type.  Sandy and loamy soils can get away with crazy big holes with all sorts of amendments in them, though definitely be aware of the danger of settling if it's crazy big!  
     But in a clay soil this is a recipe for disaster!  When it does eventually rain heavy, water will accumulate in the loosened hole and then not drain readily away into the surrounding tight clay.  If it stays like that for more than a day, your tree will almost certainly drown.  Fruit trees are among the most sensitive.  On clay you want to plant directly into unamended soil, making the hole just big enough to comfortably fit the roots.  If there is ANY chance of it getting soggy, make a mound and plant the tree on it.  You can always water it a bit more, but getting excess water away from something planted down in a hole is going to be a challenge.  Add amendments in the form of mulch or topdressing.  If you want to put something vile down there like humanure or roadkill or whatever (and all these things are wonderful for trees!) then dig a separate hole, near by the planting hole, and bury the stuff there.  The roots will grow over to it when they are settled and ready.

Several good tips have been given by others so I'll just give you the tree point of view.

Trees do not send feeder roots deep into soil, these important roots will always be found in the top 24 inches of soil, only the holding roots (like the tap root) go deep unless the tree is growing in rock, in that case all the roots will follow the natural crevasse in the rock, which will eventually crack wider as the roots get bigger.

Knowing this, creating really deep holes with the idea of planting trees in them is more a waste of time and effort, it is also why professional tree planters dig shallow, very wide diameter holes for the trees they are planting.

Adding to the water holding ability of the soil that is already there is more important and will always work better than creating craters to fill with debris with the hope of that holding more water for the tree roots.

Redhawk

I live in a mild climate with 40-50" seasonal rainfall, so maybe no relevance to the high desert.  I've been planting trees seriously for about 25 years, and have planted somewhere between 250-300,000 now (I lost count!). I've found for me the best results come from a single spade cut into the soil, drop the seedling into the hole in such a way that ensures the bottom of the rootball is firmly on the ground, then push the soil gap closed with my foot. I always drop the seedling deeper into the soil than the nursery soil level, at times I've planted them so deep that only 10% of the seedling is showing above ground.  Everyone who sees my technique recoils in horror, but it works, and it's fast. Growing tree seedlings in Hiko-90 trays, on one occaison I planted almost 2000 seedlings before lunch one day, and every one grew (until a leaf insect defoliated them a few years later).

This is another reason it's best not to get too ambitious with gardening right away by trying to plant the whole thing in one go.

A few months ago I planted two apple trees and did just what everyone told me not to: I planted in mid-summer, which has now burned their leaves and shown no sign of growth at all; and now reading this post I realise I made a mistake filling it mostly with manure and compost, thinking it would encourage healthy growth.

Luckily my nursery won't supply trees until two months time, so I haven't made the same mistake throughout the whole property. I have hard, heavy clay soil that looks lifeless, yet the large tree I cut down always had earthworms around its trunk. I won't make much effort with the later trees: just a wide shallow dig and a bit of a mound (I always experience a problem of the mound washing away when I water it though).

When I dig a hole it fluffs the soil up. When I add my amendments it gets to be a bigger mound. Even without the compost on top I wind up with a volcano mound around the tree. Last year I dug up between two fruit trees, used the fencing and the post from the two trees, added a couple more posts, more fencing, and  added my amendments. Along the two long sides I double dug and took out the packed clay and used it else where. The ground came back to level. What I ended up with up with, effectively, was a raised bed without any timbers. Perhaps a hundred years from now the ground will sink after the amendments are used up, but I don't expect to have to worry about it. I planted veggies between the fruit trees, this year I plan to shrink the space I use. My intention is to make a comfortable place for the tree roots for the long term and make use of it for the short term.

If you dig a hole and put all the dirt back, it won't sink, even without adding amendments.

The first poster here is in the desert. Gets 10" of rain a year. I'd guess that if it's sand down 20 feet deep. or more, that the roots will find it easy to get down to that level without doing the digging. I used to sell an eight foot long galvanized auger about an inch and half in diameter. I found it to kinda useless in clay and rocks. But in a location like this it might be useful. I don't have any left to sell but check around for an auger that was intended for grounding a generator. It won't hurt the roots to have a deep hole especially if you add some compost or manure.

I heard a story years ago about a landscaper who had a $23,000 job at a new house. He went around with an auger and punched holes, dropped plants in the holes still in the pots, covered the beds with mulch and left. After a lot of legal hassles he lost over $20,000 of that which went to the guy who told me the story. If I were planting hundreds or thousands of trees I'd use different methods than I'd use If I'm planting one tree in my front yard.

I live in the high desert, 11" of water a year. I plant trees like a crazy person.

What we have done is dig the hole deeper by about 6", put biochar and manure in the hole and that's it. I don't even water.

I would not put fertilizer into a new tree hole.  You can amend it half way between the very best soil for that tree and what you have right now.  Wood chips can go on top, but not in the bottom. Over time they will rot and provide nutrition for the tree. If you put them in now, they will mess up your carbon/nitrogen ratios.   In the desert, your tree might dry out, especially in the summer. Trees need typically more fungal soil than what we typically have, and surely more than what you've got in the desert. If you've got old, rotten wood, that is what you can put in the hole.  It will act as a sponge and stay moist in the summer so that the tree has that tiny bit of moisture to get it through the hot, dry months.  It will also provide an incubator for diverse soil microbiology.  Here in wet compressed clay we would probably add gravel, but I'm sure you've got great drainage, so don't worry about that.  I agree that if you have a few trees, you can put a lot more attention into them than if you plant 1000 or 10,000.
John S
PDX OR

Hi Tim,
I plant trees into mounds and find that mulching them and watering them with a watering wand or some other gentle means helps a lot to keep it intact.

My experience with tree hole prep in general is different than some who have already commented. I learned to plant trees from two different women who amended the soil where they were planting, and their trees thrived. They both have established permaculture orchards that they have worked on for years (decades for one of them) and add to every year. They each have a heavy clay, and so do I. My trees have all flourished. I can't offer an explanation, but I just want to say that not everyone's experience is the same. As for the hole filling with water, I haven't seen that to be an issue, though I build hugel beds in between my trees which seems to help (I have a very high winter water table)

Thanks for the diverse input.  The hole I was thinking of putting in would be only 1-2" across, not any bigger.  I was thinking of planting only trees that have tap roots - I am not sure if that is a good strategy in the desert?  i was thinking that the hole would facilitate the tap root to go deeper more quickly....have much to learn.  I am also looking into how covering the ground around the tree with rocks would help.  Something like this is used to harvest water from air (condensation).  Also, are there forms of helpful bacteria that can be introduced to the ground - 2 feet or more below - to help start changing the ecosystem naturally - even kinds of mushrooms?

The microbes that you would most need would be fungi.  The thing that would most help them would be old rotten wood, which already has the fungi and the food for them (the old wood). It also provides a sponge-like source of long term moisture below. New wood chips in the roots would mess up carbon and nitrogen ratios. Wood chips on top would not, but wouldn't help the soil for quite awhile.

John S
PDX OR

I built a chicken coop and run on greater than 10% southern slope, and thought it would be a great idea to put my 7 layers of food including apple trees down hill on terraces inside orchard/chicken fence.  No chicken poop should make it off my property due to heavy rain; however I read about a year later to take it easy on applying nitrogen to the fruit trees.  I previously just figured if I'm extracting materials off the fruit trees they need a bunch of things returned.  Like Nitrogen being in the top 4.

So we just like our trees, have a place in time and some developing to do along the way.

Apple trees and chickens are a good combo. The chickens eat the codling moth and apple maggots in the ground before they can fly up and bore into the apple. Good for the chickens, good for the apple tree, good for you.
John S
PDX OR