proportions for making mel’s mix from SFG website
24 cubic foot BATCH – Good for THREE 4’x 4′ boxes (each box holds 8 cubic feet):
Here is what we would suggest you buy as a start:
Two 4-cubic foot bags of coarse vermiculite.
One 3.9 cubic foot bale of peat moss (this bale is compressed and will expand to nearly 8 cubic feet when opened).
4-5 bags of a variety of compost to equal 8 cubic feet.
That will be approximately 1/3 each of each of the ingredients and will give you a total of almost 24 cubic feet of Mel’s Mix. Since a 4’x4′ 6-inch deep box requires 8 cubic feet, that batch is enough for 3 boxes.
It is best to mix in a large, open, indoor space that is well-ventilated, or even better outdoors on a non-windy day. We have found it best to mix the ingredients by emptying them onto a large tarp or piece of heavy plastic. Because the materials are dusty at the start, you should wear a standard dust mask. Keep the kids away from the mixing operation until you put the material into your boxes and wet it down. Thereafter, there should be no problem with dust even if all the material dries out.
Going back to the mixing operation, open and mix the various bags of compost together. Then add the compressed peat moss and break up any lumps. (This is easiest to do by hand.) Add the vermiculite and you can then carefully mix the 3 ingredients with a rake or hoe being careful not to cut the plastic or tarp underneath. Or, an even easier way to mix, is to have 2 people – 1 on each corner of the tarp – pulling the ends of the tarp towards the pile. The ingredients will turn and roll as you do so. Then move to the other two sides and pull the tarp the other way. You keep working your way around the pile and if the tarp is big enough to start with, the pile should mix very quickly.
12 cubic foot BATCH:
If you just want to mix up half a batch to start with, you would add together just one 4 cubic foot bag of vermiculite, 1/2 of the 3.9 cubic foot bale of peat moss and enough of the compost mixture to equal 4 cubic feet. Make sure you have mixed all the bags of compost together so that you will have a well-blended compost.
NOTE: If the compost comes in bags that are measured in weight rather than cubic feet, just add in equal parts of the 3 ingredients. (For example, one shovel of vermiculite, one shovel of peat moss and one shovel of the blended compost – use anything to measure – a box, a wheelbarrow, etc. Or, just eyeball the amounts. It doesn’t have to be exact.) One man recently wrote and pointed out that 12 five-gallon buckets equals 8 cubic feet. So, if you need to measure this is a good way to do it. Just use 4 five-gallon buckets full of each of the 3 ingredients and that will fill one 4×4 box.
If your compost is wet, you may need a little extra mixing to make sure the dry materials are evenly spaced about. Some people have wet down the dry materials before mixing in order to keep the dust down. However, that makes the mixture rather heavy and hard to maneuver. You can spray it lightly with a hose to keep down the dust.
Once it is all mixed, it can all be placed in your boxes. Make sure you have removed any weeds or grass that is growing under your box and then put down commercial weed barrier cloth, a layer of cardboard, or a thick layer of newspaper to keep weeds and grass from growing inside your box.
Any leftover material can be stored in plastic bags (reuse the bags the ingredients came in) for future use. It’s always good to have some well-blended compost stored since you will be using a trowel full of this each time you replant a square. This will replenish the nutrients needed for healthy plant growth.
IMPORTANT HINT: Make sure that the Mel’s Mix is completely moist all the way to the bottom of the box before planting. It holds more water than you can imagine so take a hose to it and add a lot of water. Dig down and make sure it is wet. It is also so important to use a well-blended compost made up of 4-5 different ingredients.