Let's consider two issues in turn: what kind of soil, and then how much. The quality of your produce is directly related to the quality of the dirt they grow out of. This makes sense, because plants consist of energy from the sun, oxygen and carbon from the atmosphere, and matter from the soil in which they live. Therefore, it is worth your while to make sure that your beds are full of good dirt. You want to pay attention to a few factors in garden soil, mainly nutrient content and drainage. Once you know what you want, you can buy cheap ingredients and mix them to get what you desire. Base: good ol' dirt A good base for a garden soil mix is the cheap topsoil that you can get at your garden center. Lots of stores sell topsoil for cheap in the spring, like maybe $2 or less for a 40-pound bag. That seems like a lot of dirt, but it's really a negligible amount once you start filling in your bed. Nutrients: compost & peat moss You also want to have a lot of nutrients, so it is a good idea to add in some compost. It's great if you're making it, if not they sell it at garden stores. It's incredibly rich, so it's okay to mix in only a bag or two per raised bed. Peat moss is also a good idea, as it is full of organic matter. It comes in big bags, and is really concentrated so you don't need all that much to have an effect, maybe half a bag for a medium-sized bed. Drainage: sand/vermiculite & peat moss You also need drainage, which refers to the ability of water to seep out of the topsoil. (This is what distinguishes a swamp or marsh from "good" land where you can grow things like tomatoes or corn.) This is aided by little holes in the soil. Since water seeks the lowest level, raised beds inherently have good drainage, but you can make the situation even better. It's a good idea to break up your substrate (the area under your bed) pretty well with a fork or spade before building your bed. You also want to make sure to mix in your added soil with some of your substrate, because an abrupt border can lead to problems with compaction: sometimes roots will never penetrate the substrate if it's not mixed, and drainage will be reduced. It's a good idea to mix some sand into your bed's soil to increase drainage; vermiculite (the white chunks in potting soil) also works, but then it looks too much like potting soil and not enough like a garden for my tastes. The light texture of peat moss can also aid quite a bit in creating better drainage, in addition to the nutrient benefits. That said, it will take a LOT of dirt to fill your raised beds. I built some beds that are 5' wide, 10' long, and 1' high. Each one required a bag of peat moss and 1,600 pounds of topsoil! That's 40 bags of that cheap topsoil, which even at a low price came out to hundreds of dollars for a few beds. I highly recommend against using potting soil or your bill will easily stretch into the thousands of dollars. The way to do it on a budget is to: 1) buy cheap materials 2) mix it yourself 3) use topsoil that is on sale, or maybe even free from a local landfill 4) you can even fill the bottom with straw: a straw bale is pretty cheap and gets you a lot of organic matter. It will biodegrade in a year or two if it's buried at the bottom of your bed, it will increase drainage, it will not hurt your plants, and it's a lot easier to move than dirt. In Scandinavia, they traditionally grow potatoes in straw without even any dirt, and they do fine (plus then they come out totally clean!) 5) don't use potting soil! unless it's old potting soil that you have tossed in your compost pile or something I hope all that helps -- good luck building! Also, it might be a good idea to line the bottom with chicken wire or hardware cloth if you have problems with varmints in your area (so they can't dig up into your bed), or to line the bottom with landscape fabric (to prevent grass etc. from growing up into your bed)

See "D": Empty soda bottles are good space taker uppers, as are bricks/rocks if you want more weight. Packing peanuts are a PITB, and don't offer anything an empty soda bottle doesn't offer, even bricks would be better than peanuts. Water tends to perch above layers like peastone or packing peanuts. And since packing peanuts have closed-cells, they don't hold water or nutrients, and roots can't penetrate beyond any imperfect (open) cells at the very surface of the particles. Soda bottles or bricks at the bottom of the pot take up space in the part of the pot most likely to be occupied by perched water. Essentially, they reduce the volume of soil occupying the PWT, and in doing so, they reduce the amount of perched water the container can hold. This means that air returns to the o/a soil mass much faster. Imagine how much less perched water the soil could hold if up to 90% of the shaded area in figure A above was taken up by bricks or empty soda bottles (90% less). The PWT is always a fixed ht with any given medium, even if it perches atop a drainage layer. Anything you do to reduce the volume of soil in the PWT reduces the volume of perched water. Al

Hey Kimmsr, so, I completed the soil in a jar test, and I was really surprised. Where I thought I had a LOT of OM/compost, turns out there is barely any. I would say it appears to be 1% or less, in a very thin layer floating on the top of the water surface. The rest of the results are harder to tally precisely because the sand and the silt overlap a little at their respective edges, but I can see a general trend. Together, the sand and silt comprise about 70%-75% of the mix. If I had to assign amounts, I'd say it looks like: Clay, 25% Silt 25-30%-ish (depending on overlap with sand) Sand 45-50%-ish (depending on overlap with silt) OM, 1% or less I also did the worm test and was shocked, shocked to find very few worms in the top 12 inches of the soil. I don't know if it's been the freezing weather (last week) or the biblical rainstorms (earlier this week) but I certainly was surprised by the lack of earthworms. The drain test is a little difficult to do right now because we just had a lot of rain, but it appears to be draining faster than 2 hours. So if I'm interpreting these correctly, I am in dire need of more OM, right Kimmsr? I am wondering if the mix that I started (a purchased mix from a reliable local soil company) with was either too light on the OM, or perhaps the OM was not fully composted and the soil food web gobbled it all up? Either way, it sure seems like I need some compost. STAT! And I'm guessing that I WILL need to dig it in rather than just mulch the top. And finally, after reading the PDF you posted earlier, I guess I'm not completely clear on whether to use a fully composted compost---which will provide longer term structure but not much for the soil food web, or a partially composted compost---which will provide more food for the SFW in the short term. help much appreciated! -kmama PS. I guess the issue of whether I need Azomite in this mix is cleared up... there certainly seems to be a rather adequate mineral supply, right? What are your thoughts on Azomite?

Soil-less mediums work best for containers because they maintain viable structure and porosity. Soils and soil based mediums work in the ground because they become part of a much larger system. Once you take real soil out of that system....it no longer functions. Soil-less mediums (potting soils) provide anchorage, plenty of good air spaces (a requirement for germination, rooting, and normal plant development), and available water. Sand, silt, and clay are all of the soil components that work great FOR us in the garden, but AGAINST us in containers. Poking holes with a solid object compacts the soil around the holes. True aeration would remove columns of soil (like a core aerator for lawns). Best to incorporate something that provides nice pore spaces throughout the entire volume within the container. Seeds, also, need oxygen in order to progress properly, as well as moisture. That's why a soil-less medium IS ideal, if you are germinating seeds in containers. Most (so called) germination mixes are made of very finely milled peat moss, along with vermiculite and perlite. Those ingredients work to provide a steady supply of available moisture and oxygen. When I'm germinating seeds, I fill most of the seed flats with a very coarse textured potting medium, followed by a layer of the germination mix. After sowing the seed, I'll cover the seeds (if required) with more of the germination mix and use my misting nozzle to saturate the entire medium. The germinating mix insures that the seeds will have contact with the moisture providing peat. By the time the seedlings have begin to grow a little, their roots enter the highly porous medium.....then LOOK OUT! ;-) My potting mix is made of composted bark fines, peat moss, perlite, coarse granite grit (like for poultry), and Turface.