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devin_mendoza

Premade Raised Bed soil - is this mix ideal?

Devin Mendoza
9 years ago

Hello,

I've decided to go with raised beds after a good bit of reading on here. I will be growing mainly tomatoes and a small variety of other veggies. (6) 3'x6'x14" beds.

Now, I wanted to try and make the ideal loam with 5-10% organic matter but I'm pretty much limited to what I can haul around in my 5 ft truck bed.

There is a local Living Earth a few minutes from home that sells a premade mix that is:

'Planting Mix For building planting beds, our Planting Mix is blended from our finest materials, including compost, screened mulch and sand. This material is ready to use and designed to build the raised beds found in many landscapes. Planting Mix drains well, yet retains the moisture plants need.'

I don't know the ratios yet but it's a good bit different that the plan of Loam+OM.

Thoughts? Should I try their mix or make my own from what they have?

They also sell topsoil and several grades of sand, as well as compost. I can source a couple of different bagged composts (composted cow manure, mushroom compost, Living Earth compost, and a Tri-mix with mushroom/horse manure/wood compost.)

This post was edited by DevinM on Tue, Dec 23, 14 at 16:50

Comments (13)

  • grubby_AZ Tucson Z9
    9 years ago

    What are you starting with? Is it so bad you want to ignore it completely and will be dumping the new $tuff on top and not mixing them at all?

    Also be aware that there is NO common definition for "topsoil".

  • PKponder TX Z7B
    9 years ago

    I've used a 40/60 mix of compost and sandy loam from Living Earth to build raised beds on limestone ledge and I had huge crops of tomatoes, squash, peppers and ornamentals also. Well worth the $125. for 5 yards delivered.

    It was a lot of work with the wheelbarrow, so remember to pace yourself :-)

  • Devin Mendoza
    Original Author
    9 years ago

    Grubby-

    I haven't soil tested what I have, nor put any in a jar with water to ballpark a ratio, but there's alot of clay and drainage is pretty poor in the yard (probably has alot to do with no gutters and a small backyard). I had only planned to remove the St. Aug and put about 12" of a planting mix (or mix my own) on top.

    Yes I know topsoil varies, they claim it's sandy loam but I'd need to check it via the jar/water method.

    PK- glad to know you've had success with their soil!

  • Kimmsr
    9 years ago

    First be aware that it it difficult for you to make Loam. While you may copy the mix that makes Loam it takes Ma Nature to actually make it. The linked definition of what is loam, from Purdue, is one of the best I have seen.
    If possible get a 1 cup sample of the soil that company is selling and test it,
    1) Soil test for organic matter. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. For example, a good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.
    to see what it really looks like. Mostly you are interested in the amount of organic matter, not so much the ratio of the mineral portion of that soil.

    Here is a link that might be useful: What is loam

  • PKponder TX Z7B
    9 years ago

    DevinM, not sure if you have the black gumbo clay that is common in the Houston area, that stuff is very fertile, just hard to work with until you get it amended. Some of the best St Augustine sod is grown down there.

  • toxcrusadr
    9 years ago

    That mix does not sound that great to me for two reasons.

    If the only mineral (soil) component is sand, it's going to be VERY porous and drain very fast in a raised bed. I would prefer more of a balanced sand/silt/clay type soil, mixed with compost.

    Second, if the amount of compost they are adding is very high (say over 1/3 of the volume), it will continue to decompose and the bed will sink down. Plus there is a natural fluff just from processing it that will compact down more rapidly than the shrinkage from decomposition. This is not a problem as long as you plan for it - i.e. pile it up higher than the final desired height or be ready to add more soil next year.

    Break up the native soil surface underneath before you add it so the layers will intermix a bit better and plant roots can find their way in.

  • Devin Mendoza
    Original Author
    9 years ago

    Thanks for the advice guys. I'm going to do what I should have done and send out a soil sample to see if I can have success planting in ground. It would be alot cheaper if I can do that!

    Pk- The soil is black and orange, i'll post pics when I pull the samples.

    ***Is A&M a good place to send for the soil sample?***

    I was thinking:

    "1. Routine Analysis (R) $10 per sample
    (pH, NO3-N, Conductivity and Mehlich III by ICP P, K, Ca, Mg, Na, and S)
    OR
    9. R + Organic Matter (OM) $30 per sample
    (In addition to suite 1, adds organic matter test)"

    This post was edited by DevinM on Tue, Dec 23, 14 at 17:14

  • nancyjane_gardener
    9 years ago

    What I have done when creating new beds (we did about 1-2 per year) in HEAVY clay soil, is to fork and break up as much as possible, mixing in composted Horse Manure, watering it in as much as possible. We only have a 2 week window for tilling spring and fall. Then some garden mix from an organic place,water it in as well.We then lay down the frames lined with hardware cloth, and fill with the organic garden mix from the landfill (about $14 per yard) . We water it in pretty well for the settling, top it off, water it again and we're ready for planting! Seems to work for us! Nancy

  • Devin Mendoza
    Original Author
    9 years ago

    Edit: **Should I make a new thread?**

    So this thread has definitely turned my idea of raised beds upside down.. I'm going to send out a soil sample asap, but all this in ground reading is alot to catch up since I was set on raised beds.

    I am reading opposing ideas on removing the lawn vs pulling and flipping it vs smothering it... I planned to plant in mid to late February, so not alot of time! (No round up will be used.)

    I think i'd still like to do a "short raised bed" to hold ~2" of compost and ~3" of mulch. (This would depend on the soil analysis.)

    Turn the soil (with shovel) or leave it or fork it or till it?! So many opinions!

    I plan on keeping it organic and not having to resort to bagged organic fertilizer, but instead use a variety of composts and meals (again the soil test will affect this.)

    List of things to be grown:
    Tomatoes
    Peppers
    Carrots
    Collards
    Lettuce
    Melons
    Cucumbers
    Thyme
    Cilantro

    Thanks in advance

  • toxcrusadr
    9 years ago

    I think a short raised bed is a good idea for clay, this is what I have. I didn't really set out to make raised beds, but in the process of adding compost, a few bags of topsoil, discarded sandbags, etc. over several years, there is not only more 'stuff' there but the soil has fluffed and become less compacted. The end result is 4-6" higher ground. At some point I started putting borders around the beds to keep that in. It's a gradual process, a bit different from building foot-tall boxes and filling with purchased soil all at once.

    Many clay soils are fertile (clay has a lot of exchange sites for nutrients to hang onto, for example), but the texture is the problem, leading to issues with drainage, compaction etc. So the fluffing over time approach works pretty well. Sure is cheaper than building high raised beds AND paying to fill them all at once. It takes some patience.

    A&M sounds like a perfectly fine place to have a soil test done. An extra $20 is a lot for an organic matter test, and you probably already know it's lower than you would want, right? So you might be able to save some $ there. OTOH it's not all that much, and if you amend for a few years and test again, you'll know how much improvement there is.

  • Kimmsr
    9 years ago

    You will find a lot of disagreement about whether sod needs to be removed or not, but if you plan on putting a raised bed, 6 plus inches, over the sod there is no need to remove it since the raised bed will smother the grass. On the other hand I have created numerous ground level planting beds simply by covering the existing sod with newspaper/cardboard and covering that with shredded leaves and that has killed the grass growing there and left the soil in a very good workable condition.
    There is nothing wrong with clay that adequate amounts of organic matter will not help, in time.
    Texas A & M does a good job of soil testing, and you have the added benefit of having a resource readily available to answer questions from both the horticulturist and maybe Master Gardeners. Visit the campus and you will find there are demonstration and trail gardens, not just farm studies.
    In addition to the soil tests done by Texas A & M you might want to dig in with these simple soil tests,
    1) Soil test for organic matter. From that soil sample put enough of the rest to make a 4 inch level in a clear 1 quart jar, with a tight fitting lid. Fill that jar with water and replace the lid, tightly. Shake the jar vigorously and then let it stand for 24 hours. Your soil will settle out according to soil particle size and weight. For example, a good loam will have about 1-3/4 inch (about 45%) of sand on the bottom. about 1 inch (about 25%) of silt next, about 1 inch (25%) of clay above that, and about 1/4 inch (about 5%) of organic matter on the top.

    2) Drainage. Dig a hole 1 foot square and 1 foot deep and fill that with water. After that water drains away refill the hole with more water and time how long it takes that to drain away. Anything less than 2 hours and your soil drainsâ too quickly and needs more organic matter to slow that drainage down. Anything over 6 hours and the soil drains too slowly and needs lots of organic matter to speed it up.

    3) Tilth. Take a handful of your slightly damp soil and squeeze it tightly. When the pressure is released the soil should hold together in that clump, but when poked with a finger that clump should fall apart.

    4) Smell. What does your soil smell like? A pleasant, rich earthy odor? Putrid, offensive, repugnant odor? The more organic matter in your soil the more active the soil bacteria will be and the nicer your soil will smell, to9 a point. Too much organic matter can be bad as well.

    5) Life. How many earthworms per shovel full were there? 5 or more indicates a pretty healthy soil. Fewer than 5, according to the Natural Resources Conservation Service, indicates a soil that is not healthy.

    to see what your soil looks like.

  • toxcrusadr
    9 years ago

    If you get that soil test, ask them if the report will have recommendations for amendments for any deficient nutrients. They almost always recommend N fertilizer, which most of us ignore since compost has plenty of it, but for things like pH adjustment or less seasonable variable nutrients like P and K, it's handy to have those lb/1000 sq ft recommendations done for you.

  • Devin Mendoza
    Original Author
    9 years ago

    Thanks for the advice guys, its very much appreciated! I will post an update later and hopefully this will be a successful start to in ground planting!

    God bless and Happy New Year!!!

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