This year, I challenged myself to fill our raised garden beds for under $20. Last year, we used Mel's mix to fill our two raised beds and vowed to find a less expensive way for the future. For those who do not know, Mel's mix is a great solution for square foot gardening. It consists of one part compost, one part peat, and one part vermiculite. The only issue with this mix is if you want to do this on a larger scale or with larger raised beds you will spend more money filling the beds than you will recoup over your first few years or gardening! The biggest issue we had was finding a good source of the vermiculite and had to order it online. We also sourced the rest of the fill from local big box stores and bought everything by the bag. All in all this turned out to be over $60-70 per bed that we filled and was way more than we were willing to spend. We knew that this year we needed a better solution and I hope we have found it! I spent a lot of time trying different mixes researching different options and this is what I came up with.
There are three main components of a good raised bed or gardening soil. The first is nutrients, you have to have a good base of nutrient rich soil. In our case we are using a composted manure for the majority and will also amend throughout the year with worm castings and our backyard compost. This provides all of the N-P-K macronutrients as well as the micro nutrients needed for most plants to thrive. Compost is available from local farms, big box stores by the bag, and free if you have your own compost pile!
The second component is something to allow the soil to retain water and also provide aeration to the soil. In our case we are using Spagnum peat moss to fulfill this need. Peat is one of the best things for retaining water and nutrients as well as providing aeration for the soil and roots. This helps to prevent the compost from clinging together and drying out and also provides needed air the roots of the plants. The peat moss was the most expensive part of the mix but since we aren't using that much we were able to still get some benefits of the peat without breaking the bank.
The last main components is something to provide drainage. In my case I chose to use sand because it is locally available, cheap, and does a great job at keep the soil loose and allowing water to drain through. You can get sand from any landscape supply for the best price or by it in bags just about anywhere.
The ratio that I chose to use is 60-70% Compost, 15-20% peat, and 15-20% sand. This gave me a nutrient rich soil that is light and fluffy, does not compact, and holds moisture very well. Only this years growing season will tell the full story of how well this works out for us, but just working with this soil over the past week has me with high hopes.
The total estimated cost for the this soil mix was approximately $ .92 per cubic foot. For our 3' x 6' beds it cost us around $14.00 to fill each bed. This is just an estimate and your costs will vary depending on time of year and how you are able to source the sand and compost. This is a huge leap in the right direction for us as we are expanding our small homestead gardening operation this year by quite a bit. With plans to double our gardens again next year this soil mix has the potential to save us a lot of money and provide excellent soil for our gardens!
