The Vegetable Garden Soil Mixture
is Crucial to a Good Garden

After building your boxes, the next step is filling them. The vegetable garden soil is very important when doing a Square Foot Garden. Mel mix is comprised of equal parts of three different ingredients. Again, this step is crucial, I know have said this about pretty much every step but with this method you use less of everything so every step become vital to the success of your garden. To be really successful you need to follow each step carefully. That being said lets get into each individual ingredient of the vegetable garden soil mix.

First, we will talk about peat moss. Peat Moss is used to create a light and friable vegetable garden soil while helping with water retention. Peat Moss is considered a non-renewable resource but because the Square Foot Gardening method uses fewer materials and you only use peat moss once, you are using peat moss more responsively then most traditional gardeners do. Most often you will find peat moss in compressed bales, these bales double in volume once you get them open. Our first year when we were setting up our garden we had double the amount of peat moss needed because we didn’t realize that a 3.9 cubic feet bag expanded to 8 cubic feet after we broke it up. We had more soil then we needed to fill our boxes because of the peat moss and since its acidic our soil Ph was off. We still had a crop but some vegetables didn’t do very well. Just remember the peat moss will double in volume when calculating your vegetable garden soil mixture.

Next we have vermiculite, this ingredient has the same job as peat moss. It retains water and keeps the soil loose, which is important for the growth of the vegetables. Vermiculite is made of a porous rock that holds moisture, which your plants can use when they need water. It also helps the soil act like a sponge. It's very hard to over water a Square Foot Garden because of the soil mix. Vermiculite can be hard to find. We found several small bags at different places but it would have been very expensive to get the vermiculite we needed with the small bags. The only place we were able to find the large bags of vermiculite was at garden nurseries. I wouldn’t bother with grocery stores or hardware stores you probably won’t find it there. You could choose to use perlite instead of vermiculite but I wouldn’t. Perlite will float to the top when you water, vermiculite won’t, and if you allow the perlite to dry completely, the wind will blow it away and you will eventually have to replace it. If you absolutely cannot find vermiculite, perlite will work but it’s a pain.

Finally, the blended compost, and I think this is the most important ingredient. This is where your plants will get there nutrients if you don’t have a good blend in your compost your plant will starve. The first two parts of the soil mixture do not really offer any nutritional value so it’s quite important to have good compost. You can do your own soil composting which is discussed on this site as well. It’s easy and since compost is the only ingredient you will have to replace every year, it’s a great way to lessen the garden’s cost. We didn’t start composting until the year we put everything together, so that first year we just bought our compost. We chose to use compost called Gardner & Bloom Harvest Supreme it has seven different ingredients. You need compost with at least five different ingredients so that your plants have all the nutrients they need to grow. Most compost found at hardware stores only have 2 or 3 ingredients so unless you want to mix multiple compost type your self I would start looking at garden nurseries for your vegetable garden soil components. The following year we had our own free compost that we created through out the growing season and it worked great.

Just to give you an idea on what you’ll need to fill a 4x4 foot box 6 inches deep, you’ll need approximately 8 cubic feet of material. Since there are three ingredients you’ll need to divide 8/3=2.66. To make this easier I would do 2.5 cubic feet each of Peat Moss and Vermiculite and then do 3 cubic feet of compost. Again, compost is where your plants get all there nutrients so it’s better to have more compost then anything else but a good vegetable garden soil balance is still very important. This is what it took to fill our boxes:

Vermiculite 3.5 cubic foot bag $28.99

Peat Moss 1 cubic foot bag (expands to 2 cubic foot bag) $8.99

Blended Compost 2 cubic foot bag (two are needed) $8.99

Total soil cost per box (it will be a little different for everyone and a little less if your filling more than one box) $56.00 Now if you’re doing more than one box you can use some of the leftover Vermiculite for the next box and you can get bigger bags of Peat Moss that will be more cost effective. The cool thing is that you only have this expense once. The only thing that has to be replaced each year is the compost. Again, if you do your own composting it’s free to replenish your Vegetable garden soil each year. Over all just make sure you have a good vegetable garden soil mix and I would start out by calling around to see where you can get all the components.


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