Personnally I am still stuck with organic garden soil I buy in a farming cooperative + N and P organic inputs (which helps with vegetation, so to say without K elements which promote flowering that I don’t want until my plants are in the soil, otherwise they exhaust themselves early in the season…), and so using 4x4cm soil blockers, then transplant into 8x8cm plastic things, eventually in the soil. This for all solanaceae, and big transplants like that (ball head cabbages and so on).
That costs some money (lot of money…) + takes a lot of time., early in the seaon. My transplants are now nearly perfect, but every year I have problems with mice or snails on my hotbeds… who storm the greenhouse in a ay or another… For example this year, I thought I would lose one third of my eggplants and peppers after mice took these to create a nest… When I saw it I went into rescue mode for about 150 plants… without roots! Eventually it worked: all are fine now -i.e.e with roots!- but it has been awful seeing that… Worse: I lost 90% of nearly à 1000 tomato transplants, using many material sent from everywhere, with a huge work preparing it, with plans as you can imagine (about 150 references…): finished sowing at 2am in the morning, put them on my hotbeds, covered them nicely, went on a tour with a friend… came back 3 or 4 days later, nearly 100% had sprouted but 90% of them had been eaten by mice… So I have resown what I could in soil blockers since 2 times using what was left + buying new stuff to replace… in the process, I lost some material from breeders… feeling awful. That was a bit more than 1 month ago.
Anyway, it is not to ramble: it is why I want to convert most or all of these to direct seeding. So I don’t think I will spend too much effort trying to convert this system into home made starting medium, so to say I will spend much efforts into converting plants into direct seeding, notably 95-99% of cucurbits this year on a 600 square meter patch, but also selective trials of some solanaceae with @JesseI’s seeds + mine.
On the other side I will follow this topic because I believe I will always (??) have to sow early a few things like luffas, probably some peppers… A friend of mine made some trials with home made compost from a wood pile last year. I will ask him for infos.
PS: starting in soil blockers using these inputs sounds 100% contradictory with our trajectory of local adaptation, everything endophytes related: so you create artificial nutrition, then transplant into a normal soil with no inputs. So to say you don’t rely on endophytic mediation first, and then 100%. It is contradictory. At first stages of breeding, and as long as the main thing you want is CROSSES, to get back vigor, why not then, but later you should go towards direct seeding, Or should I say “I”? That is what I am intending to do with mosts, as my diverse populations are from 1 to 3 years old, time to go so soil without any prior artificial nutrition…