Can I Make Compost In The Raised Bed?

ichibandaSeptember 25, 2011

Hi All-

I am now in my second season of vegetable gardening and looking to expand my operation by adding 4 12 foot long, 4 foot wide and 12 inches deep raised vegetable beds.

I am trying to figure out a cheaper way to fill them and wondering if I can fill them with compost. I have priced out using store bought compost, vermiculite, and peat moss or coconut coir fiber but it becomes pretty expensive to fill that many beds. At least 400 or so I think.

I have a shredder and a bunch of palm tree leafs and pine needles as well as grass cuttings each week. I was wondering if I could fill the boxes with these and a bunch of veggie and dinner scraps and compost it all right in the box. Would this work and any ideas on how long it would need to be in their to compost completely? Also in terms of an activator should I put in some compost, or worm tea, or urine or something to get it jump started and composting? Pretty new to compost and have not really done it before so I am not even sure if this would be possible. It would be great if I can do it and it works since I would be using a bunch of stuff from the yard and kitchen that would go into the landfill then. It would save money, clean up my yard and save landfill waste. What do you all think? Would this make a good planting mix and is it possible?

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Compost happens, so what you propose can be done. The link attached might be of some help.

Here is a link that might be useful: Composting Tutorial

    Bookmark   September 25, 2011 at 6:38AM
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I think so...

I am just about to empty much of the soil out of my raised beds and add in grass clippings, dried leaves, and some kitchen scraps. (I also have a compost bin and a compost "pile" but I, like you, would like to do some of the work "in situ".) I figure that if I add a bunch of stuff now, chopped up well, by next spring I should be well on my way to a filled bed. I will supplement with garden soil in the spring, since you really need soil for planting, and not just compost. (I'm not knowledgeable enough to know whether the mixture you describe is adequate for long-term growth but I do know you can't JUST use compost... you'll still need to add in soil.) Keep in mind compost shrinks dramatically from the size of the original pile. But if you keep adding to it while you can, it should work well.

If the raised bed is open to the ground, as they generally are, you really don't need to add anything to get the composting started. Just make sure you've got the right ratio of "browns" to "greens". My "pile" (which is not in a bin) began breaking down very quickly, without turning, when I had a good ratio of dried leaves to grass clippings and kitchen scraps. We got some good rain, but on more dry days, I also watered the pile. It got steaming hot in two a few days.

    Bookmark   September 25, 2011 at 3:23PM
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Oh yeah... you can read all about this online, but as a general rule, you should minimize the amount of pine needles you add to your compost... I've read to use no more than 10% needles, if that much. Some sources say this is just because pine needles break down very slowly, and some say it's because pine needles are very acidic. I don't specifically add pine needles, but they're mixed in with the dried leaves on the floor of my woods, so some do get added.

    Bookmark   September 25, 2011 at 3:26PM
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Many people have the misconception that material to be composted must be in contact with soil so the bacteria that will do the digesting can get to the material, however, all organic matter has on it the wee critters that will convert them to some other form, ie. into compost. Give them close to the right conditions and they will go to work whether there is soil present or not.
Pine needles might be a problem in a compost pile, not because they are acidic, all leaves are that, but the coating on them makes it difficult for the bacteria to digest them. I have not seen a problem with the needles from various evergreens in my compost, as long as I do not make a large layer of them. If they are well mixed with everything else they get digested like everything else.

    Bookmark   September 26, 2011 at 6:40AM
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Your zone location wasn't listed, so difficult to say how long it's going to take for your compost to finish in place.

In my mild climate with a dry 3 months of summer & wet the rest of the year composting in place along with manure takes at least 6 months - 1 year. The only way to get it done faster is to build a huge pile & turn often. I'd say yes to use manure as an activator for your palm & pine needles + lime after the compost is done to balance out the acidic pine. Used coffee grounds can also be part of the mix & are free at St*rbucks. Shredded leaves work great, but do shrink down to about 1/3 or less by spring.

To make it easier on yourself you might try fewer beds with less height. Build one each year for the next few years to create the 4 of them. If you have read the Square Foot Gardening book you can plant more intensely & might not need that much garden.

The volume of your planned beds would take an incredible amount of compost materials to fill + would need additional compost piles outside of the boxes to add to the boxes as needed to fill them up again after composting has happened in the boxes.

Pure compost might work okay for your annual vegetables, but would be better with soil. One of our local garden speakers, Ciscoe Morris suggests 1/3 organic matter to 2/3 soil. Our winter wet cause roots to rot if planted in 100% compost. Though squashes & potatoes grow well in compost piles over summer to harvest in fall.

Can you get soil from the paths or somewhere else on your property? We've heaped up soil from paths onto the planting beds (along with layers of compost materials) then filled paths with mulch material to build mounded raised beds for raspberries, strawberries, rhubarb, & our summer vegetables (cucumbers, squashes, tomatoes, peppers). Fall is a great time of year to build the beds to plant in spring.

When we've built planting beds as you described with a variety of compost materials layered 18-24" high on top of the soil for perennials & shrubs after a year or so the beds are only a about 6" higher than surrounding soil including 2-3" mulch.

Search the vegetable gardening or this site for Jon Hughes postings as he has shown several planting beds using finished compost, but his permanent beds are his special soil mix blended with compost as one ingredient.

Hope that helps~

    Bookmark   September 27, 2011 at 12:32AM
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Many people plant in potting soil, which is peat moss, finely ground bark, or coir, all organic matter with some perlite or vermiculite added to that mix but with no real soil, and their plant grow so why would plants not grow in compost? I have done that for years with good results after it occured to me that those materials were kind of the same thing, except compost was better.
Pat Lanza's Lasagna Garden is almost all organic matter, I have not read where she added soil to the mix she piled on top of soil.
Many years ago people thought that lime needed to be added to compost because of the acidic materials (pine needles) added but research has shown that as the bacteria digest the material (in an aerobic compost pile) the material is adjusted toward neutral and finished compost is very close to neutral, without adding any lime which can slow the digestion process.

    Bookmark   September 27, 2011 at 6:25AM
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toxcrusadr(Zone 6a - MO)

The only potential problem I see, which was alluded to but perhaps not specifically stated, is that compost continues to break down over time, so it will shrink and shrink. Your raised beds will lower themselves. If you want to keep them permanently higher than the surroundings, you'll have to use some soil, which is mainly minerals that will not break down and go away.

You place thin layers of soil in between thicker layers of blended compost ingredients for a great lasagne bed. Say 6" of compost ingredients to 1-2" of soil. You don't even need high quality soil, with all that compost even the worst soil will work fine.

    Bookmark   September 27, 2011 at 3:34PM
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scotty66(8 Hutto TX)

I am doing something very similar to what you proposed... I plan to create 3 new vegetable beds, for the spring, that are each 3'x15'.

In late july I started a compost pile with just lawn clippings and oak leaves (and a few kitchen scraps). Currently it is about 60% done and meaasures 4' x 4'. The next time I mow I plan to start a new pile, so this can "finish" (I'm gessing it can't finish if I keep adding stuff to it).

In craigslist I recently found a nearby source for free manure, and I already have lots of Oak leaves on my property... manure counts as a "green", so that and the leaves should be a good combination for my new pile as well (did I mention I have lots of oak leaves to use up).

I am going to try and keep my new compost piles around 3'x3'... I just need to create the frams for my raised beds and then start my new compost piles inside them them. I noticed under my original pile that the ground looks like it has absorbed lots of nurtients from the compost pile above it... why waste those nutrients in an area i won't be gardening?

By turning the piles every few weeks (or at least once a month) I am hoping to have enough finished compost to fill all my beds with at least 8" - 12". No adding soil will be necessary and I don't plan on tilling the soil either. Just lay that pure and natural compost on top of the dirt and start gardening (the way Mother Nature does it).

I am thinking about adding some "red worms" to my vegetable beds... just for the extra benefits they provide, but I'll wait until spring.

    Bookmark   September 27, 2011 at 9:02PM
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kimmsr... not sure about planting in only compost. I have just read repeatedly (in my "research" about compost) that although people often call compost "dirt" or "soil" it's not, and you must add soil for additional mineral content, rather than growing in only compost. I may be wrong. Also, in lasagna gardening, isn't soil usually added, if for no other reason than to weigh down the layers do they don't blow away?

Compost doesn't HAVE to touch the ground (otherwise those big barrels people have on their sides on rollers wouldn't work) but it's helpful to give access to worms and bugs, etc., which will aid the process. And a lot of people who are using closed barrels add some sort of purchased "compost starter" if they're not using manure, in order to get the process going.

    Bookmark   September 27, 2011 at 10:21PM
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Hi Lizzie,
What you have read in your "research" is all good ;-)

BUTTTTT, there are exceptions and if you are successful in getting your compost going, you can try it out and see if it will work for you (even if it isn't optimum ;-)
I had a lot of extra compost so I piled in on a tarp (just so I could get it out of my bins ,so I could have the bins available to make more).
and then the summer season came upon me ,I decided just to plant in the pile ,instead of letting it just sit there and do nothing, I have harvested hundreds of pounds of Butternut Squash, Watermelons Honeydew Melons and Cantaloupe, and there isn't a single drop of soil in it...
I won't do it again (too hard to get my big trucks by it/ it sucks up half of the driveway, but as our Forum Guinea Pig, I didn't mind showing what could be done ,if one was willing to give it a shot.

    Bookmark   September 27, 2011 at 11:30PM
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scotty66(8 Hutto TX)

@lizzie - as per the book/webpage... soil is NOT one of the ingredients used in a traditional lasagna gardening. many people add it... just because they feel "weird" planting directly into compost.

You can also plant directly into a straw bale with no soil(google straw bale gardening).

Jonhughes has addressed whether or not compost needs soil.

but I would like to know who says "finished" compost isn't "dirt"? what is it then? and what is dirt?

Here is a link that might be useful: lasagna gardening basics

    Bookmark   September 28, 2011 at 12:22AM
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toxcrusadr(Zone 6a - MO)

In my mind dirt or soil is mostly mineral matter, and compost is mostly organic matter.

I use soil in lasagne beds because it's already there, it's in the way, and it's poor quality. I find layering it with compost materials is a great passive way to achieve a nice rich and fluffy raised bed without much work.

There's no real need to grow in 100% compost, but it does work - just ask the volunteer cukes and tomatoes that grow in the compost pile. They are healthier than the ones I coddle in the garden!

    Bookmark   September 28, 2011 at 12:04PM
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Scotty66 - "Dirt" and "soil" are typically used interchangeably. Soil does have an actual definition and an entire science behind it, although I am not all that knowledgeable on the subject, as I mentioned in my first post. But I do know that compost and soil are NOT the same thing, and compost is not the same thing as a mixture of peat moss, coir, and perlite or vermiculite, as another person suggested. Compost (if it's purely compost from kitchen and yard waste) lacks the minerals found in both natural soil AND potting soil. It breaks down to one important element of soil, humus. I didn't really think that things simply *can't* grow in compost only... if that were the case, weeds would never grow on the pile, and I often see that when people have piles they just allow to sit. But, based on what I have read, it's not generally an optimal growing medium. I can grow certain plants in a glass of water, but that doesn't mean that's the optimal medium for their growth. I also don't think that an unamended bale of straw is the best medium for long-term growth of plants. It's definitely not "dirt" even if you can grow in it.

Interesting experiment JH, to prove that things can grow well! I do wonder whether there is a difference between growing solely in compost in a closed container, and growing solely in compost which is sitting on natural soil or crushed rocks, or next to such a surface (to allow for adequate drainage.) Jon's experiment aside, a raised bed filled with compost but open to the ground is different from planting in only compost.

If I had huge amounts of compost and didn't want to spend money to purchase additional soil, then I would probably try to plant in only the compost. But, since that is not the case, I prefer to add soil. In the case of someone wanting to compost in the raised beds... adding soil or some amendments will likely be a necessity, if for no other reason that that compost piles shrink dramatically and it will be difficult to make enough compost in the beds to fill the beds by spring.

    Bookmark   September 29, 2011 at 10:56AM
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Three years ago I moved into this house. I set up raised beds with 2 X 10 lumber, essentially on top of the ground except for a little trenching to get them level. I then chopped up the surface of the topsoil inside the beds. I then began doing what you are proposing, adding compostable materials, letting it rot som, chopping it in with the soil below, etc. The level of the soil inside these beds is up within a couple inches from the top, and I get consistently great gardens growing in them. I've continued to add lots of finished compost regularly and often mulch thickly between plants. I certainly didn't buy anything to fill these beds, and I think it is great.

    Bookmark   September 29, 2011 at 3:59PM
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Hi lizzie_,
You are right on most (if not all) counts, growing in pure compost has a lot of drawbacks, and most of my beds are 25% Clay,25% Pumice, 25% Decomposed Granite and 25% Compost, works like a charm ;-)

But this bed here is like what you proposed, pure compost sitting on Clay, it also works like a charm ;-)

    Bookmark   September 29, 2011 at 5:51PM
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Okay, I believe you. There is no use in disproving my statement, since I don't think I am going to cause the OP to do anything she wouldn't otherwise plan to do. If the OP lives in an area with a real winter (as I do) then I thnk it is unlikely that he/she will, by spring, have enough finished compost to fill his/her raised beds if he/she starts now. (Unless, of course, the beds are extremely shallow.) So, I think he/she will need to add soil or some other amendments, anyway. My statement was not made in an attempt to criticize people who plant in only compost, or deter people from doing so, or anything like that. I have no stake in this! I just know that it takes a LOT to fill even small raised beds (much more than one would imagine when they first construct the beds) and I know compost shrinks, so I think something more than compost will have to be used.

(I also know that you seem to be a master gardener, so I wonder how much luck I would have with some of your set-ups. :-))

    Bookmark   September 29, 2011 at 6:17PM
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Hi Lizzie,
I'm sorry, I meant to harm ;-(

I was agreeing with you, it must have come out wrong...sorry !

BTW.. This is only my third year of trying my hand at gardening, but all the glory goes to God (as it should), I only have 1250 square feet of growing beds and have already donated 7515 lbs of Fresh Veggies to the FoodBank so far this year (since May 1st).
So..Yes , I am blessed, but it isn't because I know any more than anyone else, I am just trying to learn what works and what doesn't.

    Bookmark   September 29, 2011 at 8:39PM
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"Dirt" is the stuff you track into the house and get yelled at for doing.
Soil is the stuff plants grow in and is a combination of the mineral portion and the organic matter. For as long as I can remember people have been doing everything they can to keep organic matter from getting into the soil by catching the grass clippings and throwing them away and where deciduous trees are raking those leaves up every fall and paying someone to haul them away where they pollute the environment so in the spring those people can go the garden center and buy peat moss to replace what they threw away the previous fall.

    Bookmark   September 30, 2011 at 7:05AM
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toxcrusadr(Zone 6a - MO)

kimmsr wrote...

"For as long as I can remember people have been doing everything they can to keep organic matter from getting into the soil by catching the grass clippings and throwing them away and where deciduous trees are raking those leaves up every fall and paying someone to haul them away where they pollute the environment so in the spring those people can go the garden center and buy peat moss to replace what they threw away the previous fall."

...the best run-on sentence summary of what's wrong with the modern American yard that I've ever seen. Kudos!

    Bookmark   September 30, 2011 at 10:35AM
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momovtwo(8 Central TX)

Last fall I started two small (4x2 and 2x2) raised beds made from recycled pallets. As a test to see how well a 'free' garden would do. I started with cardboard and then layered up in 1-2 inch increments, watering each layer as I went... grass clippings, shredded paper, dirt from the yard which is hard icky tasty clay, dried leaves then a few handfuls of coffee grounds and some crushed egg shells. Layered this all the way to the top. Let it rest for a few weeks and then planted them both out with lettuce. They grew just fine all winter, only covered with plastic during our 4 day freeze into the teens. Light frosts I didn't bother. I had lettuce through to the summer heat. The beds did fall to about half full. When the heat sent them into bolt I pulled the plants and mixed the contents. The only thing recognizable was some of the crushed egg shells, everything else had just turned to a nice dark soil. Very pleased for simply the cost of the seed :)
I then added in my own compost as well as some composted manure bringing the mix back to level and planted herbs and peppers. Of all the beds that I have, those two beds have the biggest most productive plants.
I say go for it!!

    Bookmark   September 30, 2011 at 6:00PM
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