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valleymagpie

How do I amend decomposed granite?

17 years ago

Hi all,

Never been on the garden forum before, but have gotten so much good advice from the home forums I thought I'd submit this query for your help.

In Southern Oregon, zone 8. with decomposted granite "soil." Every time I want to plant a little something I have to use a pick! Our home is new and we have to landscape. How should I amend the soil?

Thanks,

Magpie

Comments (10)

  • 17 years ago

    Hi Mag,

    Rather than breaking your back trying to jackhammer through all that rock, perhaps you should consider raised beds with some nice imported soil.

    Dan

    Here is a link that might be useful: My raised beds constructed this month.

  • 17 years ago

    Dan,

    Great suggestion! We are doing that where it is practical but the nature of the yard does not permit raised beds everywhere. Sorry I can't see your raised beds, I'm not on Facebook.

    -Magpie

  • 17 years ago

    Can you get in a few truckloads of good topsoil and cut it 4:1 with compost? Check for reliable sources among nurseries and gardeners in your area.

  • 17 years ago

    This area is decomposed granite as well.

    I'm always on the lookout for organic matter. After the October 2007 wildfire, I saw a fellow chipping palm fronds on my way to town one morning. I did a quick u-turn to stop and ask if he had a place to dump. He delivered approximately 30 cubic yards of material that I used as part of erosion control contours along the steep slopes that had burned, as well as for mulch to cover pathways.

    I killed my pickup hauling load after load of whatever type of manure that I could find free for the hauling. After awhile, you will be able to spot a secluded manure pile while driving at 50 MPH on the road to town to do errands. I have yet to have the owner of such abundance turn me down when I asked for permission to haul it away.

    Terran

  • 17 years ago

    The best thing to amend your soil, any soil, organic matter, compost, leaf mold, what ever organic matter you can get. Any "topsoil" you get will be about 95 percent what you already have, the mineral portion of the soil and maybe about 5 percent organic matter. Spend your money on what will really help your soil, organic matter.
    Based on all the trees I saw in Oregon getting tree leaves should not be a problem.

  • 17 years ago

    Thank you everybody!

    Sorry for not replying sooner, I've been out of the area. Kimmsr, good suggestion. It is true that decomposed granite is used widely as a soil amendment itself. I'll go for the organic matter. We do have lots of trees and leaves.

    dchall, I don't understand. Our house is on a slab dug 3 feet down. Our lot is a "stairstep;" slope up on the west side and rather abrupt 12-ft "cliff" down on the east side. Builders were diligent with drains around the house. I'm not in the part of Oregon with rain all year but can have heavy rain in the winter/spring. Why would amending the soil bring on drainage problems?

    - Magpie

  • 10 years ago

    Hi everybody. I know this is an outdated subject. have been dog research all day because we too are on a small property with mostly DG. recently I did a bunch of excavation work to make the areas around the house more usable. In turn have a lot of DG sand to amend. I took a 3' x 300' bed and turned it into a 10' x 300' bed with an extra 2' of DG as topsoil. My plans are to amend strictly with organic matter. All organic matter decomposes into humates that plants can uptake. Sand is super important in soil but also is organic matter, micro-organisms feed off of the organic matter as well as the sand to break it down into usable micro-nutrients.

    I would recommend if growing in DG to amend with compost, mulch, horse, alpaca, chicken, steer, goat, or any other manure that is fairly dry. DG has lots of potassium and lots of silica, so your plants will not need any of that. Due to the time constraints of making your own soil. I would suggest amending year after year until you get the dark hummis filled consistency your are looking for. Also make sure you keep it up year after year with the carbon amending. Or if you are looking for something long term look into BioChar. It is a great sustainable carbon source for soil.


    Thanks Veda

  • 6 years ago

    Does anyone know how to remove a section of DG in a newly made DG patio ? I want to create movement and interest and what I have now is a huge blank area. There isn’t any advice about breaking up DG when I google it. I want to create a berm for planting like in this pic. Any advice appreciated.

  • 6 years ago

    So is it mostly rock then? Fairly solid? Not soil you can just scoop up? I would use a pick-mattock. It gives you a pointy end to break up stubborn material, and a flat blade end when it's not quite as stubborn and you can break up more at a time. I bought one from easydigging.com, this guy assembles them by hand using extra long handles so you don't have to stoop over to hit the ground. Tool makers often skimp on the handle, but it's critical for heavy work.

    I actually don't see the pick mattock on the website now, I sent them an email to see if they still have em or not. They do have a bunch of other tools like grub hoes and the like that might work depending on how tough your DG is. They also have charts where you can look up a task and find a tool. No affiliation, just a happy customer. It's been a great tool for the hard clay I have, and for getting rocks out.

    Post a pic of the ground if you can.