For in-ground fig, in a 60 gallon hole, should I pour soil mix directly into hole?

General Fruit Growing
#1

I am going to plant a Boysenberry Blush directly into a 64 gallon hole I dug, in the corner of my yard.

Should I pour my soil mix directly into the hole? Or place something like a Grassroots no-till fabric pot inside the hole, and then fill it with my soil mix?

I’m wondering whether I should place it inside a pot, to prevent vine roots and other nearby plants from “stealing” nutrients from my nutrient-rich soil mix.

I’m in San Diego (10a), in Southern California, and the soil here is pretty nutrient poor, its hard packed clay and sand mixed with rocks for the most part.

#2

You should first test the hole to make sure it drains. Add about one foot depth of water to the hole and see how long it takes for the water to dissipate. If longer than 24 hours then you need to add a French drain.

Do not use soil mix solely from bagged products. Mix in 1 cubic ft of All Purpose Sand (sold in bags) with each 2 cu.ft. of bagged soil mix.

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#3

Agree with Richard, also be careful to avoid planting it any deeper that the original depth, if anything err on the side of more shallow to prevent tendency to grow suckers around the base. It will likely settle some after planting so avoid adding soil any higher than its original soil line. After settlement you want the soil line to be at its original.
Dennis
Kent, wa

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#4

Usually you want to use the native soil mixed with your amendment, in your case the soil mix. As stated you want to watch out for drainage issues else you end up making an in ground tub that will kill your three. Lastly, just control undesirable plants nearby and don’t worry about wandering roots, there is no helping that but a healthy three should not be bothered much by those.

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#5

But you’re in Alaska. I’m an expert in metropolitan San Diego county soils.

Your other pointers are right on target.

#6

I don’t think it matters much where you are. The reason why you want to mix native soil, regardless of how shitty it may be, is because you want your plants to actually go beyond your planting hole. If you fill the hole with perfect soil there is a chance that your tree will not send roots beyond the original hole.

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#7

@don1357
It’s not going to happen.

#8

And yet it happens.

Soil is a very complex environment full of life. Most bagged soil is a sterile medium. Part of the healthy growth of a tree involves said tree “mating” with the soil biota, from bacteria to fungi to everything else. Mixing native soil works for both your soil biota to quickly colonize the new real estate, as well as to introduce and acclimate your three to where it will be for the rest of it’s life.

This is why often it is advisable not to amend at all; a tree is better off mating with the native soil, which promotes the roots to keep on spreading. On a hole with foreign medium there is actually a good chance that the tree will mate with that oh-so-much-better-soil at the expense of not reaching out beyond.

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#9

@don1357
You are imagining a soil that doesn’t exist here.

I’m done with this thread.

#10

No worries. Best wishes in the new year.

#11

Amending soil when planting is no longer recommended. Many experts disagree with Richard. For example: https://puyallup.wsu.edu/wp-content/uploads/sites/403/2015/03/soil-amendments.pdf

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#12

To put that article in a succinct fashion, don’t amend a hole, amend the whole.

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#13

Thanks Don - I’ve been hearing something similar.

Been trying to figure out the best balance of adding nutrient to the soil, while setting up the roots for success (in the form of growing past the original 60 gallon hole, as figs are said to grow ~10 feet deep and ~10 feet outwards).

Some say 50/50 mix of native soil to my own soil mix.

Some say 100% native soil.

Some say maximum 5% organic matter, mixed in with native soil (as stated in the paper linked by Vlad).

I’m all for nature doing it’s thing, and coming from no-till container growing, my inclination is to add as much organic amendments possible. But maybe 100% native soil, and just top dressing would be ideal. Still trying to figure that out - the ideal ratio of organic matter to the native soil (if any).

I don’t know much about soil microbiology, but I know it’s important. I have a organic worm bin, which I feed organic scraps and organic amendments to (ie. kelp, crab meal, malted barley, oyster shell powder, basalt, etc). That should add some good microbiology as well, no? (Those worm castings).

Right now my idea is to fill the 60 gallon backhole with:

  • 5% organic matter (1 gallons bu’s blend compost, 1 gallon worm castings, and 1 gallon peat moss = 3 gallons total)
  • 2 gallons of pumice

That would be 5 gallons of additives into the 60 gallon hole (8.33% additives), however only 5% of the additives would be organic matter (the compost, worm castings, and peat moss).

I also was told it could be good to create a 6" raised big flat plateau above ground level, and make that 70% native soil to 30% of my soil mix (40/40/20 of pumice / peat moss / compost).

How’s that plan sound to you guys?

(Or would it make 0 difference, and just plant into native soil, just top dressing with my worm castings?).

Ideally I would dig 2 holes and test it out, but I don’t have room for that.

Thanks for any suggestions!

#14

It depends on your soil to begin with. Me? I actually amend the living crap out of my soil because I basically have gravel and rocks/boulders. After shifting it through a 1/2" mesh screen about half of my volume is already gone. In addition the packed gravel/rocks get hot as hell; when I dig a hole in the summer time I can touch the rocks a foot below and they are warm. The amended soil under my trees is moist and cool to the touch at the surface, let alone deeper. I use a ton of well cured horse manure, I picked about 3 pickup beds full of the stuff last year and they should be ready to go by this spring.

Start by figuring out what problem needs fixing, and then make sure that you do no harm trying to do some good. What does your soil looks like?