How To: Square Foot Gardening Soil

When I started my garden last year I went out to a local company and picked up 1 cubic yard of soil. It was what they called Ultra Soil, which is perfect for raised beds. I did not like the quality of the soil, it was full of clay, so I added peat moss and compost to it in hopes it would improve the quality. Needless to say my garden did not survive and I blame it mostly on the soil conditions.

When I started planning my garden this spring I knew I had to assess my soil situation. I looked everywhere for good quality soil that I could buy in bulk but ended up empty handed. I remembered a book I saw that explained how to make my own soil after having a conversation with my friend Nicole. Her husband's garden is beautiful and they have a great harvest each year.

Making your own soil is not difficult but it is labor intensive and you may have to go to a couple of nurseries to find the different components at a decent price. I must say that choosing to make my own soil was the best decision I have ever made for my garden. My plants have thrived and grown beautifully however I have a gang of squirrel bandits that have literally eaten most of my harvest. That's a another story for another time.

The Soil
Square foot gardening soil is often referred to as Mel's Mix. Mel Bartholomew is the author behind the popular All New Square Foot Gardening. There are only three components to this soil. Compost, peat moss and vermiculite.

Compost provides the nutrients your plants need to grow and flourish. A good compost contains 3 to 5 different sources. Each source benefits your plants differently. I found out that lobster compost is very beneficial to tomato plants. There are many different sources of compost like cow manure, poultry manure, coffee grounds, wood chips, leaves, worm castings, and many others. Blending 3 to 5 different sources of compost will aid in a more balance compost that will benefit your plants.

Vermiculite is a natural mineral. It has many uses but for us it is a soil conditioner. It helps keep the soil light, allowing for good air flow and aids in absorbing and retaining water. Vermiculite is available in many grades, for soil you should use the course grade. Peat moss is also a soil conditioner. It regulates the moisture and air around plant roots.

The Recipe

Equal parts compost, peat moss and vermiculite

1/3 vermiculite
1/3 peat moss
1/3 compost mix | I used a blend of cow manure, worm castings and mushroom compost

This is done by volume. The amount of soil you need depends on the size of your raised planter bed. The SFG method only requires 6" of soil. If you have a standard bed that is 4' x 4' x 6" you will need 8 cu. ft. of soil mix. The equation is L x W x 0.5 = ___cu. ft.

In my case I needed 16 cu. ft of soil mix (8 x 4 x 0.5). My beds are 12" deep and since it isn't necessary to have more than 6" of soil mix, I kept most of my previous soil intact and only removed what I didn't need. This also keeps the cost down.

Once you have calculated the amount of soil needed, divide that number by 3 and you will have the amount of each component needed to make your soil.

Mix It Up

In addition to your components you will need a tarp | wheelbarrow | 5 gallon bucket

In a large wheelbarrow, mix together your different sources of compost.  Remember a good compost is made up of 3 to 5 different sources.

On a large tarp, add equal parts each of vermiculite, peat moss and compost mix. Do not add all 8 or 16 cu. ft. to the tarp. It will be crazy heavy and almost impossible to transfer to your raised bed. So I'm about to drop some knowledge on you, from here on out just measure each component with one of those 5 gallon buckets. Makes life so much easier and your back will thank me later!

Add one bucket full of each component at a time to your tarp. Peat moss is usually sold compacted, break it up before adding it to your bucket. Mix to combine. The best way to mix is to have a partner. Each grab an end of the tarp and gently mix by walking towards each other so the mix starts to fold on itself. You will do this several times.

I found it helpful to mist the mixture with water to help weigh down the peat moss a bit. Pour mixture into bed, wetting it down as you pour. You will be making several trips to your raised bed so do all your mixing next to your bed. Once you have fill the bed up with the soil mix, plant and water.

Cost
You may have to utilize a couple of your local nurseries and big box stores to find all your components to make your soil.

Vermiculite | $41.94 each
Peat moss | $11.97
Compost Mix | $23.94
Total cost | $77.85

I still have a wheelbarrow full of mix that I can use next planting season. This is a one-time expense so don't let this price tag scare you. The good thing is after your bed is filled, the only thing you will ever need to add is a trowel full of compost each time you plant a square.

I hope you found this how to post on how to make your own soil helpful. See ya soon!

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