Try not to make it hard to mix a batch of soil.
Mix it this way if your 2nd guessing - get a one gallon container like an ice cream container empy or something and a tablespoon.
I mix in this order and repeat as needed so I don't mess up: 1 gal. OF / 1/2 gal. Perlite / 2 tbsps. domalite lime per gal.,1 gal. OF, 2 tbsp. domalite lime per gal., mix like no tomorrow...repeat if more soil needed. As Long as you mixed up the domolite good should no be a problem.
Did you germ the seeds in a moist paper towl till white tails showed then plant tail down in moist watered soil using a toothpick to make a 1 inch hole? That is really about 100% unless you noticed some off colored roots like maybe yellow or very thick roots have not come up in the past. That would be a genetic thing causing an issue imo. It is nature and giving birth isn't 100% or we wouldn't have adoptions....
My background had some horticulture in it in the past. I enjoy growing roses, perennials, veggis, and herbs. I don't like annuals much b/c I don't like replanting. Depending on your area you may be late on planting veggis unless your talking fall veggis? Herbs are always good and easy in a container. Some fresh basil in a spegetti sauce mmmmgood. I went on a mojito kick last year and started making my own special spearmint for my own recipe of mojitos. Love em...mmmgood on a hot day. I am in the deep south where the margarita is king. Going for a couple tonight...
I would suggest including the preventive spray in your weekly plant tools. The neem oil is really the stuff that helps naturally prevents bugs. Doesn't kill them but doesn't let them reproduce and they don't like hanging out in soil with it. You May be ok without it. I am an organic guy if at all possible.