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joe1980_gw

Making soil for new raised veggie bed

14 years ago

I'm planning to make a 4'x16'x1' raised bed, which will set atop about 6 to 8" of decent topsoil, which is on top of cruddy clay soil. It'll be on the top edge of a hill, so I don't think drainage will be any kind of issue. Anyways, I currently grow in containers, using Al's 5-1-1 mix for veggies, and Al's gritty mix for other non-food plants. From what I understand, I should not start digging into the cruddy clay, but rather just leave it, and build new soil on top.

With that said, I need to mix up some good quality soil for my raised bed. I'm wondering if it'd be beneficial to use some of the ingredients of the 5-1-1 and/or the gritty mix. Obviously the gritty mix in it's entirety wouldn't work, but I'm wondering if the turface or napa floor dry would be a beneficial ingredient. Also, I am thinking that pine bark fines would be a good thing to add, to bring the pH down to favorable levels. I plan to build a compost bin, but currently have no compost to add. So, what would be the best mixture to make to fill my raised bed to start? Or am I best off looking for plain old topsoil? I plan to start using this bed next year, so I have a bit of time on my side to get the soil ready, let it sit & fester, as well as build up some compost this fall with leaves and yard waste like my spent veggie plants from this year, and cut down perennials. I also figure to toss my used 5-1-1 mix and used MG from the containers into my raised bed as well. Thanks in advance!

Joe

Comments (11)

  • 14 years ago

    "Topsoil" is a meaningless term since it is simply the top 4 to 6 inches of soil from someplace. Get in your mind what you want when purchasing any soil and try to find that. For that raised bed I would want a soil that was about 45 percent sand, 25 percent silt, 25 percent clay, and about 5 percent organic matter. Once that soil is in place then you need to keep adding organic matter keeping the humus level in that soil between 5 and 8 percent.
    To determine how well your native soil drains dig a hole about 1 foot in diameter and 1 foot deep and fill it with water. After that drains refill it and time how long it takes the second filling to drain out. Less then about 2 hours and it drains too quickly and if it takes more then about 6 hours it may drain too slowly.

  • 14 years ago

    A while ago Al mentioned in a thread (link below) how he made a mix for raised beds. It is very nice.

    In my experience with raised beds over my top soil I have not noticed much difference with 6 or 12 inch beds - could be something to look into with all that volume - or build upward over time. For my raised beds I like to rob the soil from where I am leveling an area (I garden on a hill, uphill seems to be best) or from a pathway and mix with as much compost as I think it needs.

    The gardens/beds that I have made always improve with time and effort. I do think that spending money upfront can get you off to a faster start but I don't think that there is much of a substitute for time and management. I have not had luck with planting in bulk soil - 2x - shame on me, that could be just my luck or local conditions though.
    I have been meaning to try turface in a raised bed (probably a small one), I already mix in 5-1-1 and other potting mix when it is finished. Of the ingredients of the 5-1-1 if I were adding them fresh I would leave out the perlite, it is too expensive and I think it degrades in the soil (unlike the turface).
    Hope this helps. Best of luck!

    Here is a link that might be useful: http://forums2.gardenweb.com/forums/load/contain/msg0306520029215.html

  • 14 years ago

    There's enough help on the web to suggest to any home gardener what consitutes the proper soil for the particular vegetable or plant one is putting into the ground.
    Its not necessary to improve some soil for some vegetables....lettuce for example. It has such a short harvest time it cant possibly use any fertilizer it is given, nor any 'improved' soil that is used in place of.
    Instead of trying to improve 'all', find out what kind of soil the chosen vegetables prefer and pick something in the middle.

    Going overboard on what somebody has suggested as being 'good' is a great way to never see the vegetables see the light of day.
    Vegetables are grown very well in the natural soil that surrounds you. Often it only needs a little help or none whatsoever to come to something fruitful.

  • 14 years ago

    Use what you have + purchased compost to fill beds to within 1" of edge. I've also mixed in used coffee grounds in small amounts & works fine in my climate.

    Adding a complete organic fertilizer will give your vegs all they need.

  • 14 years ago

    I've hit the jackpot today. I decided to investigate the area I plan to make a garden in, just to make sure what kind of soil is in THAT spot. The rest of the yard is 6 to 8" of good topsoil, on top of clay. I know this from when I plented trees. Anyways, I thought to myself "ya know, I've never really planted any trees there, and thus never actually did any digging". So, I grabbed my shovel, and started digging. I got down about 18" and did not hit any clay yet. It was literally ALL crisp dark topsoil. I am pretty excited now, because I can stop worrying about the cost, and start worrying about making my garden.

    So, now I will be going with a standard ole in-ground garden. Should I still build an edge? I would imagine I am going to want to try & supress the grass from growing into the garden somehow, and also need some sort of foundation to mount a rabbit fence. I also plan to add in a decent amount of compost. Any pointers?

    Joe

  • 14 years ago

    What to do to keep that grass from encroaching into the garden will depend on what type of grass you have. Many typical turf grasses will spread out with rhizomes that are fairly hear the surface and almost any edging material will work to keep those grasses out. Things like Quack Grass and Johnston Grass also spread by rhizomes that grow deeper so yo would need a barrier that goes 10 inches or so into the soil to keep them out.
    Some grasses are wimpy enough growers that tilling them in, or covering them with newspaper, is enough to kill them in the garden area, but grasses like Quack Grass and Johnston Grass will sprout from any wee bit of the rhizome left behind.
    For Quack Grass I use 10 inch alumnum flashing, rolling the edge that will be about ground level so I don't slice myself, and then often put some edging blocks down to give me something to put the lawn mower wheels on as I cut around that bed. Janet Macunovich (Caring For Perennials) uses plastic carpet runner.

  • 14 years ago

    >>For that raised bed I would want a soil that was about 45 percent sand, 25 percent silt, 25 percent clay, and about 5 percent organic matter. Once that soil is in place then you need to keep adding organic matter keeping the humus level in that soil between 5 and 8 percent.

    What kind of sand can you buy in bulk, by the yard, to use?

    Where can you get silt, what exactly is silt?, and clay, is this a special clay for gardens?, in bulk?

    Thanks

  • 14 years ago

    There is what is called builders sand and then there is sandbox sand or sometimes play yard sand, or there is just sand. There is also foundry sand and filter sand although those are not too readily available.

  • 14 years ago

    So any kind of sand will do??

    What about the silt and clay? Is there a particular type of clay? We don't have much clay here in Florida that I know of.

    Where might I get those in bulk?

    Thanks

  • 14 years ago

    You are looking for coarse or builders sand. The sand you want for your soil has rough broken edges. Play sand, beach sand, etc have rounded edges.

  • 14 years ago

    Regarding keeping grass out: I wound up needing a fair-sized border around the outside of my deer fencing. I use books of straw bales all around and keep it refreshed each year. I tuck it close to the fence inside and out. Works pretty well, although I'm still hauling out hunks of grass on the border here and there.