Without a soil test of your native soil, or of the purchased soil, you won't truly know what additions you need, but a good rough guide would be to add 1 bag of compost to each 8 bags of topsoil. This is assuming that the "Compost" doesn't already have a large amount of soil in it - often there is. In that case, composted manure would be a better choice.

If you want to be strictly organic, you should look for that certification on the label. Without that label, you won't know if it is truly organic or not. This raises the question of why you want to have an organic garden, because it generally necessitates more labor and more involvement in the process of creating and maintaining healthy soil.

There are organic pesticides and herbicides, just as it is possible to have non-organic compost. The definition is complex, but a simplified one would be that an organic garden relies on natural inputs and systems to create a healthy soil that supports growing healthy plants without the addition of man-made, short-term synthetic solutions.

"Top soil" can encompass a lot of variables, it may have some organic matter already in it, or it may be a mix of sand, silt, and clay, in almost any number of different ratios, with no organic material at all. It may be sterile, or full of weed seeds, or even contaminated. Unless it is labeled, you won't know - but we take these kinds of chances every day when we buy anything.

I suspect that the mushroom compost would be the most affordable thing in your area, and it is generally a very beneficial addition. OMRI lists mushroom compost as acceptable UNLESS it contains uncomposted animal manures, in which it is Disallowed for food crops for human consumption. If your crops won't be harvested for at least 120 days, even mushroom compost with animal manures is permitted. If you can buy it in bulk (most of it comes from PA) it should be very affordable.

In the meantime, it might be helpful for you to wade though some of the threads on this forum about why people choose to grow organically and what advantages "synthetic" gardening can provide. Many new gardeners end up with a hybrid of the two, but it is entirely possible to start organic and succeed. You just have to understand the limitations and possibilities.

I would just go to a local, reputable construction yard and look the stuff over and have a truckfull delivered. There's no guarantee that the soils you buy will be absolutely chemical-free, but the same is true of anything you bring in. :)

To add to what bi11me said, I'd get it by the pickup load instead of from bags at a big box store. I don't know what size your bed are going to be, but, a 40 pound bag won't go too far. I'd also look for my own source of organic material to make compost. Leaves in fall; lawn clippings from lawns not treated with weed and feed products in spring, summer, and fall; kitchen waste.

Everyone-

Thank you all for your input, I appreciate the help. After considering all of the options, it sounds like my best option is to buy soil that is already mixed with some level of compost matter then begin to add my own organic compost to it going forward. I will plan on visiting my local nursery this weekend to get the best mix available.

Thanks again,
Michael

I have had bad experiences with what garden centers call topsoil. It is screen and almost powdery. It had very little organic matter. I later learned that it is the ideal choice for landscaping projects that involve setting stones in the ground or changing levels, it's not for growing vegetables, unless amended.

billme & kimmsr said it best.
Because you never know for sure what you are getting in a store bought mix.
You should start a compost pile as soon as you have time (IMO).

Have you done a google search to see if there is someone in your area who delivers quality garden soil, not just top soil? I have a company that delivers garden soil that has composted horse manure and I'm not really sure what else. It's great stuff and only $32 a yd and the minimum is just 4 yds. with no delivery fee. It would be a lot cheaper if you could buy it in bulk rather than by the bag. You'll need a lot of bags.

We just set up new beds on our new property so no way could we afford the bags. Our native soil here is packed down from the equipment, etc. and nothing but grass can grow in this stuff right now. 4 yds. worked out just right for us.

I just ordered some topsoil for raised beds. My options in the area seem to be either topsoil or loam (though whether it is really, strictly "loam" I don't know), or those things mixed 50/50 with compost.

The 50/50 compost blend sounds attractive, but I've had trouble before when I filled raised beds with too high a percentage of organic matter, since the organic matter gets consumed, and the level sinks so much over time. This is especially a problem with perennial beds.

Ultimately, I chose to get the plain old topsoil (or maybe the place I got it from called it loam), and I will amend it myself as I see fit. I've had great success amending my native soil and my other raised beds, so I'm sure it will be fine.

Topsoil from unknown sources sometimes has weed seeds, so I like to fill the containers and level it out and water it good, then wait for weed seeds to sprout. Scratch up the surface good without tilling too deep will kill off the first crop of weeds. Sometimes I do it twice before setting any plants out.

Hello. I was wondering what you ended up doing, & how it worked out for you? I'm in the process of building a raised garden bed. I am so overwhelmed & confused by what organic soil to purchase to go in it.

deerbones, what you want to fill that garden bed is a soil composed of about 45 percent sand, 45 percent clay, and 10 percent organic matter. Silt is somewhat difficult to get these days, or at least uncontaminated silt. I have found, on occasion, bagged "topsoil" that comes close to that I just described but it takes careful looking. If a landscape business sells soil in bulk ask about getting a 1 cup sample to test and use this test to see if it comes close to what you need.

Soil test for organic
material. 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.

Thank you very much! Great information.

deerbones: there's a Chinese saying "No bad soil". This means that any soil can be improved. I would concentrate on improving your native soil without purchasing someone else's. An inch of compost every year is a good start, especially if it's yoiur own compost, i.e. retained fertility. Growing legumes in rotation is next; that will give you all the nitrogen you need in time - no quick fix here. Winter cover crops next to give you more live carbon. Then a soil test so you can limit yourself to supplying those minerals that are defficient without adding to those that are ok - balance is everything. Go for the major minerals first, then the minor minerals later once the major ones are in balance. By the way, I never understood why people have raised beds. I find that loosening the soil will result in raised-beds-without-bordres - "crowned" beds, if you like, that will eventually give you loose soil to a depth of 18 inches or more. Regards, Peter.

True that there "is no bad soil" but if one is starting from scratch why not start with the best you can rather than any soil that may not be the best?

Raised beds may be necessary where someone has soil that does not drain well and does not want to wait years for that soil to be corrected by adding organic matter. There are good reasons, peter, for raised beds.

kimmq is kiommsr

LOL!! Does Tim deliver outside of the Phoenix area? This info is not specifically helpful to anyone living outside that location but it does reinforce the notion that bulk soil products are available just about anywhere. Different suppliers will offer different soil 'formulations' and most will work perfectly well for any raised bed gardening with the addition of any necessary organic matter (if not already incorporated into the soil mix). But it is always worth confirming the quality of the product before purchasing with a visual inspection/evaluation.

This might work for you http://www.amazon.com/

merjisa
surely you jest -- unless you found other than I. They are currently offering either miracle grow (will never be used in a garden for foods I intend to consume) or from a wide selection of one; as far as "100% cert organic" (I like that, just not critical for this project) at nearly 15 bucks for a 4 quart bag!

I only looked at Amazon Prime.