Mel's Mix Dirt for the Square Foot Garden

Dirt! Yes, today's post is all about dirt.... The dirt I use in my square foot bed is very specific. In the book “All New Square Foot Gardening” by Mel Bartholomew, they call it Mel's Mix and it is:

• 1/3 vermiculite
• 1/3 peat moss
• 1/3 compost (Mel recommends five different manufactures)

This is done by volume. My three small garden beds were each 4′x4′ and needed 6″ of mix to fill them. 4x4x.5=8 cubic feet of Mel’s mix. So I needed 24 cubic feet of mix, 8 cubic feet of each item. I ended up mixing one bag of vermiculite (3.5 cu ft), one bag of peat moss (3cu ft ) and one bag of each types of compost (so five bags 1 cu ft each) and that seemed to be about all the tarp (and our arms) could handle at a time. That mix filled just over one bed. 

The Benefits

Why not just use dirt? You can, but there are some great benefits to Mel’s mix:

• Planting and germination–Mel’s mix is much lighter than dirt, and it doesn’t get compacted down because you never walk on it. This allows seeds to push through much easier, so you don’t have to be so particular about what depth you plant the seeds.
• Root systems–It’s really easy for roots to grow and spread in Mel’s mix.
• Weeds–by this I mean, WHAT WEEDS! As long as you are careful with what compost you get, there are no weed seeds in your mix (unlike dirt). If a seed blows in, the mix is so loose it’s easy to tug them right out. One of my compost bags was mushroom based so I did have to pull out some shrooms...
• Drainage–with Mel’s mix, you cannot over water it drains right out! 

When you use Mel’s mix, you don’t have to worry about what kind of soil you have, or amending the soil. Every time you plant a square, you add a trowel of compost. You don’t have to rotate where crops are planted, or do anything special, unless you want to.

Cost break down

• large bag (3.5 cu ft) vermiculite, $23.00 each
• large bale (3.8 cu ft compressed, expands to be more) peat moss, $5.00
• bags (1 cu ft) compost, $2.00 each (average price)

Pour compost on a large tarp. If you used several types, mix it following the instructions below before adding other materials.

• Add vermiculite.
• Add peat moss.
• If it’s really dry and dusty, mist it down but do not get it wet (makes it heavier).
• Mix by taking two corners of the tarp and pulling them over the tarp (like making a burrito) until all the material is close to one edge, lay the tarp flat. Then take the opposite two corners and pull the other direction, lay the tarp flat. Switch back to the other side and pull until all material is running down the middle of the tarp.
• Now shift 90 degrees (so you are looking down the column of material) and repeat. Basically, pull north, then south, then north until it’s in the middle. Then pull east, then west, then east until it’s in the middle again. Repeat until it is uniformly mixed.

These are some of the bags that we used.

Laying everything out to see what we have

My hubby dumping out vermiculite

Our filled boxes!

We got the peat moss at Home Depot, the vermiculite at a local green house, and then the five types of compost were a challenge. We got two types at Home Depot, then three types at a different local landscaping and green house. We had to go to a few places to find enough different types of compost. Filling the boxes did take longer then we thought it would but now that I'm growing in the dirt the time was well worth it. 

Here are some other tips to help you. 

• Buy some extra bags of the cheapest compost to fill in if you need more stuff to fill up the beds. 
• A bigger tarp is better. A big tarp is easier to mix on and you can store your extra dirt in it. 
• Buy the bigger bags - you can get it cheaper that way
• If you can not find vermiculite you can use perlite.
• If you can only find three or four kinds of compost, go with it, I wont judge you and we just wont tell Mel...