Square Foot Gardening Soil
How to Create Mel’s Mix
You may be asking “whose mix”? Mel Bartholemew is the author of All New Square Foot Gardening and the founder of the square foot gardening method. He recommends filling your garden boxes with a special mix, instead of dirt. Here’s the mix, how much it cost, and the benefits:
- 1/3 vermiculite
- 1/3 peat moss
- 1/3 compost (from as many sources as possible)
This is done by volume. My garden beds were each 4’x4′ and needed 6″ of mix to fill them. 4x4x.5=8 cubic feet of Mel’s mix. I did three boxes, so I needed 24 cubic feet of mix, 8 cubic feet of each item. Now, this amount did fill my boxes initially, but as I watered and the mix settled, I added more compost.
I was able to buy the peat moss and compost at WalMart or Home Depot, but I only found the vermiculite at IFA Country Stores (Intermountain Farmers Association).
- 2 large bags (3.5 cu ft) vermiculite, $18.00 each
- 1 large bale (3.8 cu ft compressed, expands to be more) peat moss, $9.00
- 8 bags (1 cu ft) compost, $2.00 each (average price)
- 6 extra bags (1 cu ft) compost, $2.00 each (average price)
- TOTAL COST (three 4’x4′ boxes): $73.00
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. I was surprised when I pulled up my lettuce plants, the root ball was so large, nearly the whole square came up with it. I just shook out the mix and composted the old plants.
- 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. Again, I spent less than 1% of my time in the garden weeding. As a side note, I made the mistake of buying Nutrimulch (turkey droppings), and had tons of bugs. I won’t do that again!
- Drainage–with Mel’s mix, you cannot overwater! Mel recommends hand watering, but if you choose to irrigate, how do you get the right amount of water to each plant? Easy! I used a drip system, and watered away! Mel’s mix drains so well, you don’t have to worry about it.
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.
Mel’s mix can be more expensive, but there are several ways to cut costs.
- BULK COMPOST–First, I bought compost in bags, but you can go to your local recycling center and get a truckload for about $30.00. Depending on how many garden beds you have, this could really save you. Here are some compost sources in Utah.
- PLAIN COMPOST–Also, you can fill your boxes with straight compost. The only drawback to this is drainage–your plants can really get waterlogged if you don’t pay attention.
- MY MIX (MODIFIED MEL’S MIX)–1/4 peat moss, 1/4 vermiculite, and 1/2 compost mixed in the box.
In fact, this year I am doubling my boxes (building 3 more) and doubling my boxes (making them twice as high). For my existing garden beds, I will just add more compost. For the new beds, I will use my alternate version of Mel’s mix.
Mixing It Up–Tarp Method
Mel recommends mixing this on a tarp–so that’s the method I tried at first. The biggest mistake was that I tried to mix 24 cu ft of material at once. It was so heavy I could not lift even a corner. I know others who have mixed it in a wheelbarrow, but I think this is too small a batch. It might work to combine 8 cu ft at a time.
- 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.
The second year, I “upgraded” by boxes from 6″ to 12″. This required more soil: 4x4x1=16 cubic feet. To keep costs down (especially for vermiculite) I created My Mix:
- 1/4 vermiculite
- 1/4 peat moss
- 1/2 compost
Here are the updated calculations: 16 cubic feet per 4×4 box
- 4 cubic feet of vermiculite $25
- 4 cubic feet of peat moss $11
- 8 cubic feet of compost $25-40
The other change I made is in the method of mixing. I didn’t like using the tarp method because I garden by myself, and it was cumbersome and heavy. Instead, I put some of each ingredient into the box, mix with a spading fork, and then add more. When it’s dry it mixes easily, you can almost “stir” it. After your’e done, soak it really good with your hose.
Go here for information on what to add to Mel’s Mix after the first year.