Wholly mackerel

i found the product, and your seedlings may need it if they are into stretch, i normally dont need nitrogen at all in my automatic grows, because the soil is rich enough, only if she very vigorous and gets lightgreen in the leaves she might need it from week 4 or 5 on, depends in the plant

if wholly mackarell is a Nitrogen fertiliser, i say its not necessary before they start to stretch, your seedlings sitting in 15l or more pots filled with soil and nutrients, thats enough for weeks NO nitrogen forweeks necessary