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Author Topic: Best tree for shallow soil?  (Read 199 times)

Mango Stein

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Best tree for shallow soil?
« on: September 12, 2017, 01:34:16 AM »
We're talking 6 inches before hard rock. Though I can build a mound of perhaps a foot. Total 18 inches.
My options are:
- avocado (grown from seed)
- biriba (dwarfed on A. montana rootstock)
- asimina triloba
« Last Edit: September 12, 2017, 04:43:27 AM by Mango Stein »
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fyliu

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Re: Best tree for shallow soil?
« Reply #1 on: September 12, 2017, 02:09:56 PM »
You're basically growing a bonsai tree. Probably many things can work, with more maintenance work. Soil dries up faster, etc..

You might have to cut the taproot of the tree. Then provide support for the branches so the heavy top doesn't fall over without the taproot.

Some plants really like their taproots, so those won't work.

Ulfr

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Re: Best tree for shallow soil?
« Reply #2 on: September 12, 2017, 04:45:48 PM »
I have seen very big trees growing in very shallow soil and I am betting so have you. Many of our natives make a living that way, where abouts are you? Roots can go a long way sideways and depending on the tree can work their way through cracks in the rock. I would pile the mound and mulch out as wide from the tree as you can.

How is the drainage and what type of rock? Avocado would be one I wouldn't try but I think a heap of others could work if drainage is ok.

My grandfather is on a similar very shallow top soil over shale and has very established macadamia, citrus, annona, bananas etc. The drainage is good though. The macadamia is quite big, I have to imagine it has broken through the rock.
« Last Edit: September 12, 2017, 05:07:22 PM by Ulfr »

Mark in Texas

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Re: Best tree for shallow soil?
« Reply #3 on: September 13, 2017, 08:22:33 AM »
Grafted avocado, 12" raised bed.  You could also use Rootbuilder which I do.  They're bottomless, can be expanded in size, 16" tall.   

spaugh

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Re: Best tree for shallow soil?
« Reply #4 on: September 13, 2017, 11:31:23 AM »
I was thinking the same thing as Mark.  12" raised bed.  I would go at least 1 meter square, 1.5 meter square would be better.  Use a jackhammer to bust up the bed rock a little before piling in the dirt.  Avocados like well draining soil like decomposed granite if you can get some DG mixed with a small amount of compost to fill the bed.

Triloba Tracker

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Re: Best tree for shallow soil?
« Reply #5 on: September 13, 2017, 03:26:02 PM »
Asimina triloba reportedly is one that is dependent on taproot.
However, some nurseries (e.g. Forest Keeling) growing them successfully in root-pruning pots with tiny taproot.

Seems like it wouldn't be a great candidate for your situation, but perhaps it would work.
One thing I've learned with plants is that there are very few absolutes.

As mentioned before, A. triloba does require chilling hours in the 32-40F range - it is definitely a temperate tree.
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Mr. Clean

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Re: Best tree for shallow soil?
« Reply #6 on: September 13, 2017, 04:11:28 PM »
A significant portion of Miami-Dade county has limerock a few inches below the topsoil.  Numerous types of trees have been planted there with only  a few inches of soil.  Usually they use a pickaxe to dig a hole to plant the tree.

Jaboticaba is a fruit tree that has a matte of roots near the surface.
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