DIY potting/ starting soil

I’m considering starting a bunch of plants before transplanting outside. But I like to be local and sustainable. So to want to make a habit out of transplanting, I would need a DIY mix to start my plants in that can be made from stuff I have. Possibilities:

compost made from manure from goats, pigs, cows, horses, or poultry.

Rotten hay

Sand

Leaf compost from oak, maple, cherry trees

Am I like to be able to make a decent potting mix out of this stuff? Pasteurizing it would not be a problem.

It's great to start seeds as transplants. It lets you keep track of iffy seeds, old seeds, keeps birds away if they are covered, no snails or cut worms, etc.

I like to make a mix with 50% of my soil so their roots recognize it when they get transplanted, and 50% really finished compost that's been sifted.    Nothing moldy or goopy looking, no chunks of anything.  

The best soil is gopher mound dirt that has recently been pushed up.  I collect it in big buckets and store them in the shade with mulch over the top.  It's full of all the great stuff you want in soil that's been lurking underneath.

I start them in toilet paper tubes, filling the bottom half with composted manure and then the top half with the soil/compost mix.  The tubes go into a container that can hold water, usually a half gallon milk carton with one long side cut out.  That will hold 9 tubes, and the water that runs through them will get sucked back up into the soil and paper, keeping the tubes wet constantly.  Or a plastic shoe box, something like that.

By the time the transplant is 3" or 4" (finger length) the roots are usually starting to get through the tube.  I plant the whole tube in the soil with the top edge a little under the soil so it won't dry out.   Then mulch with the rotted hay, crushed leaves out away from the stem a little so the critters can't hide and gnaw on the stem.  Usually transplants that big are left alone.

I do something very similar. My soil, I mean dirt, is very clayey so my proportions vary.
I use one third of dirt, one third of compost and one third of mulch. This works well for seeding.

Then I should be using forestal seeding trays so the roots are at least 15 cm long before planting (my watering needs are that bad), but for the moment I'm making it with plastic milk bottles. These have a watering reservoir so I waste less water.

Thank you, this is so helpful! I’m growing amaranth this year for the first time and I hear it takes about a month to get going, during which time it has to be weeded and messed with. With little kids, I don’t want to set myself up for endless hoeing. But… I’m pretty sure I can talk my tots into filling seedling trays with potting soil

I like to use a recipe that's approximately:

- 1/3 fine-textured moisture retentive filler, without nutrition.  You can use your leaf mold for this. Also coconut coir.  Peat is the traditional ingredient used for this purpose in seed-starting mixes, but is SUPER unsustainable.  I avoid peat completely.

- 1/3 something with nutrition and microbes like compost.  Because my native soil is so heavy, and also has lots of unwanted seeds in it, I just use a small amount -- enough to inoculate the mix with native microbes, but not so much as to affect the texture.  If your "nutrition" element is concentrated, like manure or worm castings, reduce the amount relative to the low-nutrient filler.  Homemade compost has both nutrition and fibrous filler.  I like to sieve my homemade compost so I only have the fine-textured good stuff.

- 1/3 drainage, like sand, pumice, perlite, etc. to make sure the mix doesn't get water-logged.

Seeds carry their own nutrition for the first couple pairs of leaves.  Giving them lots of fertilizers is unnecessary, at least at first.  

They DO absolutely need moisture (but not too much!) and air (but not too much!) and fine textures so that the baby plants and new roots can easily find their way.