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meldabbs

new gardener - help with soil recipe?

meldabbs
12 years ago

I live in central Alabama where we have VERY hot summers. I am planning a raised bed using stacked cinder blocks. I have read that raised beds tend to dry out quicker than standard in ground beds. I also have read that most good loam soils are comprised of at least 50% sand. I am concerned that much sand will dry out too quickly in our summer heat. On the other hand, I do not want to risk soil compaction. I want to find out if a mix of 1/4 organic garden soil, 1/4 peat moss, 1/4 well-composted manure and 1/4 sand sounds reasonable. Thanks, Mel

Comments (8)

  • toxcrusadr
    12 years ago

    Not sure what you mean by 'organic garden soil', this could mean anything from good loam that you already have to a bagged product that is very high in organic matter.

    But, the idea of decreasing the sand is a good one if it is replaced with smaller particles - i.e. silt and/or clay.

    Also keep in mind that peat moss and manure are going to continue to decompose, so making half your mix of those two (or any organic matter) will likely lead to the bed sinking somewhat as it decomposes. As long as you're prepared for that there is nothing wrong with using a lot of compost.

  • meldabbs
    Original Author
    12 years ago

    Thanks Tox. I am using a bagged soil product. In your opinion, will that "sinking" cause a heavy compaction problem?

  • tn_gardening
    12 years ago

    the square foot folks swear by 1/3 vermiculite, 1/3 peat & 1/3 compost

    Maybe it's me and my dealings with clay, but I remember my days at 4-H camp where we'd make pottery out of sand n clay.
    I'd be reluctant to add any sand if you have clay soil.

  • toxcrusadr
    12 years ago

    Not necessarily. Ultimately, the density (compaction) of the soil will depend on: particle size distribution (sand - silt - clay) + organic matter content + foot traffic and probably some other factors.

    tn is right about mixing sand and clay directly, but you didn't say you were adding anything to existing soil, but instead looking for a recipe for raised beds. I am curious what your native soil is like that you'll be building on top of.

    I think your blend sounds OK. I generally avoid peat moss and vermiculite but only because in my area it's imported from somewhere else and I'd rather use local materials. OTOH my garden isn't the most fabulous, maybe I should use 'em. :-]

  • meldabbs
    Original Author
    12 years ago

    LOL Tox. We have ridiculously hard red clay here. You are right, I decided not to attempt to break any of that up - maybe next year. I've simply dry stacked cement blocks 2 high. I'm actually a funny girl. I posted this question and then proceeded to go outside and mix the 1/4-1/4-1/4-1/4 mix I first mentioned. I've now got the bed filled roughly half way. It seems "loamy" enough :o) We'll just have to see. To fill it up, I think maybe I will incorporate a 1/3 each mix of sand, manure and the bagged soil. And I do intend to test in a couple of weeks and amend accordingly.

  • tishtoshnm Zone 6/NM
    12 years ago

    I would consider adding some of your clay to the mix. I live in a mountain desert and our summers are also quite dry. I found the square foot garden mix to dry out much too fast. One nice thing about clay, once it is wet, it does hold water well. If you let it dry out too much though, it will repel water. I moved away from SFG and now just amend my clay heavily with compost, peat and then I add vermiculite to each planting hole.

  • joeworm
    12 years ago

    my raised bed consists of 1/3 topsoil, 1/3 pine fines ( 1/2" screened), and 1/3 composted manure also added lime to raise the PH. topsoil and pine fines are acid. all of my plants are healthy and insect free. the topsoil i dug out of the woods nearby, the compost i made myself, the pine fines i bought in cy bulk, an overall good inexpensive mix.

  • Kimmsr
    12 years ago

    Loam is a specific soil type composed of about 45 percent sand, 25 percent silt, 25 percent clay and 5 percent organic matter. You can find clay loam, sandy loam, silty loam, and maybe some others. Loam is not very widespread. There are some places that put together a soil mix that approximates loam but some soil scientists do not think you can make loam, only closely approximate it.
    The best way to make a soil that does not dry out really quickly is to add organic matter to any soil type because that vegetative waste will help hold moisture.