chasv77answered grow question 4 years ago Hello, not sure about nutrient lockout during seedling stage, but those kinds of soils are too strong for seedlings.
I, as a practice, do not fertilize seedlings, as a good seedling soil such as Espoma or Light Warrior provides all nutrients during the initial 2 weeks or so, before I transplant to my super soil. And even then, I do not feed until after 30 days, of veg growing.
IMO, external feeding anytime before that 30 day period, just increases the chance of over feeding, before their time.
Good growing!!