Unless you have old seeds... Or bad genetics. Go directly to soil with no fuss. Maybe a light magnesium (kelp) pre-wash.
But "good" soil is not necessarily new soil. In fact low nutrient soil will encourage deep and wide root growth. I like using well used soil for my seedlings, or plant them directly around a mature plant in flower and wait until four true leaves are present...
Scooping out the seedling with some of the other plants roots and medium is then planted in a new rooting pot with low nutrient soil. I grow these to teens, about 8 inches, which leaves me with a well rooted sturdy plant ready for final large growing pot and rich pH balanced soil.
But you were also possibly "burning by window sill" or at least stressing them a bit.